Spectrum of Robertsonian translocations in conseсutive newborns and in prenatal diagnoses for indications other than familial translocation (updated from ).
\r\n\tAs an analytical technique with realms of applications, EIS has seen major progress during the past few years. One reason could be the feasibility of implementing EIS in a system, and the other would be the usefulness of EIS data in determining properties such as reaction rate, as well as the diffusion coefficients. Applications of EIS varied between corrosion analysis and inhibition, food and drug analysis, monitoring the performance of batteries, and developing biosensors, etc. Impedance microbiology which is used to monitor bacterial growth in a sample, and tissue electrical impedance which is basically used for detecting abnormalities in morphology and health of tissues, are other examples for the applications of EIS.
Robertsonian translocations (ROBs) are common structural chromosome rearrangement in humans. Since they are central in the etiology of congenital malformations and reproductive disorders, it is natural to assume that they represent a thoroughly studied subject. However, on closer inspection, there are poorly studied areas within this field. Surprisingly, exact rates of ROB carriers were determined neither among consecutive newborns nor among patients with reproductive disorders. The literature reiterates the information on tenfold, or even more than tenfold, increase in the rate of ROB carriers among patients with reproductive disorders compared to the general population. In addition, the quoted rates among newborns vary depending on the source that the authors cite [1, 2, 3]. Another omission in the area under consideration is the lack of systematic comparative analysis of the ROB spectrum in various carrier groups. The phenomenon of exceptional rarity of some nonhomologous rearrangements was not given due attention. There are some enigmatic problems in the field not yet resolved. One of them, unusual segregation of maternally transmitted translocations, has been discussed for the last five decades [4, 5, 6]. Another, established more recently, is the unexpectedly low incidence of ROB-associated uniparental disomy among carriers of balanced rearrangement . The epidemiology of Robertsonian homologous translocations (HTs)/isochromosomes, due to their rarity, has largely not been investigated. The aim of this report is to present results of a comprehensive analysis of available data collected by researchers worldwide that allows a new look at the problems mentioned above.
Study groups: newborns, prenatal diagnoses for indications other than familial rearrangement (the main indication for prenatal testing was advanced maternal age, and the transmitting parent was defined following detection of a rearrangement in the fetus), spontaneous abortuses with regular and translocation trisomy for chromosome 13 and chromosome 14, carriers of rob (13;14)-associated maternal uniparental disomy for chromosome 14, couples with reproductive disorders, patients with male infertility, and ill-defined carriers of homologous translocation/isochromosome (listed in Additional files S1–S8: Tables S1–S10; Additional file 11: Supplemental References, available either on request or from
The rates, spectrum, and parental origin of major nonmosaic balanced rearrangements in the general population are presented in the Additional files, Tables S1–S4. Statistical analysis showed distributions of nonhomologous ROBs from all studied groups to be homogenous in all combinations; therefore, both control groups were aggregated for further analysis. In the aggregated control (Table 1), the results seem to be in accordance with current views on the spectrum of individual ROBs, with the overwhelming majority of rob(13;14) 71%, followed by rob(14;21) 12%; the remaining translocations are rare or exceptionally rare; rob(15;21) and rob(13;21) were detected once each (0.4%). The total frequency of all translocations, calculated for newborns, is 1.06‰ with 95% CI from 0.8 to 1.3‰.
|Studied group||Gender||Number of tested patients||Number of ROB carriers||Nonhomologous rearrangements||Homologous rearrangements|
|Newborns (Table S1)||♂♂||33,371||24 (25)a||18||0||0||0||2||1||1||0||1||1||0||0||0||0||0|
|Prenatal diagnoses (Table S3)||♂♂||56||35||4||0||1||0||12||3||0||1||0||0||0||0||0||0|
Data on patients with reproductive disorders are presented in Additional files S1–S3: Tables S1–S3. The distribution of translocations in couples with reproductive disorders (Table 2) is generally similar to that observed in the aggregated control group. However, the proportion of rob(13;14) is much less in couples with habitual abortion (139/245 = 57%, with 95% CI of 51–63%), while the proportion of homologous translocations is high (24/245 = 10%, with CI of 7–14%). The overall rate of ROB carriers among couples with infertility is 3.6‰ (95% CI of 2.8–4.1‰), and 4.8‰ (95% CI of 4.2–5.5‰) among couples with multiple miscarriages. These values, as can be seen, do not exceed ten times the value in general population. A high incidence of ROB was found among patients with male infertility, 7.1‰ (95% CI of 6.2–8.2‰). Among couples with miscarriages, there is a difference between males and females by proportions of carriers of rob(14;15) (1 and 6%, correspondingly) and carriers of rob(14;21) (5 and 14%, correspondingly). There is a difference between couples with habitual abortion and couples with infertility in involving of chromosome 22 into nonhomologous rearrangements (32/245 = 14% with 95% CI of 9–18% vs. 4/110 = 4.2% with 95% CI of 1.5–9%), as well as with patients with male infertility (2/201 = 1.3% with CI 0.3–3.5%). In addition, among HT patients with habitual miscarriages, most are carriers of translocations/isochromosomes 22 (7 of 24).
|Patients||Number of tested patients||Number of detected carriers||Nonhomologous rearrangements||Homologous rearrangements|
|Couples with infertility (Table S5)||♂♂||15,432||91||68||5||0||0||5||11||1||0||0||1||0||0||0||0||0|
|Couples with habitual abortion (Table S6)||♂♂||25,577||86 (87)a||56||3||0||2c||1||4||4||1||5||1||2||1||2||1||3|
|Patients with male infertility (Table S7)||♂♂||28,112||201||140f||11||1||0||9||27||1||5||0||1||2g||2||1||0||1|
Of note is the extremely low frequency of rob(13;21); no carriers of this translocation were found in the newborn population, while among patients with habitual miscarriage, with a fourfold concentration of translocation carriers, only one carrier of rob(13;21) was found. This suggests one possible mechanism, a negative selection against certain types of translocations.
This hypothesis is consistent with the data of British authors  who reported the discovery of three constitutional rob(15;21) carriers among 95 children with acute lymphoblastic leukemia. It was proposed that the mechanism of triggering the neoplastic process is chromotrypsis. The authors concluded that in carriers of this rearrangement, the risk of the disease is 2700 times higher than in the general population. Interestingly, their assumption of a population frequency of rob(15;21) of about 1 per 100,000 newborns is very close to the real value presented in this paper.
Indeed, rob(15;21) appeared to be a very rare rearrangement, which is clearly not supported by natural selection: in the normal population, only one carrier of a rob(15;21) was detected (sex not specified), while among about a twofold smaller group of patients with habitual miscarriage, eight carriers of this translocation were diagnosed. Five carriers of rob(15;21) were identified among patients with male factor of infertility. These observations are of significance for medical genetic counseling of the carriers. Firstly, it is necessary to find out whether the risk of leukemia varies among the carriers depending on whether this translocation is inherited or occurred de novo. Currently, such data are not available.
Based on this data review, it is evident that it is necessary to continue accumulating survey data of couples with reproductive disorders to establish the existence or absence of differences in the range of ROB both between the patient groups and the population.
The sex ratios (SR) and parental origin of major nonmosaic balanced rearrangements in the general population are presented in the Additional files, Tables S2 and S4. The observed sex ratio was 1.06 (95% CI 1.04–1.07) which correlates with population ratios worldwide (Table S2).
The majority of both RECs and ROBs detected among conseсutive newborns (but not inversions) occurred de novo. Interestingly, the proportions of mutant REC and mutant ROB in newborns were similar (9/50 = 18% and 7/52 = 13%, correspondingly), despite different parental origins: RECs arise predominantly in spermatogenesis [10, 11], while ROBs arise predominantly in oogenesis [12, 13].
Some female prevalence among transmitting parents was in concordance with reported data on REC carriers (23mat/18pat), but not on carriers of ROB (24mat/21pat), since according to common conception, a twofold female predominance should be expected in this group due to reduced male fertility of ROB heterozygotes .
However, the most intriguing finding is the SR variability in newborns depending on the type of rearrangement (Table 3); there were equal numbers of REC carriers of both sexes (31 M/31F; for rates of 0.93 and 0.98‰, correspondingly) and a notable female predominance among carriers of ROB (27 M/41F, for rates of 0.77 and 1.24‰, correspondingly). The difference between the SR among carriers of ROB (0.61 with 95% CI of 0.27–1.00) and the SR among tested newborns (1.06 with CI of 1.04-1.07) was statistically significant (Bayes approach).
|Studied group||Reciprocal translocations||Robertsonian translocations||Inversions|
|Maternal origin||Paternal origin||Maternal origin||Paternal origin||Maternal origin||Paternal origin|
|Newborns (Table S4)||15||8||8||9||11||13||7||14||2||6||0||3|
|23 M/17F, SR = 1.35||18 M/27F, SR = 0.67||2 M/9F|
|Prenatal diagnoses (Table S5)||51||43||52||36||26||43||23||35||45||49||54||47|
|103 M/79F, SR = 1.3||49 M/78F, SR = 0.63||99 M/96F, SR = 0.96|
|Total||126 M/96F, SR = 1.31||67 M/104F, SR = 0.64a||101 M/105F, SR = 0.96|
|Sex ratio with 95% CI||0.92 1.221.62||0.500.680.93b||0.771.031.39|
Analysis of the SR according to the parental origin of rearrangements showed female preponderance among ROB carriers in either maternal or paternal origin or de novo origin: 11 M/13F, 7 M/14F, and 2 M/5F, correspondingly. Among carriers identified prenatally for indications other than familial rearrangement, female-based SR was found for both maternally and paternally transmitted rearrangements: 26 M/43F and 23 M/35F, correspondingly.
Collectively, among carriers of ROB with known parental origin, there were 67 males and 105 females (SR = 0.64), a difference from the expected ratio of 1:1 was determined to be significant statistically by both traditional statistics (p = 0.0033, binomial test) and by a Bayes approach (Table 3). Among offspring of REC carriers and carriers of inversion, SR was not different statistically from the expected ratio of 1:1. (126 M/96F, SR = 1.31 and 102 M/105F, SR = 0.96, correspondingly).
Among ROBs identified in newborns, the vast majority of the cases constitute translocations between chromosomes 13 and 14 (50 of 61). It is these rearrangements that determine unusual SR among ROB carriers: out of 50 carriers of der(13;14), 18 were males and 32 were females (SR = 0.56). A similar ratio was observed among fetuses with der(13;14): 32 male carriers and 53 female carriers (SR = 0.60). In total, SR among carriers of der(13;14) was 0.59 (50 M/85F), which is statistically significant from the expected 1:1 ratio both when using standard statistics (р = 0.001) and when using Bayes approach.
Thus, there is currently unexplained mechanism for maintaining female-biased sex ratio in carriers of ROB. A biased SR among offspring of male ROB carriers would have been explained by some meiotic process providing preferable production of X-bearing gametes with ROB. However, for female carriers, such a mechanism cannot be considered, since women produce X-bearing gametes only, and the offspring’s gender is determined by male gametes. For an explanation of the discussed phenomenon, the author suggests application of the concept of sex-specific correction of initial trisomy mostly in female embryos [15, 16]. In relation to ROBs, that means the loss of the odd chromosome is not involved to the translocation. If it is true, among carriers of balanced rearrangements, female-biased SR is expected, along with male preponderance among carriers of unbalanced translocations.
Carriers of an unbalanced 46,+13,der(13;14) rearrangement are rarely found among liveborns. In the population of 64,905 newborns, translocation T13 was detected in four instances; among them only 1 was identified as der(13;14). Similarly, they are rarely found at amniocentesis in the second trimester: 2 instances only among 52,965 and 31,194 tested fetuses [17, 18]. Carriers of the other unbalanced derivative of rob(13;14), i.e., translocation trisomy for chromosome 14, 46,+14,der(13;14), are unlikely to survive to a long gestation age. Therefore, aiming to obtain data on SR among carriers of T13 and/or T14, the author analyzed studies on chromosomal constitution in spontaneous abortions.
Table 4 summarizes the data from 26 surveys that detected cases of regular and/or translocation trisomy (T) of either chromosome 13 or 14 (see Additional file: Table S8). Analysis showed that among abortuses with regular T13, there were some predominance of male carriers, 75 M/63F (SR = 1.2), not statistically different from the population ratio of 1.06. In contrast, an unusual increase in the proportion of male carriers was observed among carriers of translocation T13 (17 M/3F) which might be interpreted as evidence supporting female-specific correction of translocation trisomy. Increased SR among carriers of translocation T14 in comparison with carriers of regular T14 was observed as well, with 15 M/9F (SR = 1.7) vs. 25 M/39F (SR = 0.6), correspondingly. It is quite possible that elimination of male embryos trisomic for chromosome 14 occurred at earlier stages of embryo development.
To evaluate whether a correction of translocation T14 occurs predominantly in female carriers, one may study the SR among individuals with uniparental disomy 14, upd(14). Unlike upd(13), upd(14) carriers demonstrate clinical manifestations depending on the sex of the transmitting parent and have therefore undergone cytogenetic and molecular testing. Analysis of published cases with reported sex of the carriers of upd(14) showed that of 16 patients with 45,der(13;14),upd(14), 12 were females, including 8 carriers of upd(14)mat [20, 21, 22, 23, 24, 25, 26, 27] and 4 carriers of upd(14)pat [28, 29, 30, 31]; the remaining 4 male patients had upd(14)mat [32, 33, 34, 35].
It was logical to assume that in this group, incomplete correction of initial translocation trisomy 14 may take place as the result of postzygotic events, i.e., mosaicism can be found. Moreover, carriers of mosaicism were expected to be females. Accordingly, mosaicism 45,XX,der(13;14)/46,XX,der(13;14),+14 was detected in two female patients [20, 21].
Among carriers of other translocations with upd(14)mat, there was also a female predominance, with four females out of five patients [25, 36, 37, 38, 39]. This observation supports the suggestion that the trisomy correction phenomenon might not be restricted to unbalanced translocation (13;14). The data obtained is of clinical significance, indicating that female ROB carriers are at a much higher risk of uniparental disomy than male ROB carriers.
The data obtained, while presenting evidence for sex-specific correction of trisomy as a reason for female predominance among carriers of balanced ROB, are in apparent contradiction with the data on low incidence of uniparental disomy carriers among both prenatally tested fetuses and abortuses with familial translocations. According to collective data, the incidence of translocation trisomy correction causing uniparental disomy does not exceed 1% . It is understandable that so rare an event cannot cause the observed bias in the sex ratio. In turn, the low incidence of uniparental disomy due to trisomy correction is in contradiction with the data on a very high incidence of self-correction found in preimplantation embryos [40, 41].
An assumption of a special correction mechanism leading to biparental disomy might explain this contradiction. Such a mechanism, a preferential loss of maternal chromosome (and, hence, reconstitution of biparental disomy) in female embryos, was suggested as an explanation of the twofold male predominance among patients with Prader-Willi syndrome due to maternal uniparental disomy  (for details, see Section 4.3.2).
Preferential loss of maternal extra chromosome in carriers of inherited unbalanced translocation may be explained “topographically”: in the human zygote, maternal and paternal pronuclei are separated, and this condition is preserved during some mitotic divisions. In the case of translocation trisomy (which mostly have maternal origin), a competition for spindle attachment occurs. The vast majority of human ROBs are dicentric . The dicentric structure allows for more spindle attachment sites and consequently for a “stronger” centromere , which provides preferential loss of maternal extra chromosome. At later postzygotic stages, while trisomy correction results in mosaicism for balanced translocation, preferable loss of maternal chromosome should not occur.
Sex-specific correction of transmitted translocation trisomy might explain either partly or entirely the phenomenon discussed since the 1960s, namely, transmission ratio distortion in offspring of female carriers of ROB [4, 5, 6]. Unfortunately, the precise mechanism of selective trisomy correction in female embryos is undefined.
When groups of couples with reproductive disorders are compared (Table 2), tenfold difference is evident between them by both an incidence of HT carriers (0.03‰ in couples with infertility and 0.4% in couples with habitual abortion) and a proportion among all detected ROBs: 0.9% (1/111) with 95% CI of 0.2–4.9% vs. 10% (24/245) with CI of 7–14%, the difference is significant at p < 0.0013. And since the only carrier of HT in the group with infertility was a woman, one can assume that her “infertility” was due to early undiagnosed pregnancy losses.
In patients with male factor of infertility, it was originally intended to combine them with males from couples with infertility, especially since these groups did not statistically significantly differ either in the frequency of the detected ROB carriers (0.36 and 0.21‰, respectively) or in the spectrum of translocations. However, it was taken into account that in the surveyed couples, about half of males were partners of females with a female factor, and therefore their aggregation into one group is unnecessary. Nevertheless, despite the fact that in this group, the majority of the patients had a proven male infertility factor, proportion of HT carriers was only 3% (6/201 = 3.3 with 95% CI of 1.4–6.4%), which is not statistically different from that in the males from couples with infertility (0/91 = 0.0% with CI of 0.0–4%) at p = 0.18. Of note is that one of the six patients presented mosaicism for balanced/unbalanced HT .
Seventy-one single cases of HT carriers, including 48 females, were identified from the literature (Additional file S7). Almost all female carriers, except for two, were tested cytogenetically for multiple miscarriage and/or abnormal offspring. Of 23 male carriers, only 2 were tested for infertility, 1 of whom had mosaicism for an unbalanced rearrangement.
Table 5 presents the data collation from single reports, systematic surveys of couples with reproductive disorders, and also the publication of the authors who summarized the results of the diagnostic laboratory without detailing the indications for the testing. The most frequent were the HT of chromosome 13 and chromosome 22. A somewhat smaller number of asymptomatic carriers of HT of chromosomes 14 and 15 might be explained by the presence of imprinted genes on these chromosomes, a proportion of both HT14 and HT15 carriers have clinical manifestations depending on which of the parents the HT is inherited from (see Section 3.4).
|Translocations||Couple with reproductive disorders (Tables S5, S6)||Single cases tested for various reasons (Table S9)||Consecutive patients from a genetic unit ||Total||Sex ratio|
The sex ratio in carriers of HT of chromosomes 13–15 and 21 is female biased, varying from 0.21 to 0.54, with the overall figure of 0.34 (22 M/64F) with 95% CI of 0.21–0.56. The predominance of female individuals among carriers of chromosome rearrangements of this type is explained by the sex-specific instability of pericentromeric regions [15, 69]. In contrast, sex ratio among carriers of HT22 is not female biased (15 males/13 females, with 95% CI of 0.56–2.45), which might indicate some different “circumstances” of the formation of HT22 and the other acrocentric chromosomes. It is known that HT may have either a meiotic or mitotic origin and may be mono- or dicentric and biparental or uniparental . All the information that the authors reported on the origin of HT is included in Additional file: Table S9. However, its scarcity does not allow drawing any conclusions as to the possible differences in the mechanisms of the formation of certain HT.
The data of the previous study suggested that homologous translocations do not contribute to a disturbance of spermatogenesis . The present study showed that in patients with a male factor of infertility, the percentage of HT is 3% of the identified ROBs, in contrast to 10.5% in partners of women with miscarriage (although in the latter group about half of the individuals are partners of women with a female factor for infertility). It was noted that of the 22 male HT carriers (Additional file: Table S9), only 2 have been evaluated for infertility, 1 of them having a cell line with an unbalanced HT . In the analysis of a testicular biopsy of another carrier, the authors found no reason to link the presence of HT with the impairment of his spermatogenesis .
Thus, in the overwhelming majority of cases, male HT carriers produce gametes capable of fertilization. The absence of spermatogenesis disorders, typical to nonhomologous ROB carriers, is most likely due to the ability of chromosome arms of HT to conjugate, as previously reported . The authors, examining a man whose wives had habitual miscarriages, found completely normal spermogram parameters and testicular histology, wherein conjugation between the long arms of the isochromosome 14 took place in such a way that the chromosome did not differ from the usual bivalent. It is obvious that such a configuration is fraught with the possibility for formation of a ring chromosome. Indeed, in the offspring of two carriers of HT, there were children with ring chromosomes, most likely formed from parental HT [48, 49]. There are multiple reports in the literature on patients with ring chromosomes accompanying homologous translocations but of postzygotic origin [50, 51, 52, 53]. Stetten et al.  suggested that the presence of HT is a necessary precursor to the formation of ring chromosomes.
Despite the fact that carriers of nonmosaic HT produce only abnormal gametes, there are cases of the birth of healthy children with the same rearrangement [54, 55, 56, 57, 58, 59]. These rare cases can be the result of one of two mechanisms: the syngamy of a gamete carrying HT with a gamete nullisomic for the same chromosome or correction of a trisomic zygote by losing a free extra chromosome. It is curious that out of seven of these cases, in four of them, HT22 was transmitted. Studies of the inheritance events of balanced HTs provided initial evidence that chromosomes 13, 21, and 22 did not bear imprinted gene.
Several cases of the birth of healthy children with normal chromosomes to apparently nonmosaic HT carriers were reported [60, 61, 62, 63, 64]. The birth of chromosomally normal children indicates the presence of a normal line in the gonads of the parents with HT. In addition, one can assume a rare event—sporadic dissociation of centromere. This phenomenon was shown both for ROB [65, 66] and for nonacrocentric chromosomes [67, 68]. Another possibility was discussed as well, gonadal mosaicism in unbalanced HT (translocation trisomy), since gamete precursor cells with such a set of chromosomes are expected to produce 50% of daughter cells with normal karyotype .
It would seem that the feasibility of this possibility with respect to male patients is highly doubtful, since the presence of an additional chromosome induces spermatogenesis disorders. For example, it is well known that women with nonmosaic trisomy of chromosome 21 (Down’s syndrome) are fertile, while men are mostly infertile, due to impaired spermatogenesis . It is possible to assume that it is the presence of a cell line with unbalanced HT in the gonads as a result of incomplete correction of the original translocation trisomy that causes spermatogenesis disorders in carriers of apparently balanced HT.
Currently, infertility due to chromosomal abnormalities, with the corresponding pathologies of spermatogenesis, is overcome by reproductive technologies, and, paradoxically, it is possible that it is in male HT carriers with infertility that there is a chance to have a healthy offspring. For example, encouraging results were obtained using reproductive technologies for the production of healthy children from male carriers of trisomy 21 [71, 72].
In general, the reproductive prognosis for carriers of HT is pessimistic. But, given the nonzero chance of having gonadal mosaicism in them, we can recommend testing, the algorithm of which was published [69, 73]. In addition, another possibility of having a healthy child with the same rearrangement was discussed, that is, gamete donation from a carrier of the same balanced rearrangement, which does not carry imprinted genes .
A scrupulous search in available literature yielded 10 ill-defined carriers of HT14 and 28 carriers of HT15 (Additional file: S10). Although the number of published cases of HT with clinical manifestation of uniparental disomy is small, there are some observations of interest.
Unlike asymptomatic individuals with biparental HT14, patients with UPD(HT14) demonstrate some male predominance (6 M/2F), while the majority of them (eight of ten) had maternally derived rearrangement. More cases are needed for solid conclusion on the SR in this group.
Strong female predominance among patients with maternal UPD(HT15) was first reported in the discussion of the concept of trisomy correction due to parent-sex-specific loss . In previous studies, a male predominance among patients with maternal non-ROB UPD (15) was suggested to be the result of either a bias of ascertainment due to milder phenotype in female UPD patients or difference in survival of early trisomy 15 conceptuses . However, in contrast, Kovaleva noted that among patients with UPD(HT15), there was no male predominance, with five male and ten female carriers . Mitchel et al. also suggested a possible difference in the probability of trisomic zygote rescue depending on the sex . However, the predominant rescue of trisomic male zygotes would result in a male predominance in mosaic cases, while no male predominance was reported in a collective sample of 50 fetuses with T15 mosaicism (SR = 0.67) . Kovaleva suggested that the male prevalence among patients with non-ROB UPD(15) can be explained by female-specific loss of a maternal chromosome, causing biparental inheritance and therefore complete correction of trisomy in females (without UPD) . For an explanation of the female predominance among carriers of UPD(HT15), parent-sex-specific loss should be considered, but in this case, a preferential loss of paternal extra chromosome from female trisomic zygotes with unbalanced HT is suggested.
Nine reported HT15 carriers with Angelman syndrome were males. All of eight tested for UPD patients had paternal isodisomy. Among homologous HT, the majority of them were established to be isochromosomes. Several mechanisms of isochromosomes formation were discussed, including gametic complementation, trisomy rescue, and monosomy rescue. It was suggested that they mainly should be formed postzygotically (see for review ). However, postzygotic formation of pericentromeric rearrangements is essentially female-specific [15, 69].
A strong male prevalence among patients with UPD(HT15) can be explained by meiotic event, nonhomologous co-orientation of the isochromosome with X chromosome during the first meiotic division in the spermatocyte. In such a case, X chromosome and isochromosome travel to the opposite poles, providing preferential segregation of isochromosome with Y chromosome. This mechanism, proven for Drosophila [75, 76], was proposed to explain male excess among carriers of paternally derived regular trisomy 21 , as well as male-biased SR in trisomic offspring fathered by carriers of dup(21) , and in trisomy 21 offspring inherited paternal noncontributing rearrangement .
It is interesting that very recently the epidemiology of Robertson translocations was suggested to this author as not worthy of any attention. Currently, in this field there are multiple unanswered questions. Further studies are required to elucidate the nature of female preponderance among carriers of Robertsonian translocation in newborns, as well as of other intriguing phenomena uncovered in this paper, such as a nonuniformity in the HT spectrum and difference in sex ratio between the carriers of the HT22 and the carriers of HT of the other acrocentric chromosomes. Moreover, chromosome 22 is rather mysterious in the context of the differences in the spectrum of nonhomologous translocations between groups of patients with reproductive disorders. There is no clear understanding of the role of HT in the etiology of male infertility and what factors determine the association of part of HT with impaired spermatogenesis. In addition, there are some aspects of ROB epidemiology not considered in this chapter, including interchromosomal effect and mosaicism.
The author is greatly indebted to Prof. Philip D. Cotter (University of California, San Francisco, USA) for the helpful comments and amending English in this paper and to Dr. Nikita N. Khromov-Borisov (Almazov National Medical Research Centre, St. Petersburg, Russia) for statistical analysis of the data.
The presence of volcanic centers clustered in a monogenetic field involves possible control from the feeding plumbing system architecture. The range of chemical composition (i.e. major elements abundances such as SiO2 contents, trace elements, etc.) from the effusive as explosive volcanic rocks also lead to various interrogations regarding origin of the magma that circulate in the lithosphere below monogenetic volcanic fields. Most of all, the presence of spatial magma heterogeneities is a major observation discussed and synthesized for volcanic fields in subduction zones [1, 2, 3]. Visualization tools are required to facilitate these observations and analyses for understanding the building of minor volcanic centers as defining the origin of the magma in monogenetic fields.\n
The Chichinautzin Volcanic Field (CVF) in the center of the Trans-Mexican Volcanic Belt (TMVB) represents the ideal study case to improve observations and simplify visualization of spatial heterogeneities among a volcanic field. The high sampling density of volcanic rock samples in CVF literally favor the area for such studies. Building a spatial visualization model becomes necessary regarding natural hazards because of CVF vicinity to the greater Mexico city, globally one of the most populated urban area.\n
A novel spatial model and geomatic tool are thus presented here to illustrate the geochemical dispersion from sampled volcanic rocks. This spatial model is simple and involves high precision for object localization on a map. Geochemical markers (geomarkers) related to classic igneous petrological analyst tools now are given quantitative symbols and projected on a digital elevation model (DEM) background. Point symbols and polygons that mark specific ranges of values from the geomarkers show clear spatial magma heterogeneities that can be interpreted and used in various disciplines of geosciences.\n
The Chichinautzin Volcanic Field (CVF) in the center of the Trans-Mexican Volcanic Belt (TMVB) is a key zone to understand recent monogenetic magmatism in a subduction zone. The volcanism of CVF and seismic activity underneath is rift-related and is also affected by the subduction of the Cocos plate under North American plate [4, 5, 6, 7, 8, 9]. The age of volcanism is relatively young; geochronological 14C data, paleomagnetic measurements and the 40Ar/39Ar method applied on volcanic rocks give ages that goes up to 1200 ka [10, 11, 12]. The youngest eruption is the Xitle scoria cone around 1665±35 years b.p., whose lavas destroyed and buried the pre-Hispanic settlement of Cuicuilco .\n
The question of where volcanism occur is particularly of interest for geologists since around the populated valley of the greater city of Mexico, the CVF includes more than 220 quaternary cinder cones and few shield volcanoes, with their associated lava flows and tephra sequences (Figure 1a, b). In addition, the region is still “geologically active”; the volcanic structures tend to be aligned on E-W normal faults  with stratovolcanoes (Popocatépetl-Iztaccihuatl and Toluca) occurring at the intersection of N-S and E-W faults [16, 18]. The source of magmatic and seismic activity is also of concern , beneath all CVF, the inferred depth of the slab interface is changing between 80 km and drastically to levels far deeper than 100 km [8, 20]. The crustal thickness beneath the CVF is ~40 to 50 km which is the greatest in the TMVB [8, 9].\n\n
Noteworthy in the field of geochemistry,  mentioned a spatial variation from the composition of volcanic rocks and schematic sections were proposed to show where are the different kind of magmas in CVF [15, 21]. Overall, there have been lots of work done in the CVF relating its heterogeneity, and with the rapid development of analytical techniques in geochemistry, a new data compilation was needed after .\n
The geochemistry of the volcanic products in the CVF is characterized by basaltic andesite to dacitic rocks with alkaline to calc-alkaline affinities [9, 23]. The majority are subalkaline, except for the most mafic samples (ex: Chichinautzin and Guespalapa) which are transitional and plot in the alkaline field . Mafic melt compositions (basalt, basaltic andesites) are found in olivine phenocrysts holding glass inclusions of ~49 to <54 wt.% SiO2 (i.e. see Xitle,  and Pelagatos, ).\n
Since the first proposed petrogenetic explanation from Gunn and Mooser works (1970s), the origin of magmas heterogeneities in the CVF is still debated. Two different types of mantle-derived primitive mafic magmas have been suggested for CVF based on Sr-Nd isotopes, trace elements and mineralogical features [15, 26]. The first type is an OIB-like mafic magma, and is characterized as anhydrous [6, 9, 15, 23, 27, 28, 29]. The second type is associated to a metasomatized mantle source, with incompatible elements of a depleted mantle source, but enriched in mobile elements that are possibly coming from the subducting slab [6, 9, 23, 29].\n
A database of whole rock composition was produced by the compilation of geochemical data from 583 samples of volcanic materials within the CVF (Appendices). A total of 32 references was used containing whole rock data (major and trace elements from (A) Scoria cones in the Chichinautzin Volcanic Field (sample of lava, bomb and scoria), (B) Iztaccihuatl, (C) Popocatepetl, (D) Nevado de Toluca. In the case of stratovolcanoes (B-C-D), only were considered juvenile samples of pyroclast, pumice or a dome fragment.\n
Pairs of geochemical elements from whole rock analysis and representing high density sampling area were chosen based on their petrogenetic significance. All referenced data from the geochemical dataset of CVF were given latitude and longitude coordinates (Appendices I, II), then a spatial attribute is automatically associated when the tables are uploaded in a Geographic Information System (GIS). This database was projected with ArcGIS software  to detect any spatial trend. The compiled data come from 32 published works between 1948 and 2011 (See Appendix II for a list of the references used). Also, for comparison, data from the neighbor polygenetic volcanoes are included: Popocatepetl, Iztaccihuatl and Nevado de Toluca.\n
The systematic approach described above was possible to propose with a recompilation and a methodical statistical investigation of geochemical tracers of petrogenetic and tectonic processes. The statistic distribution of a single ratio is called a geochemical marker (geomarker).\n
In this review, 2 geomarkers were chosen based on the significance they represent in rock classification and petrogenesis. Two datasets of each geomarker were then created from the central geodatabase and plotted in the GIS map:
The alkali geomarker (464 datas) which represents the alkalinity of the rocks and may be indicative of assimilation from continental crust during formation of the magmas. The ratio is obtained by dividing alkalis over silica which transform the conventional bivariant graphic into a univariable value for mapping [31, 32, 33]. The Sr/Y geomarker (228 datas) is used to evaluate the significance of the alkali geomarker. The alkalinity of the rocks has high probability to be associated to the systematic of crustal thickness when high values from Sr/Y point symbols match areas with strong alkalinity. The equilibrium of plagioclase fractionating on Sr and both amphibole + garnet phases on Y is recognized to correlate with the variation of crust thickness in arc magmas .
The Ba/Nb geomarker (320 data) is used to geochemically characterize the tectonic environment. Ba is more soluble and mobile in subduction fluids . Nb is considered immobile in subduction fluids, it is not added to the mantle asthenospheric wedge and the rising basaltic melts, because it remains in the metamorphic rocks of the subduction zone [35, 36]. High ratios of Ba/Nb are then suspected of magmas enriched in fluid coming from subduction.
The method proposed in this work uses spatial interpolation models which require evaluation depending on the data dispersion of the samples and previous geostatistics made on the databases. The principle of interpolation in cartography is applied to improve visualization of regional patterns of a natural phenomenon and to generalize a numerical distribution in a certain region [37, 38]. The equations of such models can be consulted in [37, 38], and also searched in the GIS tutorials [30, 39].\n
Evaluations on previous interpolation approaches to CVF were resumed in . Intercomparing of kriging, inverse distance weight (IDW) and Linear Decrease (LD) is necessary due to the difference of input parameters between each approach. Ordinary kriging is proposed here according to the high density of samples in several areas between Popocatepetl and Nevado de Toluca flanks, mostly between latitudes 19°00′ and 19°20′ (Figure 1). As petrologists are interested by geological factors that influence the geomarkers at different scales [27, 34, 35, 36], the semi-variogram evaluation preceding the ordinary kriging becomes necessary to determine at what distance are the geochemical changes tendencies . As a matter of fact, the common analyze of nugget, sill, and range for determining the spatial dependence of geochemistry is unique to this interpolation technique [37, 38]. If the preferential orientation of data positions in the map was constrained (i.e. anisotropy), the angle (in degrees) could be manipulated by specific kriging methods in several pieces of GIS software. In CVF, as seen in Figure 1, the large 2500 km2 area contains too many sources of anisotropy, which lead to eliminate angles dependence along the input parameters.\n
The interpolation model is only applied for the monogenetic cones of the CVF, because the material dispersion is not the same for the eruption of stratovolcanoes. A map with punctual representation of each calculated average composition at each volcanic emission center is compared with the original dataset (Figure 1) and used for the interpolation model. When the raster model is obtained for the alkalis and Ba/Nb geomarkers, four categories of raster values are associated to quartiles in four categories of colors used for the geomarkers of CVF and then transformed into polygon shapefiles. The mapped results of interpolation of CVF is sliced in the GIS with the same four quartile limits (the same colors) for each range of values.\n
As for other interpolation techniques, the limiting distance (Do) chosen for considering a maximum number of points is important [37, 38]. This is determined for modeling the distribution of rock geochemistry because it is setting a maximum distance of influence between different sampled sites. This limiting distance (Do), or technically called “search radius” use a weighting exponent adjusted to the influence of the distance between sample points. First, to provide estimated values at locations of interest and second, to generate values presenting the same dispersion characteristics as the original data .\n
To determine Do, the physical environment must be considered. In this study, a Do of 6000 m was used based on the maximum length of lava flows measured from 76 cones in CVF, this is considering that effusive rocks are emitted at larger distance than ballistic projectiles from explosive eruptions. A 6000 m buffer area was thus drawn covering almost all the data on the map and tried to avoid isolated samples (sometimes outliers). The buffer separates the farthest sample on the map from this artificial boundary. The radius is especially useful for limiting the interpolation calculation. In addition, by clipping for the same distance the resulting matrix image, a better design of the geomarker dispersion model is obtained. The drawing of the four polygons color categories is recommended to fit exactly with the four quantile categories that represent the range of pixel values.\n
The datasets of alkalis and Ba/Nb are analyzed with spatial geostatistical tools, specifically the Moran’s Index (I) because of its simple interpretation for determining the level of spatial autocorrelation (Table 1). The spatial autocorrelation from such index measures dependence among nearby values in a spatial distribution . It considers that variables may be correlated because they are affected by similar processes, or phenomena, that extend over a larger region [38, 41]. The index is the result of a specialized algorithm; it first takes into account the classes of distances created for point pairs that are more or less at the same distance to each other [30, 39].\n
|Moran’s I index\n||0.42\n||0.48\n|
For all point pairs within a distance group, the spatial autocorrelation index (I) is calculated and it can be summarized as follow [equation in ILWIS 3.7, 38]: strong positive autocorrelation (I > 0), strong negative autocorrelation (I < 0), or random distribution of values (I = 0).\n
Pattern characteristics of the data were also analyzed. The parameter Prob1Pnt was calculated using ILWIS 3.7. This calculates the probability that within a certain distance (column distance) of any point, at least one other point will be found, i.e. the probability to find the nearest neighbor of any point list within this distance. It is a direct measure of dispersion and for the case of CVF, it indicates if the sampling area is well covered for the 220 identified volcanic centers (Table 1).\n
To evaluate “how good” is the model, cross validation calculation was used where the goal is to have the smallest root-mean-squared prediction errors [30, 38]. The cross-validation method is based on percent error or PE (%) and a RMSE (root mean square error). It is the mean of the squared difference between the observed value (Pi*) and the predicted value (Pi), where n is the number of observations.\n
The geochemistry diagram shows alkaline enrichment in the four groups and greater dispersion for CVF (Figure 2A). The alkalinity is stronger for the stratovolcanoes and the rock names vary from basaltic trachy andesite to trachydacite. The CVF is classified between basaltic andesite to dacite. Iztaccihuatl have similar values from sample of East CVF or Valley of Puebla (same trend). The Nevado de Toluca has strong alkalis values (third and fourth quartiles).\n\n
As seen in Figure 2B, the total sample distribution is almost a Gaussian curve for all incorporated samples in the database. The Moran Index (Table 1) demonstrates data that are spatially clustered, but the distribution is not random. The study gives a probability pattern to find a first interpolation point for 8250 m.\n
From the semi-variogram evaluation on the model (Figure 2C), the determined range (first plateau) is given with the spherical function model at 13,000 m which indicates a smaller scale influence compare to the other ratios. It is interesting to see a maximum over ~20,050 m and for other distances (plateau at 39,500 m) which indicates different scale influence of the alkalinity.\n
High values (third and fourth quartiles) from the alkali geomarker as spatial dispersion are variable at large scale in general, from east to west in CVF (Figure 3). Large surface of high alkalinity and high Sr/Y ratios are found near the Sierra de Las Cruces (SDLC) and Nevado de Toluca, some others south of Valley of Puebla Scoria Cones and in the center of CVF. Regionalization of low values is found for large area in the center of CVF, but some low Sr/Y ratios do not match with high alkaline contents for Guespalapa, Chichinautzin, Herradura and Suchioc samples. The distribution of alkalinity follows elongated polygons over CVF (NE-SW and SE-NW tendencies), but small anomalies are also observed. Stratovolcanoes are represented by high values of Sr/Y among point symbols, but geostatistics show large ranges of alkalinity.\n\n
The geochemistry diagram, while in most cases there is no correlation with the large variation of Nb datas, Ba values generally are higher for CVF, but there are no positive-negative relationships with Nb (Figure 4A). CVF have widely scattered values, the Nb values of Popocatepetl and Iztaccihuatl are generally lowers, but Nevado de Toluca’s values are higher.\n\n
The total sample distribution appears as two Gaussian curves. Those curves represent two populations of data with distinct patterns and two central tendencies (Figure 4B). Since Ba is not variable inside each group, the distribution of the Ba/Nb ratio is controlled by Nb. From Moran Index, the data form clustered pattern without a random distribution. The study gives a probability pattern to find an interpolation point for 9500 m so the influence between each sample is less important than for alkalis. From the semi-variogram, the determined range is given at 14,500 m which indicates a larger scale influence compare to the other ratios. A maximum is present at ~38,000 m (Figure 4C).\n
On the map, there are important first order tendencies. The entire CVF is exceptionally low, but regionalized and high values are found around the stratovolcanoes where the Nb is the lowest (La Hoya, Loma Sacramento, Tenayo), but also through SDLC or near Nevado de Toluca. The geochemistry changes from east to west starting from the Popocatepetl area (Figure 5). The polygons from the Ba/Nb spatial model are clearly elongated in a N-S direction.\n\n
The analysis of pattern (Table 1) showed that samples were grouped in disordered cluster without random dispersion, reflecting the different field strategies that influence the targeted investigated area of CVF. This dispersion diverges from systematic grids performed for small scales mineral exploration tactics or soil surveys .\n
The measure of dispersion gives values between 8250 and 12,900 meters and it is inversely proportional to the quantity of samples in each dataset. Despite those distances, the spatial dependence of the models varies between 13,000 and 18,000 meters (Figure 2C,4C; see semi-variogram evaluation). The changes of geochemistry are interpreted to occur for small distances between eruptive centers, but also for ranges over larger distances as it is shown for alkali, Sr/Y and Ba/Nb datasets. Finally, from observation of the point value symbol maps (Appendix I), despite of the rich geological knowledge and sampling works in CVF, the measure of dispersion allows to interpret an insufficient density of certain sampling area, particularly for monogenetic cones N-E of Xitle in urban sector, in the valley around Sta. Cruz volcano, and south of the CVF (forest).\n
The evaluation of rock chemistry affinity can be used to evaluate target for petrological investigation and resume spatial patterns as a clear idea of geochemical distribution of a monogenetic field. On the other hand, the presented methodology finds limitations for different reasons (we proposed four factors):
Detailed toponymic descriptions are furnished without coordinates of samples by some authors which complicate assigning geographical coordinates (Appendix II; the number of references being n = 15/32). This is in addition to the quantity of elements analyzed for geochemistry in certain sectors (different analytical instrument, necessity or not to use rare earth and trace elements) as the targeted material from the publication which involve for some authors to study different kinds of external and internal petrological processes.
Control of arbitrary parameters such as the search radius and weighting exponent in the interpolation approach can be affecting the error and precision of the model . The IDW and LD techniques are ideal in areas without anisotropy and where the quantity of point neighbors is not critical (i.e. constant in a structured sample grid [30, 37, 38, 39].
Sampling density and dispersion as determined with (I) find limitations from the physical environment (topography, vent locations reported in literature, nonpreferential flow orientation, etc.).
Strategical sampling affects the distribution of sampling site positions (i.e. various objectives of petrological sampling, sample distance to road of access, uncertainties of rock sample association to emitting vent, etc.).
Trace element ratios Ba/Nb show first-order trends and one maximum in the semi-variograms for 38 km (Figures 2,4). Spatial variations of trace element ratios are correlated for limits that correspond to larger distances. These changes of geochemistry are visible in a larger area and may be related to large-scale tectonic effects which may be associated to new input material from the subduction zone .\n
Alkalis shown on the maps has tendency of second order (for 13,000 m) and have different changes of spatial dependence for larger distances interpreted in the semi-variogram (Figures 2,4). These second plateau and maximum can also be interpreted as secondary large-scale tendencies. At local scale, it perfectly marks the regional heterogeneity known in the CVF, but larger scale effects also occur (i.e. For example Pelagatos and the center of the monogenetic field is clearly less evolved and less alkaline; see [25, 42, 43]).\n
The geochemistry of monogenetic cones satellites/boundaries of Popocatepetl, Iztaccihuatl: like the neighbor stratovolcanoes have volcanic arc affinity (high Ba/Nb), influence of crustal thickness (high Sr/Y) and constitute predominantly felsic rocks. Despite of this, alkalinity anomalies are observed, in some cases, few minor eruptive centers constitute low Sr/Y ratios, but high alkalinity (ex. Nealtica, Tetela), or even the contrary, high Sr/Y ratios, but low alkalinity (Cerro Xoyaca, Loma Tepenasco, La Joya next to Iztaccihuatl; ). Overall, the heterogeneity of the CVF monogenetic bodies decreases as it approaches the Popocatepetl-Iztaccihuatl stratovolcanoes. This distribution suggests the possibility that the CVF and the stratovolcanoes share the same mantle source which is a petrological evidence in literature [14, 44]. The contrast of Ba/Nb values between the stratovolcanoes and the center of CVF can be explained by different degrees of sediment contribution from the mantle , crustal assimilation (i.e. on Sr and Y; ), but also fractional crystallization, all having effects on the content of Ba and Nb .\n
The most remarkable observation in the spatial model is the similarity with the geomarkers to the east CVF and the Popocatepetl-Iztaccihuatl complex. This could imply that since Quaternary, the magma source of many monogenetic conduits east of CVF and minor eruptive vents find similar magmatic source/a common root in the mantle in the vicinity of the polygenetic edifices (ex. La Hoya, ).\n
At the eastern limit of the mapped faults in , a similar N-S trending corridor is observed with high Ba/Nb anomalies. This includes the Pelagatos volcano mafic rocks despite the intermediate alkalinity and Sr/Y ratios (Figures 3,5). Such signatures are associated to enriched mantle in incompatible elements. No regional faults are reported, and neither are lacustrine sediment covers east of Pelagatos . A clear lineation of scoria cones is observed as shown by the point map overlays (Figure 1; Appendices). A E-W large scale change of crustal thickness can explain the variation, but Sr/Y do not show this N-S systematic association nor gradual changes along the direction of the Cocos plate subduction under the continent [8, 20].\n
A different dispersion pattern of the magma conduits could occur in this area due to complexity of cortical pathways for magma, but as the interpolation model and semi-variogram indicate (Figure 4C), individual plumbing systems of the monogenetic field must share a deep mantle source. Large-scale geochemical changes from all geomarkers do not correlate with the subducting slab geometry [8, 20, 34, 46], which point out that spatial heterogeneities of magma source rather increase where mantle interact with continental crust.\n
Monogenetic cones north and south of CVF are more mafic, less alkaline and many aligned scoria cones share the same rock composition (Figures 3,5). Overall, monogenetic cones are spatially associated to E-W normal faults reported in the works of [16, 18] and recent mapping advances resumed in [10, 11]. Even though, no clear geochemistry (ex. Sr/Y) vs structural orientations associations are observed (Figure 1) contrary to some volcanic fields (minor eruptive centers along the Liquiñe-Ofqui Fault Zone, Southern Andes; [47, 48]). The normal fault systems in CVF also affect the crust below stratovolcanoes in addition to NE faults. This could imply to redirect orientations for magmas pathways and plumbing system depths. Thus, the extend of magma differentiation is variable and therefore the geochemistry of satellite monogenetic cones is modified to the polygenic edifices (i.e. Huililco monogenetic cones versus Llaima stratovolcano in Chile; ).\n
As for Nevado de Toluca, only Sta. Cruz and Tenango have remarkably similar trace element ratios (Figures 4,5); Sr/Y as for Ba/Nb are associated to the high topography from SDLC. Overall, the western part of CVF constitutes spatial changes of geochemistry that vary over small areas. For example, near the flanks of the SDLC, rocks are more diverse in SiO2 contents, have higher alkalinity and local interpolations show high Ba/Nb ratios [subduction signature). Then, further west, the same high Ba/Nb tendency follows a N-S corridor (Texontepec to Tezontle).\n
Local anomalies are various west of CVF and Tenango lateral fault system. Many E-W structures  do not correlate with the orientation of elongated polygons of high alkalinity and neither do they follow regional tendencies of spatial Sr/Y distribution (Figure 3). A more complex structural system can explain this difference according to the maps published in [1, 10, 49], which may imply contrasting basement lithologies (i.e. see [11, 50, 51]), crustal thickness or lithospheric fractures distinct in depth origin, movement and geometry in comparison to the Popocatepetl-Iztaccihuatl complex.\n
The geostatistic and geographical mapping model of volcanic bulk rock chemistry in the Chichinautzion Volcanic Field (CVF) served as a methodological approach to improve the comprehension of the spatial distribution of the magma heterogeneities inside a typical monogenetic volcanic field. The major methodological outcomes and geological explanations for such geochemical variations are resumed as follows:
The method presented here showed incertitude particularly for interpreting alkalis and Sr/Y lineation on the final models (Figures 2,3). Limitations were encountered for assigning geographical coordinates, to control arbitrary parameters for spatial interpolation, to integrate physical environment parameters and to consider all strategical sampling objectives that may influence sample rock positions cumulated since 1948. The Moran Index (I) and the parameter Prob1Pnt helped to determine sample dispersion, which become mandatory to determine if some sectors inside a monogenetic field as CVF should be preferred for kriging, IDW or LD. It is consequently recommended to segment the area of study from monogenetic field and use the kriging method where a preferential sample orientation for high sample density cover is observed (satellite cones on the same flank from a polygenetic system, unidirectional topographic gradient, sampling along a lava flow or a structural lineation). Sectors where sample orientation is random and distribution is homogeneous should consider the Inverse Distance Weight (IDW) and Linear Decrease (LD).
The tectonic significance of high Ba/Nb geomarker is particularly of interest to indicate contribution of fluids derived from the subducted plate. This occurs in addition to the highly depleted mantle signature in the region of stratovolcanoes [21, 28, 29, 44]. One consideration is the presence of such anomalies related to amphibole fractioning  and even garnet from a deep source (~400 km; ). Another consideration is that such magmas are deeply sourced where hydrated fluids are produced by a metasomatized mantle source (from the slab, for example supported by [23, 29]). Despite of this association, such anomalies are geographically restricted to polygenetic systems. In addition, the Sr/Y ratio or alkalis geomarkers as Ba/Nb itself do not correlate with literature observations of the continental thickness [10, 11, 16, 18] nor the contact geometry of the subducted slab vs. lower continental crust [8, 20, 46]. Consequently, below CVF, rather than the slab influence , it is suggested that the role of lithospheric mantle–crust interaction is crucial to modify geochemical signature on the magmas feeding minor eruptive vents.
Shallow depth rigid continental crust (thickness and fractures) does not allow sufficient time and space for magmas to record subduction signature, therefore, the fast magma ascent feeding typical monogenetic systems do not easily record high Ba/Nb ratios . In some cases, those magma could rather come from a fertile mantle, some with OIB signature, some hybrid depleted mantles [7, 9, 15, 21]. If this inference is correct, obstacles in the continental crust could be slowing down the frequent injection of new batches of magma feeding new minor eruptive vents around Iztaccihuatl-Popocatepetl, and Nevado de Toluca volcanic complexes. The plumbing system architecture of those stratovolcanoes already channel volumetric magmas derivated from a contrasting mantle-crust source.
The persons especially thanked for the technical support are Isaac Abimelec Farraz Montes (technician), Osvaldo Franco Ramos (student at Instituto de geografia, UNAM), and Laura Luna (technical secretary at Instituto de Geologia, UNAM). Dolores Ferres and Marie-Noël Guilbaud from Instituto de Geofisica (UNAM) reviewed datasets and gave important opinions about the methodology and the volcanological aspects of the work.\n
This work was supported by the Fonds de Recherche du Québec Nature et technologies (FRQNT) (Concours B1, Comité B4 (Maîtrise) who helped to support the Master program between 2010 and 2013 at Instituto de Geología, Universidad Nacional Autónoma de México (UNAM). The submission work process is supported by Conicyt Fondecyt Fondo Nacional de Desarrollo Científico y Tecnológico, with Project Code 11190846 attributed to Dr. Philippe Robidoux from Centro de Excelencia en Geotermia de los Andes (CEGA) and Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile.\n
Building the Geodatabase\n\n
Table of reference for samples used in the Geographic Information System (GIS)\n
|1948\n||Arellano, A.R.V., 1948. La composicion de las rocas volcanicas en la parte sur de la Cuenca de Mejico, Boletin de la Sociedad Geologica Mexicana, Tomo XIII, p.81-82, Cuadro 18\n||Yes\n||No\n||Description\n|
|1975\n||Whitford, D. J., Bloomfield K., 1975. Geochemistry of late Cenozoic volcanic rocks from the Nevado de Toluca area, Mexico, Year Book Carnegie Inst. Washington 75 , p. 207-213, #4571 in GERMS database\n||Yes\n||Yes\n||Description\n|
|1975\n||Bloomfield, K. 1975, A late-Quaternary monogenetic volcano field in central Mexico, Aufsatze,Geologische Rundschau, 64: p.476-499\n||Yes\n||No\n||Maps\n|
|1985\n||Carrasco-Núñez, G., 1985. Estudio geológico del Volcán Popocatépetl, BS thesis, México DF, Facultad de Ingeniería, Universidad Nacional Autónoma de México, 134p.\n||Yes\n||No\n||Description\n|
|1987\n||Nixon, Graham T., 1987. Petrology of the Younger Andesites and Dacites of Iztaccihuatl Volcano, Mexico: I. Disequilibrium Phenocryst Assemblages as Indicators of Magma Chamber Process, Journal of Petrology, Vol. 29, Part 2, p. 213-368\n||Yes\n||No\n||Maps\n|
|1989\n||Pozzo, C. Ana Lillian Martin del Pozzo, 1989. Geoquimica y paleomagnetismo de la sierra Chichinautzin, Tesis que presenta la autor en cumplimiento parcial de los requisitos del grado Doctor en Ciencias (Geologia), Mexico -D.F., 148 p.\n||Yes\n||Yes\n||Maps\n|
|1989\n||Swinamer, Ralph Terrance, 1989. The Geomorphology, Petrography, Geochemistry and Petrogenesis of the Volcanic Rocks in the Sierra Del Chichinautzin, Mexico, tesis submitted to the Department of Geological Sciences, in conformity with the requirements for the degree of Master Science, p.212\n||Yes\n||Yes\n||Table\n|
|1995\n||Cervantes, P., 1995. Eventos volcanicos al sur de la Ciudad de Mexico, BS Thesis, México DF, Facultad de Ingeniería, Universidad Nacional Autónoma de México, 74p.\n||Yes\n||Yes\n||Description\n|
|1998\n||Arana Salinas, L., 1998. Geologia del volcan Pelado, BS thesis, México DF, Facultad de Ingeniería, Universidad Nacional Autónoma de México, 57 p.\n||Yes\n||Yes\n||Maps, description\n|
|1998\n||Delgado et al. 1998, Geology of Xitle Volcano in southern Mexico City - A 2000 Year-Old monogenetic volcano in an urban area, Revista Mexicana e Ciencias Geologicas, volumen 15, #2, 1998, p.115-131\n||Yes\n||No\n||Maps, description\n|
|1998\n||Romero Teran, Esther, 1998. Geologia del Volcan Ajusco, BS thesis, Facultad de Ingeneria, Universidad Nacional Autonoma de Mexico (Instituto de Geofisica), 50 p.\n||Yes\n||Yes\n||Maps\n|
|1999\n||Verma S. P., 1999. Geochemistry of evolved magmas and their relationship to subduction-unrelated mafic volcanism at the volcanic front of the Central Mexican Volcanic Belt, Journal of Volcanology and Geothermal Research, Volume 93 , p. 151-171, #3623 in GERMS database\n||Yes\n||Yes\n||Table, maps\n|
|1999\n||Arce S., Jose Luis, 1999. Reinterpretacion de la erupcion pliniana que dio origen a la Pomez Superior, Volcan Nevado de Toluca, Master thesis: Maestro en Sismologia y Fisica del interior de la Tierra, Postgrado en ciencias de la tierra, Universidad Autonoma Nacional de Mexico (Instituto de Geofisica), 92 p.\n||Yes\n||Yes\n||Maps, description\n|
|1999\n||Wallace, P., and I. Carmichael (1999), Quaternary volcanism near the valley of Mexico: Implications for the subduction zone magmatism and the effects of crustal thickness variations on primitive magma compositions, Contribution to Mineralogy and Petrology, vol. 135, p.291-314\n||Yes\n||Yes\n||Table, maps\n|
|2000\n||Verma, P. Surendra, 2000. Geochemistry of the subducting Cocos plate and the origin of subduction-unrelated mafic volcanism at the volcanic front of the central Mexican Volcanic Belt, Geological Society of America, Special Paper 534, p.195-222\n||Yes\n||Yes\n||Table, maps, description\n|
|2000\n||Gonzalez Huesca, Alberto, 2000. Estudios de detalle estratigrafico y sedimentologico del Lahar de San Nicolas en el flanco noreste del volcan Popocatepetl, BS thesis, Facultad de Ingeneria, Universidad Nacional Autonoma de Mexico, 110 p.\n||Yes\n||No\n||Maps\n|
|2001\n||Straub, S. M., Martin-Del Pozzo, A. L., 2001. The significance of phenocryst diversity in tephra from recent eruptions at Popocatepetl volcano (Mexico), Contrib. Mineral. Petrol. 140 , p. 487-510, #3506 in GERMS database\n||Yes\n||Yes\n||Description\n|
|2001\n||Cervantes de la Cruz., Karina Elizabeth, 2001. La pomez blanca intermedia: deposito producido por una erupcion plinana-subpliniana del volcan Nevado de Toluca hace 12,100 anos, Master’s thesis, Postgrado en Ciencias de la Tierra, Universidad Nacional Autonoma de Mexico, 84 p.\n||Yes\n||Yes\n||Description, maps\n|
|2001\n||Velasco Tapia, Fernando, 2001. Aspectos geoestadisticos en geoquimica analitica: Applicacion en el modelado geoquimico e isotopico de la sierra de Chichinautzin, Cinturon Volcanico Mexicano, Phd thesis: Doctor en ciencias (geoquimica), Postgrado en ciencias de la tierra, Universidad Nacional Autonoma de Mexico (Instituto de Geofisica), 273 p.\n||Yes\n||Yes\n||Table, maps\n|
|2004\n||Siebe, Claus, Rodriguez-Lara, V., Schaaf, P., Abrams M., 2004. Geochemistry, Sr-Nd isotope composition and tectonic setting of Holocene Pelado, Guespalapa and Chichinautzin scoria cones, south of Mexico City, Journal of Volcanology and Geothermal Research,Volume 130 , p. 197-226, #6862 in GERMS database\n||Yes\n||Yes\n||Table, maps\n|
|2004\n||Arana Salinas, L., 2004. Geologia de los volcanes monogeneticos Teuhtli, Tlaloc, Tlacotenco, Ocusacayo y Cuauhtzin en la Sierra Chichinautzin, al Sur de la Ciudad de Mexico, Master’s thesis (Vulcanologia), Postgrado en Ciencias de la Tierra, Universidad Nacional Autonoma de Mexico, 117 p.\n||Yes\n||Yes\n||Maps, description\n|
|2004\n||Raymundo G. Martinez-Serrano et al., 2004. Sr, Nd and Pb isotope and geochemical data from the Quaternary Nevado de Toluca volcano, a source of recent adakitic magmatism, and the Tenango Volcanic Field, Mexico, Journal of Volcanology and Geothermal Research, Volume 138, Issues 1-2, 15 November 2004, p.77-110\n||Yes\n||Yes\n||Table, maps\n|
|2005\n||Witter J. B., Kress V. C., Newhall C. G., 2005. Volcan Popocatepetl, Mexico. Petrology, Magma Mixing, And Immediate Sources Of Volatiles For The 1994-Present Eruption, J. Petrol. 46 , p. 2337-2366, #8497 in Germs database\n||Yes\n||Yes\n||Description\n|
|2005\n||Schaaf, Peter, Jim Stimac, Claus Siebes and Jose Luis Macias, 2005. Geochemical Evidence for Mantle Origin and Crustal Processes in Volcanic Rocks from Popocatépetl and Surrounding Monogenetic Volcanoe; Central Mexico, Journal of Petrology, Volume 46, #6, p. 1243-1282\n||Yes\n||Yes\n||Table\n|
|2006\n||Ceballos, Giovanni Sosa, 2006. El Paleo-Popocatepetl: petrologia, geoquimica e isotopia de secuencias pre 23, 000 anos, Master’s thesis, Postgrado en Ciencias de la Tierra, Universidad Nacional Autonoma de Mexico (Colegio de Geografia), 120 p.\n||Yes\n||Yes\n||Description, maps\n|
|2008\n||Antonio, Marco, 2008. Reconstrucción del evento eruptivo asociado al emplazamiento del flujo piroclástico El Refugio hace 13 ka, volcán Nevado de Toluca (México), Revista Mexicana de Ciencias Geologicas, V.25, # 1, 2008, p.115-147\n||Yes\n||Yes\n||Description, maps\n|
|2008\n||Meriggi, Lorenzo, José Luis Macías, Simone Tommasini, 2008. Heterogeneous magmas of the Quaternary Sierra Chichinautzin volcanic field (central Mexico): the role of an amphibole-bearing mantle and magmatic evolution processes, HeterRevista Mexicana de Ciencias Geológicas, v. 25, #.2, p. 197-216\n||Yes\n||Yes\n||Table\n|
|2008\n||Straub, S. M., Martin-Del Pozzo, A. L., Langmuir, C.H., 2008. Evidence from High-Ni Olivines for a Hybridized peridotite/pyroxenite source for orogenic andesites from the central Mexican volcanic belt; Geochemistry Geophysics Geosystems 9, 33 p.\n||Yes\n||Yes\n||Table\n|
|2009\n||Guilbaud, M.-N., Siebe, C., Agustín-Flores, J., 2009. Eruptive style of the young high-Mg basaltic-andesite Pelagatos scoria cone southeast of México City. Bull. Volcanol. 71, 859–880.\n||Yes\n||Yes\n||Table, maps\n|
|2009\n||Augustin Flores, Javier, 2009. Geologia y petrogenesis de los volcanes monogeneticos Pelagatos, Cerro del Agua y Dos Cerros en la Sierra Chichinautzin, al sur de la Ciudad de Mexico, Master thesis: Maestria en Ciencias (Vulcanologia), Postgrado en Ciencias de la Tierra, Universidad Nacional Autonoma de Mexico (Instituto de Geofisica), 97 p.\n||Yes\n||Yes\n||Table\n|
|2010\n||Arana-Salinas, L., Claus Siebe and José Luis Macias 2010. Dynamics of the ca. 4965 yr 14C BP "Ochre Pumice" Plinian eruption of Popocatepetl volcano, Mexico, Journal of Volcanology and Geothermal Research, Volume 192, Issues 3-4, 10 May 2010, p. 212-228\n||Yes\n||Yes\n||Description\n|
|2011\n||Augustin-Flores, Javier, Claus Siebe and Marie-Noëlle Guilbaud, 2011. Geology and geochemistry of Pelagatos, Cerro del Agua, and Dos Cerros monogenetic volcanoes in the Sierra Chichinautzin Volcanic Field, south of Mexico City, Journal of Volcanology and Geothermal Research, Volume 201, Issues 1-4, 15 April 2011, p.143-162\n||Yes\n||Yes\n||Table\n|