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Geochemistry of the extensive peralkaline pyroclastic flow deposit of NW Mexico, based on conventional and handheld X-ray fluorescence. Implications in a regional context/Geoquimica del extenso deposito de flujo piroclastico hiperalcalino del NW de Mexico, basada en fluorescencia de rayos X convencional y portatil. Implicaciones en un contexto regional.

1. Introduction

In Northwestern Mexico, shortly after the Miocene Continental Volcanic Arc became inactive, a Middle Miocene magmatic event occurred, characterized by the eruption of anorogenic melts in a rift environment immediately prior to the Gulf of California opening. This volcanic event comprised some occurrences of mafic lavas with transitional signatures, but was dominated by peralkaline silicic volcanic rocks (Vidal-Solano, 2005). The peralkaline comenditic rocks crop out as lavas and pyroclastic flow deposits. Moreover, an ignimbritic sequence has been widely recognized on both sides of the Gulf of California (Fig. 1), in Baja California where it is known as the Tuff of San Felipe (Stock et al. 1999; Oskin et al. 2001; Bennett, 2009; Olguin-Villa, 2010; Olguin-Villa et al, 2010), and in the state of Sonora where it is described as peralkaline ignimbrite (Vidal Solano et al, 2005, 2007, 2008a; Barrera-Guerrero and Vidal-Solano, 2010; Gomez-Valencia and Vidal-Solano, 2010). This ignimbritic episode, whose outcrops span an area of at least 50.000 [km.sup.2], has been attributed to a possible mega-eruption that occurred during Middle Miocene time (Vidal-Solano et al, 2008b). In this paper we test a method of geochemical characterization of the peralkaline pyroclastic deposits recognized in NW Mexico (Vidal-Solano, 2012), with the aim to correlate major and trace element variations in the basal vitreous lithofacies by analyzing flat surfaces of rock slabs.

2. Methods

Geochemical methods are useful to correlate outcrops of ignimbrites that belong to the same event in different regions. However, it is important to check first that samples show no alteration and to use elements that have little mobility. Some immobile or slightly mobile trace elements can be determined by X-ray fluorescence (XRF) with great accuracy; this analytical technique is therefore useful to generate good results with low investment of time and resources. The existence of an extensive ignimbrite unit (the Tuff of San Felipe in Baja California and Middle Miocene ignimbrites near Hermosillo), which crops out over an area of at least 50 000 [Km.sup.2] in NW Mexico, has been attributed to a possible mega-eruption during Middle Miocene time (Vidal-Solano et al, 2008a). Until now, the correlations between the different outcrops located both in Sonora and Baja California were based on paleomagnetic studies (Oskin et al, 2001; Hernandez-Mendez et al, 2008, Stock et al, 2008), which have shown similar magnetization and an unusual direction for Middle Miocene time (Olguin-Villa et al, 2010). Geochemical analyses of pyroclastic flow deposits may show erratic variations in some elements, due to: 1) the use of whole rock samples that, in the case of ignimbrites, can contain fragments of alien or mixed liquids, and, 2) the poor representativeness of the samples with the required chemical data, because the cost of these analytical techniques restricts the number of analyses (Vidal-Solano and Meza-Figueroa, 2009).

In this work we have used both WD-XRF and ED-XRF techniques to obtain the geochemical data on the surface of rock chips remaining after preparation of thin sections. The analytical method is carried out in a specific point of small size and well located on the surface rock. This method is highly useful, because it allows us to determine original compositions of magmas by analyses of the rock surface which is free from exotic fragments. In addition, such a method represents a very low cost investment in sample collection and preparation for the analysis, because the hand specimen can be re-used and only requires minimal preparation. Furthermore, the time needed on the analytical equipment is minimal; the procedure is very efficient and yields results that are useful complements to the initial petrographic study.

3. Analytical Techniques

Analyses reported in this study were carried out at the X-ray Fluorescence Laboratory and the Environmental Geochemistry Laboratory of the Universidad Nacional Autonoma de Mexico, using a Siemens SRS 3000 WDXRF sequential spectrometer and a Thermo Scientific portable analyzer ED-XRF Niton XL3T. The SRS 3000 spectrometer was used to measure the trace elements Rb, Sr, Ba, Y, Zr, Nb, V, Cr, Co, Ni, Cu, Zn, Th and Pb, under the analytical and reference materials used in the construction of calibration curves reported in Lozano and Bemal (2005). To shorten the total measurement time, an adjustment was made spending only 20 seconds per point, reducing therefore the time per sample to ca. 15 min. With the Niton XL3T spectrometer we measured Rb, Sr, Zr, Zn and Pb, but also some major elements like Mn, Ti, Fe, Ca and K on three different areas of one square centimeter on each rock slab. All these values were corrected using standard analysis of the IGL series (IGLSY, IGLA-1 and IGLS-1) and RGM-1. The total measurement time per sample was 3 minutes, and the variables of the analysis are reported in Zamora et al. (2008). IGLA-1 and RGM-1 were analyzed by both techniques under the same conditions in order to assure that analytical results were well calibrated. Trace elements measured with the SRS3000 showed an excellent agreement between measured and certified values with a mean accuracy of 93.4%. Values for IGLA-1 reported by Niton showed for Fe, Ca and K a mean accuracy of 88% calculated by A=100-Abs[(True value-Meas value)/Meas value)*100)].

[FIGURE 1 OMITTED]

Sample preparation

The sample preparation consists in smoothing, cleaning and drying the surface of each slab to expose the flat side to the x-ray. This is not difficult because after the preparation of thin sections the slabs already had a flat surface, as well as a suitable size to adjust them on the sample loader of the SRS 3000 spectrometer (Fig. 2). Samples smaller than 34 mm were mounted on a plastic film inert to X-rays (mylar) prior to the analysis.

[FIGURE 2 OMITTED]

4. Studied material

We studied 35 slabs of peralkaline rocks: 22 samples of vitrophyre facies of the ignimbritic deposits and 13 samples of glassy facies of porphyritic rhyolitic lava flows having the same chemical affinity. One sample of a metaluminous rhyolite was also analyzed for reference. The ignimbritic samples are slightly porphyritic (<15% phenocrysts), with different degrees of welding yielding vitroclastic to eutaxitic textures (Fig. 2). Their mineralogical association is characterized by the presence, in order of abundance, of Na-sanidine, greenish iron-rich ferrohedenbergite and fayalite. Plagioclase and hydrous minerals such as biotite or amphibole are never present in these lavas. This distinctive mineral association characterizes comendite-type high-silica rhyolites (Vidal-Solano et al., 2007). Chemically, these rocks have, unlike the metaluminous rhyolites, high Si[O.sub.2] (> 72%) and alkali values (7-9 %), but low alumina (< 12 %) giving rise to their peralkaline affinity, and relatively high iron contents (Table 1, Vidal-Solano et al, 2005, 2007, 2008b). Another important feature is their high concentration in Rb and Zr, and very low values in Sr and Ba.

5. Results

The peralkaline rhyolitic lavas and the metaluminous rhyolite were used as references for the geochemical discrimination. The results are reported in Tables 1 and 2. Zr, Sr, Rb, Pb, Zn, Ba, Nb, Th, determined by WD-XRF sequential spectrometry, and Zr, Sr, Rb, Pb, Zn, Mn, Ti, Ba, [Fe.sub.2][O.sub.3]t, CaO and [K.sub.2]O, determined by ED-XRF spectrometry, show concentrations and ratios consistent with the values obtained by ICP-MS analyses on whole rock samples (Vidal-Solano et al, 2005, 2007, 2008b, Olguin-Villa, 2010). The concentrations of these elements were reported on binary, ternary and multi-element diagrams to better visualize the relationships and variations among the different samples (Fig. 3 and 4).

All the samples of the peralkaline rhyolite (ignimbrites and lavas) retain similar element ratios (Fig. 3A): low Sr and Ba, high Rb and Th, and moderate concentrations in Nb and Zr compared to the metaluminous rhyolite. Parallelism of the spectra in this diagram indicates a genetic link for all the peralkaline samples. However, a difference does exist between the concentrations in the ignimbrites and those in the lavas. This is best illustrated on the diagram of Figure 3B, which shows the clustering of the ignimbrite samples, suggesting a good correlation between ignimbrite outcrops, and a wide dispersion of the points representing the rhyolite lava flows. The ratios between Rb, [K.sub.2]O, Sr, and [Fe.sub.2][O.sub.3] concentrations for each ignimbrite sample are plotted in Figure 4A, which allowed the distinction of different data sets. Three groups with similar chemical signature can be defined, suggesting a common source for samples from different outcrops; this in turn leads to a more precise correlation of the different units.

5.1. Geochemistry

The major element analyses show that the ignimbrite samples have high but variable concentrations in [K.sub.2]O (2 to 5%) and low CaO contents (<1%). Total [Fe.sub.2][O.sub.3] values are generally higher than 1% and increase when Mn and Ti increase. This is also a criterion that differentiates peralkaline rhyolites from metaluminous ones (Vidal-Solano, 2005).

The trace element characteristics are best visualized on a multi-element diagram (Fig. 3). Incompatible multi-element patterns, normalized to N-MORB (Pearce, 1983), of the peralkaline ignimbrites exhibit an overall parallelism of the spectra (Fig. 3A), with irregular patterns characterized by pronounced peaks in Rb and Th, moderate peaks in Nb and Zr, and negative anomalies in Ba and Sr, due to feldspar fractionation. The rhyolitic lavas present similar patterns, but more pronounced negative anomalies and a higher degree of enrichment in Nb and Zr. The parallelism of the spectra of ignimbrites and rhyolites supports a common source for all the peralkaline samples. It is also noted that it is possible to differentiate between the concentrations of the rhyolitic ignimbrite and lava flow samples. The ratio between concentrations of elements in the peralkaline rhyolites, which is visibly different from one of the metaluminous rhyolites analyzed, imparts in these lavas a unique geochemical identity (Fig. 3A).

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

Concentrations of incompatible and immobile elements Nb, Zr and Th, called HFSE (High Field Strength Elements), are highly variable for the rhyolitic samples, while the points representing the ignimbrite samples plot in a limited area (Fig. 3B) illustrating a good correlation between all the studied ignimbrite outcrops.

For a better chemical discrimination we plot on ternary diagrams trace and major elements with sufficient abundance in these rocks (Fig. 4). On the Rb/K2O-Sr-Fe2O3 diagram (Fig. 4A), we can discriminate 3 different trends: a) one corresponding to the ignimbrite and lavas from Sierra Libre, Bahia de Kino and Punta Chueca; b) a second trend corresponding to samples from Hermosillo and those from San Felipe in Baja California and finally, c) a third trend that brings together most of the Sonora and Baja California outcrops. Each group shows a strong variation in Sr contents, which can be attributed to different percentages of alkali feldspar fractionation. The distal ignimbritic deposits from Catavina (Baja California) and Rayon (Sonora), which are separated by more than 500 km, plot in the same trend. Most particularly, the vitrophyre samples from Mesa Cajon de Acuna in Rayon (Sonora) fall in the same group (with higher Sr content) as the Catavina samples (Olguin-Villa, 2010; Olguin-Villa et al., 2010, Gomez-Valencia and Vidal-Solano, 2010; Olguin-Villa et al., 2013).

6. Discussion

6.1. Reliability of the approach

Several factors can influence the reproducibility of the chemical signature of the studied samples: a) the percentage of glass and phenocrysts, b) the presence of xenocrysts and, c) the presence of xenoliths or lithic clasts. Xenoliths can be easily detected because a petrographic study is conducted at the same time on the analyzed samples. Some porphyritic samples can contain phenocrysts that come from a different liquid; these xenocrysts are not in equilibrium with the peralkaline liquid and therefore introduce discrepancies in the data. This factor is however negligible as all the vitreous samples studied in this work have more than 85% glass.

The greatest difference in composition was observed in rock slabs of Catavina pyroclastic outcrops in Baja California (Table 1 and 2, group 3 in Fig. 4A), where the same ignimbrite unit shows variations in xenocryst contents ranging from 5 to 15%. These crystals such as plagioclase, biotite, hornblende and orthopyroxene are easily identified as phenocrysts because they do not correspond to the mineral phase association observed in peralkaline magmatism. In accord with previous analysis, results obtained by this approach on obsidians at the base of some peralkaline rhyolitic lava flows show also low Sr values that can be related to different percentages of alkali feldspar fractionation. Excellent geochemical correlations as well as characterization of major and trace element variations in the peralkaline pyroclastic deposits were obtained by analyzing flat surfaces of rock slabs, giving evidence of the reliability of this approach.

6.2. Regional implications

The variations of the concentrations in Zr, Pb, Zn, Mn and Ti (Figs. 4B, C, D, E and F) established that ignimbrite samples range from low values (except for Zn which has a reverse behavior) in thicker deposits such as those of Sierra Libre or Kino Bay, up to higher values in the distal deposits of reduced thickness that correspond to the boundary of the ignimbrite exposures, such as those of the Rayon and Catavina areas (Fig. 1). During a sustained large-volume eruption, successive asymmetric lobes of an ignimbrite may develop in different locations (Branney and Kokelaar, 2002). Sequentially developed regional lobes may be difficult to distinguish within an extensive ignimbrite sheet, but can be revealed by detailed fieldwork coupled with petrographic analysis in cases where the composition of the eruption or included lithic clasts changed with time (e.g. Bishop Tuff; Wilson & Hildreth 1997). Such a distribution of the thickness and chemical variations suggest that all of these peralkaline pyroclastic flow deposits in NW Mexico are directly associated and related to a unique and large event (mega-eruption). Oskin (2002) and Oskin and Stock (2003) proposed that the vent area of the Tuff of San Felipe was located at Punta Chueca, north of Kino Bay, because of the unusual characteristics of the base of the deposit. In that location the ignimbrite does not have a defined base, with a vitrophyre, but rather appears to continue downward into fluidal rhyolites, suggesting that the ignimbrite corresponds to an intracaldera facies rather than an outflow sheet. Although the ignimbrite does have a basal vitrophyre in one part of the Sierra Libre, we consider Sierra Libre as a more appropriate vent location, because great volumes of peralkaline rhyolite lavas have been found there in clear stratigraphic relationship with peralkaline ignimbrites (Barrera-Guerrero and Vidal-Solano, 2010; Barrera-Guerrero, 2012). The chemical variations and the geographic distribution of ignimbrite deposits may suggest that they are related to a zoned magma reservoir. The detailed relationships of the lavas with the ignimbrite at Punta Chueca and at Sierra Libre, and the interpretation of the basal relationships of the ignimbrite in the vicinity of these two locations, remain to be determined. Nevertheless, we propose that both of these regions were originally adjacent and part of the same vent system or at least the same volcanic field. Our proposal is based on stratigraphic and geochemical correlation of the peralkaline units in the volcanic sequence of both regions.

An excellent correlation is observed for group 1 ignimbrites (Fig. 4) that comprise the Sierra Libre and Kino Bay outcrops, which are separated by more than 100 km. Recently, Bennett (2009) has proposed the existence of a rapid Late Miocene west-northwest-directed transtensional displacement across the Kino Bay area, which could represent some of the Pacific-North America (PAC-NAM) plate boundary deformation. However, this dextral shear zone localized within the Kino Bay area is not sufficient to successfully accommodate the ~150 km missing after the paleo-tectonic restoration of the post-6.1 Ma PAC-NAM plate boundary position (Oskin et al., 2001). On the basis of the chemical correlations, and our existing understanding of the basal characteristics of the ignimbrite, we propose the existence of dextral faults between Kino Bay and Sierra Libre, which may have displaced crustal blocks during a period of strong tectonic activity (12-6 Ma) related to a proto-Gulf transtensional episode (Fig. 1). The outcrop distribution of the Sonora samples suggests a displacement of at least 100 km that affected the ignimbrites of coastal Sonora, during a Late Miocene transtensional event prior to the opening of the Gulf of California. This major structure would now be buried by the large amount of sediment that has been deposited in recent deltas on the Sonora coast.

7. Conclusions

The combination of analytical methods applied in this work lead to several main conclusions [i] WD-XRF and ED-XRF analyses of surfaces of rock slabs are an excellent complement to the petrological characterization of vitreous samples, particularly those from pyroclastic density current deposits in which the lithic influence on whole rock analysis cannot be ignored. [ii] This kind of analysis allows us to determine the peralkaline character of the Middle Miocene anorogenic rhyolites (ignimbrites and lava flows) and to discriminate them from the metaluminous rhyolites. [iii] By applying this method to the regional ignimbrites, we are able to correlate localities separated by hundreds of kilometers, supporting the hypothesis that all the studied ignimbrite vitrophyres stem from a unique mega-eruption. [iv] Our regional correlations suggest displacement (up to more than 100 Km) between some of the thickest ignimbrite deposits, which we attribute to now-buried dextral faults related to the proto-Gulf of California opening during Middle-Late Miocene time.

http://dx.doi.org/10.5209/rev_JIGE.2013.v39.n1.41754

Acknowledgements

This work was supported by a Research Grant #061198 from Consejo Nacional de Ciencia y Tecnologia (CONACYT) to Jesus Roberto Vidal Solano. Thanks to Sheila A. Corrales (Departamento de Geologia de la Universidad de Sonora) for thin-section and rock slab preparation. J. Stock's participation was supported by the US National Science Foundation grant EAR-0911761. The authors wish to thank reviewers Dr. Takeshi Kuritani and Dr. Manoj. K. Pandit for valuable comments that have enriched this work. Likewise, the detailed and careful comments of Dr. Alain Demant are greatly appreciated.

References

Barrera-Guerrero, S. (2012): Contribucion al estudio del evento volcanico hiperalcalino del Mioceno Medio en el NW de Mexico: Petrologia de la Sierra Libre, Sonora. (M.S. thesis): Departamento de Geologia, Universidad de Sonora, 114pp.

Barrera-Guerrero, S., Vidal-Solano J.R. (2010): Reconocimiento del volcanismo hiperalcalino de edad Mioceno Medio en el NW de Mexico: Un registro completo en La Sierra Libre, Sonora, Mexico. XX

Congreso Nacional de Geoquimica, Temixco, Morelos, Mexico. Actas INAGEQ, 16, 229-234.

Bennett, S. (2009): Transtensional Rifting in the Late Proto-Gulf of California Near Bahia Kino, Sonora, Mexico. (M.S. thesis): University of North Carolina at Chapel Hill, 122 p.

Branney, M. J., Kokelaar, P. (2002): Pyroclastic Density Currents and the Sedimentation of Ignimbrites. Geological Society, London, Memoirs, 27.

Gomez-Valencia A. M., Vidal-Solano J.R. (2010): Los depositos ignimbriticos anorogenicos en Rayon, Sonora: Correlacion con el volcanismo hiperalcalino del Mioceno Medio en el NW de Mexico. XX

Congreso Nacional de Geoquimica, Temixco, Morelos, Mexico: Actas INAGEQ, 16, 241-246.

Hernandez-Mendez, G.L., Stock, J., Vidal-Solano, J., Paz-Moreno, F.A. (2008): Paleomagnetic constraints on the extent of the Miocene Tuff of San Felipe/Tuff of Hermosillo, Sonora, Mexico. Abstract 197-2, Geological Society of America Abstracts with Programs 40(6), 264.

Lozano, R., Bernal, J.P. (2005): Assessment of a new set of geochemical reference materials for XRF major and trace element analysis. Revista Mexicana de Ciencias Geologicas, 22, 329-344.

Lozano, R., Vidal-Solano, J.R., Zamora, O., Mendoza-Cordova, A. (2010): Determinacion de elementos traza por FRX en vidrios volcanicos mediante el analisis de "testigos" de laminas delgadas: Identidad geoquimica de las riolitas hiperalcalinas del NW de Mexico. XX Congreso Nacional de Geoquimica, Temixco, Morelos, Mexico: Actas INAGEQ, 16, 170-175.

Olguin-Villa, A.E. (2010): Estudio fisico y quimico del volcanismo hiperalcalino en la region de Catavina, Baja California. Tesis de Licenciatura, Universidad de Sonora, 84 p.

Olguin-Villa, A.E. (2013): Establecimiento de la estratigrafia magnetica del evento volcanico hiperalcalino del Mioceno Medio en la Sierra Libre, Sonora, Mexico. (M.S. thesis): Departamento de Geologia, Universidad de Sonora, Mexico, 76pp.

Olguin-Villa, A.E., Vidal-Solano, J.R., Stock, J.M. (2010): Geoquimica del volcanismo felsico de edad Mioceno medio en la region de Catavina: significado del volcanismo hiperalcalino en Baja California, Mexico. XX Congreso Nacional de Geoquimica, Temixco, Morelos, Mexico: Actas INAGEQ, 16, 247-252.

Olguin-Villa, A.E., Vidal-Solano, J.R., Stock J.M. (2013): Petrografia, geoquimica, petro-fabrica y paleomagnetismo de la Toba de San Felipe en la region de Catavina, Baja California, Mexico. Revista Mexicana de Ciencias Geologicas, 30, in press.

Oskin, M.E. (2002): Tectonic evolution of the northern Gulf of California, Mexico, deduced from conjugate rifted margins of the upper Delfin Basin. PhD thesis California Institute of Technology, Pasadena, 487 p.

Oskin, M, Stock, J., Martin-Barajas, A. (2001): Rapid localization of Pacific-North America plate motion in the Gulf of California. Geology, 29, 459-462. doi:10.1130/0091-7613(2001)029<0459:RLOPNA >2.0.CO;2

Oskin M.E., Stock J.M., (2003): Cenozoic volcanism and tectonics of the continental margins of the Upper Delfin basin, northeastern Baja California and western Sonora. In S.E. Johnson, S.R. Patterson, J.M. Fletcher, G.H. Girty, D.L. Kimbrough & A. Martin-Barajas (Eds.), Tectonic evolution of northwestern Mexico and the southwestern USA. Geol. Soc. Am. Spec. Paper 374, 421-438. doi:10.1130/0-8137-2374-4.421

Pearce, J.A. (1983): Role of the sub-continental lithosphere in magma genesis at active continental margins, In Hawkesworth, C. J. and Norry, M. J. eds., Continental basalts and mantle Xenoliths, 230-250, Shiva, Nantwich, Cheshire, U.K.

Stock, J.M., Lewis, C.J., Nagy, E.A. (1999): The Tuff of San Felipe: an extensive Middle Miocene pyroclastic flow deposit in Baja California, Mexico, Journal of Volcanology and Geothermal Research, 93, 53-74. doi:10.1016/S0377-0273(99)00079-7

Stock, J.M., Martin-Barajas, J.A., Chapman, A., Lopez-Martinez, M. (2008): Net Slip across the Ballenas Transform Fault Measured from Offset Ignimbrite deposits. EOS Trans. American Geophysical Union, Fall Meeting Supplement, 89(53), abstract #T11A-1853.

Vidal-Solano, J.R. (2005): Le volcanisme hyperalcalin d'age Miocene Moyen du Nord-Ouest du Mexique (Sonora): Mineralogie, Geochimie, cadre geodynamique. Ph.D. Thesis, Universite Paul Cezanne, 256p.

Vidal-Solano, J.R. (2012): Estudio petrologico de los Paleo-Volcanes hiperalcalinos de Sonora, Mexico. Epistemus, 13, 21-26.

Vidal-Solano, J.R., Paz-Moreno, F.A., Iriondo, A., Demant, A., Cocheme, J.J. (2005): Middle Miocene peralkaline ignimbrites in the Hermosillo region (Sonora, Mexico): Geodynamic implications. C. R. Geoscience, 337, 1393-1582. doi:10.1016/j.crte.2005.08.007

Vidal-Solano, J.R., Paz-Moreno, F.A., Demant, A., Lopez-Martinez, M. (2007): Ignimbritas hiperalcalinas del Mioceno medio en Sonora Central; Revaluacion de la estratigrafia y significado del volcanismo Terciario. Revista Mexicana de Ciencias Geologicas, 24, 47-67.

Vidal-Solano, J.R., Stock, J.M., Iriondo, A., Paz-Moreno, F.A. (2008a): Las ignimbritas hiperalcalinas del NW de Mexico: Una mega erupcion durante el Mioceno medio?. Reunion Anual de la Union Geofisica Mexicana, Pto. Vallarta, Jalisco, Mexico. Geos, 28, p. 218.

Vidal-Solano, J.R., Demant A., Paz-Moreno, F.A., Lapierre, H., Ortega-Rivera M.A., Lee, J.K.W. (2008b): Insights into the tectonomagmatic evolution of NW Mexico: Geochronology and geochemistry of the Miocene volcanic rocks from the Pinacate area, Sonora. Geological Society of America Bulletin, 120, 691-708. doi:10.1130/B26053.1

Vidal-Solano J.R. y Meza-Figueroa D.M. (2009): En busqueda de una correlacion geoquimica para las ignimbritas hiperalcalinas del Mioceno Medio en el NW de Mexico: Avances en el analisis de laminas delgadas con ICP-AES y un sistema de ablacion laser acoplado. XIX Congreso Nacional de Geoquimica, Ensenada, Baja California, Mexico. Actas INAGEQ, 15 (1), 50-51.

Wilson, C. J. N., Hildreth, W. (1997). The Bishop Tuff: new insights from eruptive stratigraphy. Journal of Geology, 105, 407-439. doi:10.1086/515937

Zamora Martinez, O., Martin Romero, F., Lozano Santa Cruz, R. (2008): Evaluacion del desempeno de un analizador portatil de Fluorescencia de Rayos X en la determinacion de la composicion elemental de residuos mineros. Reunion Anual de la Union Geofisica Mexicana, Pto. Vallarta, Jalisco, Mexico. Geos, 28 (2), p-161.

J.R. Vidal-Solano (1) *, R. Lozano Santa Cruz (2), O. Zamora (3), A. Mendoza- Cordova (1), J.M. Stock (4)

(1) Area de FRX, Laboratorio de Cristalografia y Geoquimica del Departamento de Geologia, Universidad de Sonora, 83000 Hermosillo, Sonora, Mexico

(2) Laboratorio de FRX del Instituto de Geologia de la Universidad Nacional Autonoma de Mexico, D.F, Mexico.

(3) Laboratorio de Geoquimica Ambiental del Instituto de Geologia de la Universidad Nacional Autonoma de Mexico, D.F., Mexico

(4) California Institute of Technology, Seismo Lab 170-25, 1200 E. California Blvd., Pasadena CA 91125 USA

* Corresponding author: jrvidal@ciencias.uson.mx

Received: 26/04/2011 / Accepted: 12/04/2013
Table 1.-Trace element concentrations determined in the rhyolite
slabs studied by WD-XRF spectrometer. (*) Major element
concentrations determined in whole rock by ICP-AES (Vidal-Solano,
2005; Vidal-Solano et al., 2005; Vidal-Solano et al., 2008a, 2008b;
Olguin-Villa 2010). Sample locations are given in WGS84.

Tabla 1.-Concentraciones de elementos traza determinadas en las
secciones de las riolitas estudiadas bajo un espectrometro WD-FRX.
(*) Concentraciones de elementos mayores determinados en roca total
por ICP-AES (Vidal-Solano, 2005; Vidal-Solano et al., 2005;
Vidal-Solano et al., 2008a, 2008b; Olguin-Villa 2010). Coordenadas
de las muestras en el datum WGS-84.

Sample            Rhyolite type    UTM East    UTM North

EP071A SLAB        Ignimbrite     12R 517371    3165548
EPVV10-01A SLAB       Lava        12R289107     3526447
SLEC07A SLAB          Lava        12R 512172    3168291
SLEG19 SLAB           Lava        12R 511341    3167978
SLEG17A SLAB          Lava        12R 511511    3167685
SLEG17B SLAB          Lava        12R 511512    3167686
EPVV01B SLAB          Lava        12R289107     3526447
EPVV01A SLAB          Lava        12R289107     3526447
EH1001 SLAB           Lava        12R482091     3208159
SLEC7B SLAB           Lava        12R 512172    3168291
EG073 SLAB         Ignimbrite     12R 544361    3243156
MCR1001A SLAB      Ignimbrite     12R530160     3276607
CEJ071 SLAB        Ignimbrite     12R484989     3287559
PAR1002A SLAB      Ignimbrite     12R530632     3275303
EG075 SLAB         Ignimbrite     12R 544361    3243156
DEL0802D SLAB      Ignimbrite     11R708533     3402097
DEL0802B SLAB      Ignimbrite     11R 708534    3402098
SA0911B SLAB       Ignimbrite     HR 689374     3311426
MEC092A1 SLAB      Ignimbrite     HR 707505     3305646
MEC092A SLAB       Ignimbrite     HR 707505     3305646
MEC091A SLAB       Ignimbrite     HR 707505     3305646
CEU091B SLAB       Ignimbrite     12R401865     3195911
CEU091B1 SLAB      Ignimbrite     12R 401866    3195912
LPSL093 SLAB          Lava        12R503562     3162260
LMCR093A SLAB      Ignimbrite     HR 526131     3291842
MCDA094A SLAB      Ignimbrite     12R527679     3284565
MEC0901B SLAB      Ignimbrite     HR 707505     3305646
SA0911A SLAB       Ignimbrite     HR 689374     3311426
PP0906 SLAB           Lava        12R394164     3206028
EP0703 SLAB           Lava        12R517475     3165442
PP0909 SLAB        Ignimbrite     12R394166     3206030
SA0912L SLAB       Ignimbrite     HR 689375     3311427
PP0901 SLAB           Lava        12R394164     3206028
CEY0902 SLAB       Ignimbrite     12R500727     3204376

                                      Zr    Sr    Rb    Pb    Zn    Ba
Sample                Locality        ppm   ppm   ppm   ppm   ppm   ppm

EP071A SLAB       Sierra Libre Son.   357   69    462   34    347   47
EPVV10-01A SLAB   El Pinacate Son.    798    7    146   26    141   90
SLEC07A SLAB      Sierra Libre Son.   636    1    147   29    139   111
SLEG19 SLAB       Sierra Libre Son.   763    0    162   29    166   13
SLEG17A SLAB      Sierra Libre Son.   619    1    156   26    147   92
SLEG17B SLAB      Sierra Libre Son.   611    2    152   28    140   98
EPVV01B SLAB      El Pinacate Son.    802    6    151   25    145   89
EPVV01A SLAB      El Pinacate Son.    794    6    148   24    142   79
EH1001 SLAB        Hermosillo Son.    652    2    179   17    137    9
SLEC7B SLAB       Sierra Libre Son.   512    1    114   17    108   83
EG073 SLAB         El Gavilan Son.    340   24    219   31    119   31
MCR1001A SLAB        Rayon Son.       349   35    214   36    105   84
CEJ071 SLAB        C. La Ceja Son.    336   28    219   31    99    67
PAR1002A SLAB        Rayon Son.       316   33    219   33    106   57
EG075 SLAB         El Gavilan Son.    314   11    225   33    119   33
DEL0802D SLAB      San Felipe B.C.    317   17    220   30    98    46
DEL0802B SLAB      San Felipe B.C.    327   13    224   29    101   47
SA0911B SLAB        Catavina B.C.     319   102   192   27    82    144
MEC092A1 SLAB       Catavina B.C.     298   91    182   35    103   124
MEC092A SLAB        Catavina B.C.     287   88    182   36    101   89
MEC091A SLAB        Catavina B.C.     333   60    196   30    99    105
CEU091B SLAB        B. Kino Son.      365   146   261   35    283   59
CEU091B1 SLAB       B. Kino Son.      361   130   257   33    257   62
LPSL093 SLAB      Sierra Libre Son.   580    1    322   28    152   25
LMCR093A SLAB        Rayon Son.       314   34    207   31    89    72
MCDA094A SLAB        Rayon Son.       368   99    186   39    114   71
MEC0901B SLAB       Catavina B.C.     306   82    187   34    93    327
SA0911A SLAB        Catavina B.C.     289   113   186   29    82    160
PP0906 SLAB       Punta Chueca Son.   208   553   80    14    57    654
EP0703 SLAB       Sierra Libre Son.   824   58    507   29    422   27
PP0909 SLAB       Punta Chueca Son.   305   20    198   35    82    49
SA0912L SLAB        Catavina B.C.     297   70    197   35    100   72
PP0901 SLAB       Punta Chueca Son.   247   215   232   24    79    565
CEY0902 SLAB       Hermosillo Son.    343   110   234   28    118   56

                  Nb    Th    Si02 *   Ti02 *   AI203 *   Fe203 *
Sample            ppm   ppm     %        %         %         %

EP071A SLAB       33    37
EPVV10-01A SLAB   57    19    74.25     0.46     11.41     1.91
SLEC07A SLAB      34    14
SLEG19 SLAB       39    16
SLEG17A SLAB      34    15
SLEG17B SLAB      34    14
EPVV01B SLAB      58    19    75.89     0.20     11.23     2.11
EPVV01A SLAB      58    20
EH1001 SLAB       45    18
SLEC7B SLAB       27    11
EG073 SLAB        31    27    72.77     0.12     12.01     1.05
MCR1001A SLAB     31    23
CEJ071 SLAB       30    24
PAR1002A SLAB     30    24
EG075 SLAB        30    24
DEL0802D SLAB     29    21    72.20     0.10     12.30     1.70
DEL0802B SLAB     30    25    71.90     0.10     12.30     1.70
SA0911B SLAB      26    20    71.70     0.16     11.80     1.98
MEC092A1 SLAB     28    22
MEC092A SLAB      27    23
MEC091A SLAB      29    22
CEU091B SLAB      29    34
CEU091B1 SLAB     29    32
LPSL093 SLAB      39    13
LMCR093A SLAB     31    22
MCDA094A SLAB     33    26
MEC0901B SLAB     29    21    75.80     0.13     11.40     1.78
SA0911A SLAB      28    21    74.20     0.16     12.35     2.12
PP0906 SLAB        9     5
EP0703 SLAB       41    25
PP0909 SLAB       27    21
SA0912L SLAB      28    21    72.00     0.14     11.75     1.88
PP0901 SLAB       16    24
CEY0902 SLAB      29    26    72.88     0.15     12.20     0.77

                  MgO *   CaO *    Na20 *    K20 *
Sample              %       %        %        %

EP071A SLAB
EPVV10-01A SLAB   0.08    0.42     5.35      4.70
SLEC07A SLAB
SLEG19 SLAB
SLEG17A SLAB
SLEG17B SLAB
EPVV01B SLAB      0.08    0.45     3.78      3.65
EPVV01A SLAB
EH1001 SLAB
SLEC7B SLAB
EG073 SLAB        0.07    0.05     3.46      4.73
MCR1001A SLAB
CEJ071 SLAB
PAR1002A SLAB
EG075 SLAB
DEL0802D SLAB     0.10    0.60     4.60      3.30
DEL0802B SLAB     0.10    0.60     4.40      3.50
SA0911B SLAB      0.67    1.32     3.24      4.31
MEC092A1 SLAB
MEC092A SLAB
MEC091A SLAB
CEU091B SLAB
CEU091B1 SLAB
LPSL093 SLAB
LMCR093A SLAB
MCDA094A SLAB
MEC0901B SLAB     0.24    1.22     3.10      4.80
SA0911A SLAB      0.26    1.00     3.72      4.54
PP0906 SLAB
EP0703 SLAB
PP0909 SLAB
SA0912L SLAB      0.43    0.84     2.92      4.83
PP0901 SLAB
CEY0902 SLAB      0.13    0.52     5.23      4.53

Table 2.-Trace element and major element concentrations from rhyolite
slabs studied by a ED-XRF spectrometer. <LOD, below limit of
detection.

Tabla 2.-Concentracion de elementos traza y mayores en secciones de
riolitas, mediante espectrometro ED-FRX. <LOD, por debajo del limite
de deteccion.

Sample           Rhyolite type   UTM East    UTM North

DEL-08-02 D-1    Ignimbrite      11R708533   3402097
DEL-08-02 D-2    Ignimbrite      11R708534   3402098
DEL-08-02 D-3    Ignimbrite      11R708535   3402099
SA 09 11 B-1     Ignimbrite      11R692643   3312349
SA 09 11 B-2     Ignimbrite      11R692644   3312350
SA 09 11 B-3     Ignimbrite      11R692645   3312351
eg 07-5-1        Ignimbrite      12R544359   3243154
eg 07-5-2        Ignimbrite      12R544360   3243155
eg 07-5-3        Ignimbrite      12R544361   3243156
mec 09 01 b-1    Ignimbrite      11R707505   3305646
mec 09 01 b-2    Ignimbrite      11R707506   3305647
mec 09 01 b-3    Ignimbrite      11R707507   3305648
mlcr09-03a-1     Ignimbrite      11R526131   3291842
mlcr09-03a-2     Ignimbrite      11R526132   3291843
mlcr09-03a-3     Ignimbrite      11R526133   3291844
ceu 09b1-1       Ignimbrite      12R401865   3195911
ceu 09b1-2       Ignimbrite      12R401866   3195912
ceu 09b1-3       Ignimbrite      12R401867   3195913
pp09-06-1        Lava            12R394164   3206028
pp09-06-2        Lava            12R394165   3206029
pp09-06-3        Lava            12R394166   3206030
ep 07-03-1       Lava            12R517475   3165442
ep 07-03-2       Lava            12R517476   3165443
ep 07-03-3       Lava            12R517477   3165444
par10 02 a-1     Ignimbrite      12R530632   3275303
par10 02 a-2     Ignimbrite      12R530633   3275304
par10 02 a-3     Ignimbrite      12R530634   3275305
cej 07-1-1       Ignimbrite      12R484989   3287559
cej 07-1-2       Ignimbrite      12R484990   3287560
cej 07-1-3       Ignimbrite      12R484991   3287561
eg 07-3-1        Ignimbrite      12R544359   3243154
eg 07-3-2        Ignimbrite      12R544360   3243155
eg 07-3-3        Ignimbrite      12R544361   3243156
mcr10-01a-1      Ignimbrite      12R530160   3276607
mcr10-01a-2      Ignimbrite      12R530161   3276608
mcr10-01a-3      Ignimbrite      12R530162   3276609
mec 09-01 a-1    Ignimbrite      11R707505   3305646
mec 09-01 a-2    Ignimbrite      11R707506   3305647
mec 09-01 a-3    Ignimbrite      11R707507   3305648
ceu 09-01b-1     Ignimbrite      12R401865   3195911
ceu 09-01b-2     Ignimbrite      12R401865   3195911
ceu 09-01b-3     Ignimbrite      12R401866   3195912
mcda 09-04a-1    Ignimbrite      12R527679   3284565
mcda 09-04a-2    Ignimbrite      12R527680   3284566
mcda 09-04a-3    Ignimbrite      12R527681   3284567
sa 0912f-1       Ignimbrite      11R689374   3311426
sa 0912f-2       Ignimbrite      11R689375   3311427
sa 0912f-3       Ignimbrite      11R689376   3311428
mec 09 02 a1-1   Ignimbrite      11R707505   3305646
mec 09 02 a1-2   Ignimbrite      11R707506   3305647
mec 09 02 a1-3   Ignimbrite      11R707507   3305648
sa 09-11a-1      Ignimbrite      11R689374   3311426
sa 09-11a-2      Ignimbrite      11R689375   3311427
sa 09-11a-3      Ignimbrite      11R689376   3311428
cey 09-02-1      Ignimbrite      12R500727   3204376
cey 09-02-3      Ignimbrite      12R500728   3204377
por 08-02u-1     Ignimbrite      11R709412   3308830
por 08-02u-2     Ignimbrite      11R709413   3308831
por 08-02u-3     Ignimbrite      11R709414   3308832
pp09-09-1        Ignimbrite      12R394164   3206028
pp09-09-2        Ignimbrite      12R394165   3206029
pp09-09-3        Ignimbrite      12R394166   3206030
pp 09-01-1       Lava            12R394164   3206028
pp 09-01-2       Lava            12R394165   3206029
pp 09-01-3       Lava            12R394166   3206030
del 08-02 b-1    Ignimbrite      11R708533   3402097
del 08-02 b-2    Ignimbrite      11R708534   3402098
del 08-02 b-3    Ignimbrite      11R708535   3402099
mec 09-02 a-1    Ignimbrite      11R707505   3305646
mec 09-02 a-2    Ignimbrite      11R707506   3305647
mec 09-02 a-3    Ignimbrite      11R707507   3305648
ep 07-1a-1       Ignimbrite      12R517371   3165548
ep 07-1a-2       Ignimbrite      12R517372   3165549
ep 07-1a-3       Ignimbrite      12R517373   3165550
lpsl 09-03-1     Lava            12R503562   3162260
lpsl 09-03-2     Lava            12R503563   3162261
lpsl 09-03-3     Lava            12R503564   3162262

                                     Zr     Sr     Rb    Pb    Zn
Sample           Locality            ppm    ppm    ppm   ppm   ppm

DEL-08-02 D-1    San Felipe B.C.     265    17     142   23    53
DEL-08-02 D-2    San Felipe B.C.     272    18     145   29    61
DEL-08-02 D-3    San Felipe B.C.     200    24     112   19    51
SA 09 11 B-1     Catavina B.C.       255    71     137   28    52
SA 09 11 B-2     Catavina B.C.       319    75     125   31    55
SA 09 11 B-3     Catavina B.C.       265    84     133   24    64
eg 07-5-1        El Gavilan Son.     325    10     147   20    71
eg 07-5-2        El Gavilan Son.     259    14     142   30    79
eg 07-5-3        El Gavilan Son.     264    10     146   25    68
mec 09 01 b-1    Catavina B.C.       262    84     131   24    67
mec 09 01 b-2    Catavina B.C.       253    94     126   24    79
mec 09 01 b-3    Catavina B.C.       254    52     126   23    68
mlcr09-03a-1     Rayon Son.          265    26     146   26    65
mlcr09-03a-2     Rayon Son.          264    35     146   23    49
mlcr09-03a-3     Rayon Son.          273    23     144   21    46
ceu 09b1-1       B. Kino Son.        283    101    140   27    150
ceu 09b1-2       B. Kino Son.        270    98     135   28    136
ceu 09b1-3       B. Kino Son.        247    96     131   25    150
pp09-06-1        Punta Chueca Son.   139    457    58    11    48
pp09-06-2        Punta Chueca Son.   162    452    55    12    54
pp09-06-3        Punta Chueca Son.   151    510    58    11    37
ep 07-03-1       Sierra Libre Son.   630    13     238   22    198
ep 07-03-2       Sierra Libre Son.   629    52     217   22    230
ep 07-03-3       Sierra Libre Son.   633    19     230   21    211
par10 02 a-1     Rayon Son.          281    22     156   28    59
par10 02 a-2     Rayon Son.          360    19     148   23    77
par10 02 a-3     Rayon Son.          285    20     156   18    59
cej 07-1-1       C. La Ceja Son.     277    14     153   28    68
cej 07-1-2       C. La Ceja Son.     270    30     150   21    54
cej 07-1-3       C. La Ceja Son.     260    19     152   28    82
eg 07-3-1        El Gavilan Son.     268    17     144   27    69
eg 07-3-2        El Gavilan Son.     274    16     146   21    80
eg 07-3-3        El Gavilan Son.     275    20     143   25    83
mcr10-01a-1      Rayon Son.          271    28     151   19    56
mcr10-01a-2      Rayon Son.          390    27     147   25    64
mcr10-01a-3      Rayon Son.          284    29     145   33    68
mec 09-01 a-1    Catavina B.C.       234    47     129   29    59
mec 09-01 a-2    Catavina B.C.       253    45     138   24    66
mec 09-01 a-3    Catavina B.C.       248    50     124   22    60
ceu 09-01b-1     B. Kino Son.        273    123    132   28    174
ceu 09-01b-2     B. Kino Son.        256    98     136   28    166
ceu 09-01b-3     B. Kino Son.        266    120    134   24    146
mcda 09-04a-1    Rayon Son.          299    82     121   34    82
mcda 09-04a-2    Rayon Son.          291    76     123   35    74
mcda 09-04a-3    Rayon Son.          286    66     125   28    81
sa 0912f-1       Catavina B.C.       271    56     139   25    71
sa 0912f-2       Catavina B.C.       288    56     143   29    78
sa 0912f-3       Catavina B.C.       307    59     142   29    68
mec 09 02 a1-1   Catavina B.C.       245    71     132   30    63
mec 09 02 a1-2   Catavina B.C.       250    68     131   28    62
mec 09 02 a1-3   Catavina B.C.       389    84     124   26    76
sa 09-11a-1      Catavina B.C.       240    70     130   22    57
sa 09-11a-2      Catavina B.C.       239    79     130   18    50
sa 09-11a-3      Catavina B.C.       245    72     128   19    56
cey 09-02-1      Hermosillo. Son.    291    53     156   26    73
cey 09-02-3      Hermosillo. Son.    261    37     159   35    65
por 08-02u-1     Catavina B.C.       275    29     144   18    52
por 08-02u-2     Catavina B.C.       254    39     142   17    70
por 08-02u-3     Catavina B.C.       296    35     140   20    61
pp09-09-1        Punta Chueca Son.   244    19     143   34    59
pp09-09-2        Punta Chueca Son.   304    12     151   32    58
pp09-09-3        Punta Chueca Son.   252    12     148   32    65
pp 09-01-1       Punta Chueca Son.   210    118    183   30    56
pp 09-01-2       Punta Chueca Son.   271    180    162   30    67
pp 09-01-3       Punta Chueca Son.   180    96     172   27    53
del 08-02 b-1    San Felipe B.C.     259    10     147   24    68
del 08-02 b-2    San Felipe B.C.     282    12     150   31    57
del 08-02 b-3    San Felipe B.C.     258    12     149   28    64
mec 09-02 a-1    Catavina B.C.       204    71     119   29    57
mec 09-02 a-2    Catavina B.C.       207    69     121   28    62
mec 09-02 a-3    Catavina B.C.       223    76     121   25    62
ep 07-1a-1       Sierra Libre Son.   306    40     252   34    192
ep 07-1a-2       Sierra Libre Son.   280    62     211   24    210
ep 07-1a-3       Sierra Libre Son.   380    59     223   34    190
lpsl 09-03-1     Sierra Libre Son.   483   < LOD   214   27    84
lpsl 09-03-2     Sierra Libre Son.   493   < LOD   221   24    107
lpsl 09-03-3     Sierra Libre Son.   495   < LOD   207   23    87

                 Mn     Ti     Ba     Fe2O3     CaO    K2O
Sample           ppm   ppm     ppm      %        %      %

DEL-08-02 D-1    191   102    < LOD    0.92    0.38    3.44
DEL-08-02 D-2    230    48    < LOD    1.03    0.45    3.51
DEL-08-02 D-3    147   124    < LOD    0.82    0.42    3.52
SA 09 11 B-1     210   527    < LOD    1.17    1.18    4.34
SA 09 11 B-2     216   564    < LOD    1.1     1.09    4.17
SA 09 11 B-3     173   600    < LOD    1.09    1.08    4.34
eg 07-5-1        222   847    < LOD    1.1     0.32    5.32
eg 07-5-2        182   378    < LOD    1.12    0.39    5.13
eg 07-5-3        215   241    < LOD    0.98    0.33    5.34
mec 09 01 b-1    308   345     669     1.02    1.24    4.43
mec 09 01 b-2    460   288     558     1.04    0.89    4.36
mec 09 01 b-3    167   403    < LOD    1.01     1.5    4.5
mlcr09-03a-1     257   287    < LOD    1.06    0.39    5.22
mlcr09-03a-2     257   335    < LOD    1.09     0.4    4.83
mlcr09-03a-3     190   244    < LOD    1.03     0.4    4.92
ceu 09b1-1       184   222    < LOD    1.01    0.73    2.25
ceu 09b1-2       223   360    < LOD    1.01    0.74    2.4
ceu 09b1-3       171   461    < LOD    1.08     0.8    2.45
pp09-06-1        416   3261    903     2.19    1.99    2.17
pp09-06-2        335   3301    927     2.12    1.93    2.06
pp09-06-3        403   3145   1221     2.13     2.2    2.32
ep 07-03-1       280   623    < LOD    1.44    0.27    2.15
ep 07-03-2       171   684    < LOD    1.34    0.69     2
ep 07-03-3       282   695    < LOD    1.37    0.31    2.06
par10 02 a-1     195   668    < LOD    1.15    0.36    5.06
par10 02 a-2     214   523    < LOD    1.1     0.34    4.88
par10 02 a-3     162   158    < LOD    1.03    0.36    5.04
cej 07-1-1       188   426    < LOD    1.11    0.37    4.75
cej 07-1-2       249   423    < LOD    1.08    0.39    4.67
cej 07-1-3       159   307    < LOD    1.05    0.37    4.87
eg 07-3-1        186   248    < LOD    1.08    0.39    4.92
eg 07-3-2        188   636    < LOD    1.1     0.37    5.3
eg 07-3-3        168   271    < LOD    1.02    0.41    5.08
mcr10-01a-1      153   288    < LOD    1.1     0.28    5.16
mcr10-01a-2      202   509    < LOD    1.15    0.32    5.32
mcr10-01a-3      160   247    < LOD    1.13     0.4    5.14
mec 09-01 a-1    245   305    < LOD    1.03    0.55    4.5
mec 09-01 a-2    207   255    < LOD    1.06    0.52    4.56
mec 09-01 a-3    142   447    < LOD    1.04    0.57    4.6
ceu 09-01b-1     123   532    < LOD    1.03    0.74    2.37
ceu 09-01b-2     281   407    < LOD    1.06    0.76    2.28
ceu 09-01b-3     183   488    < LOD    1.05    0.79    2.51
mcda 09-04a-1    226   260    < LOD    1.2     0.86    3.8
mcda 09-04a-2    312   448    < LOD    1.2     0.88    3.59
mcda 09-04a-3    242   457    < LOD    1.26    0.77    3.65
sa 0912f-1       295   390    < LOD    1.27     0.6    4.62
sa 0912f-2       237   481    < LOD    1.23     0.6    4.68
sa 0912f-3       167   397    < LOD    1.26    0.69    4.53
mec 09 02 a1-1   235   384    < LOD    1.12    0.77    4.31
mec 09 02 a1-2   303   243    < LOD    1.13    0.92    4.12
mec 09 02 a1-3   298   829    < LOD    1.26    1.03    4.38
sa 09-11a-1      238   417    < LOD    1.14    1.23    3.99
sa 09-11a-2      270   640    < LOD    1.12    1.13    4.15
sa 09-11a-3      173   417    < LOD    1.11    1.07     4
cey 09-02-1      169   185    < LOD    1.01    0.42    4.25
cey 09-02-3      234   299    < LOD    1.04    0.41    4.24
por 08-02u-1     144   442     322     0.99    0.43    4.38
por 08-02u-2     268   1609    387     1.97    0.48    4.39
por 08-02u-3     237   710     362     1.17    0.44    4.58
pp09-09-1        199   229     402     0.99    1.26    4.85
pp09-09-2        275   326     410     1.05    0.62    4.49
pp09-09-3        175   342     369     0.98    0.79    4.84
pp 09-01-1       175   1185    642     1.08    0.64    3.13
pp 09-01-2       210   2764    672     1.35    1.05    2.8
pp 09-01-3       154   2189    550     1.03    0.66    2.97
del 08-02 b-1    178   357     367     1.09    0.34    3.51
del 08-02 b-2    254   253     372      1      0.35    3.76
del 08-02 b-3    235   266     376     0.99    0.34    3.52
mec 09-02 a-1    228   458    < LOD    1.07    0.73    4.52
mec 09-02 a-2    244   402    < LOD    1.09    0.82    4.48
mec 09-02 a-3    237   252    < LOD    1.08    0.77    4.36
ep 07-1a-1       198   336     314     1.13    0.58    2.96
ep 07-1a-2       181   412     219     1.16    0.64    2.82
ep 07-1a-3       233   485     273     1.29    < LOD   2.81
lpsl 09-03-1     168   220    < LOD    1.1     < LOD   4.74
lpsl 09-03-2     211   268    < LOD    1.15    < LOD   4.66
lpsl 09-03-3     179   188    < LOD    1.15    < LOD   4.53
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Title Annotation:articulo en ingles
Author:Vidal-Solano, J.R.; Cruz, R. Lozano Santa; Zamora, O.; Mendoza-Cordova, A.; Stock, J.M.
Publication:Journal of Iberian Geology
Date:Jan 1, 2013
Words:7250
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