Digital Geologic Map and Geochronologic, Geochemical and Geothermal Database of the South-Eastern Part of the Sierra Madre Occidental, Mexicoi

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Received: 24 Jul. 2018, Accepted: 19 Oct. 2018 Published online: 31 Oct. 2018 DOI: 10.22201/igg.25940694.2018.2.53.109 Volume: 2, Issue: 2, Pages: 1-6

Digital geologic map and geochronologic, geochemical and geothermal database of the south-eastern part of the Sierra Madre Occidental, MexicoI

Cartografía geológica digital y base de datos geocronológicos, geoquímicos y geotérmicos de la parte suroriental de la Sierra Madre Occidental, México

Luca Ferrari*a, Juan Carlos Castillo-Reynosoa, Teresa Orozco-Esquivela, Argelia Silva-Fragosoa

aCentro de Geociencias, Universidad Nacional Autónoma de México, Campus UNAM Juriquilla, Queretaro, 76230, Mexico

Abstract We present afirst interactive digital geological map of the southeastern part of the Sierra Madre Occidental at its borders with the Mesa Central. The area of the geological cartography covers approximately 120,000 km2 that includes part of the states of Jalisco, Zacatecas, Aguascalientes and Durango. The geology has been compiled in ArcGIS through an interpretation of all the information available in the literature, integrated with our own geological mapping. Published maps were georeferenced and, as far as possible, the traces of the geologic limits and structures with a clear morphological expression were refined using digital elevation models and satellite images available in Google Earth. The map includes 15 geological units and the main tectonic structures. The informal geological units used in the map are chronostratigraphic and lithological and are designed to highlight the main magmatic episodes that shaped the region. The age assignment for each unit has been compared with a geochronological database that includes 304 ages. The lithological classification of each polygon has been compared for consistency with a geochemical database compiled from the literature that includes 313 samples. We also added a layer of information with the main hot springs of the region and their temperature.

Keywords: Digital geologic map; Sierra Madre Occidental; geochronology and geochemical database

Resumen Presentamos un primer mapa geológico digital interactivo de la parte suroriental de la Sierra Madre Occidental en sus límites con la Mesa Central. El área cubierta por la cartografía geológica abarca aproximadamente 120,000 km2 e incluye parte de los estados de Jalisco, Zacatecas, Aguascalientes y Durango. La geología ha sido compilada en ArcGIS a través de una interpretación de toda la información disponible en la literatura e integrada con nuestra propia cartografía geológica. Los mapas publicados fueron georefe- renciados y hasta donde fue posible se corrigió la ubicación de los rasgos con una clara expresión morfológica utilizando modelos de elevación digital e imágenes satelitales disponibles en Google Earth. El mapa incluye 15 unidades geológicas y las principales estructuras tectónicas. Las unidades geológicas informales utilizadas son cronoestratigráﬁcas y litológicas y están diseñadas para destacar los principales episodios magmáticos ocurridos en la región. La asignación de la edad para cada unidad ha sido cotejada con una base de datos geocronológicos que incluye 304 edades. La clasiﬁcación litológica de cada polígono ha sido comparada por consistencia con una base de datos geoquímicos recopilados de la literatura que incluye 313 muestras. Finalmente, se ha agregado una capa de información con las principales manifestaciones termales de la región y su temperatura.

Palabras clave: Mapa geológico digital; Sierra Madre Occidental; base de datos geocronológica y geoquímica

1. Introduction I �c L. Ferrari, J. C. Castillo-Reynoso, T. Orozco-Esquivel, A. Silva-Fragoso This is an Open Access article distributed under the terms of the Creative Com- The Sierra Madre Occidental (SMO) silicic large igneous mons Attribution License (https://creativecommons.org/licenses/by-nc-sa/4.0/), province (SLIP) is one of the largest on Earth (Bryan and Fer- which permits non-commencial sharing of the work and adaptions, provided the rari, 2013). The SMO SLIP consists of silicic ignimbrites and original work is properly cited and the new creations are licensed under identi- cal terms. less rhyolitic domes with interspersed basalticﬂows mostly em- *E-mail address: [email protected] placed between the end of the Eocene and the early Miocene Terra Digitalis Volume 2, Issue2

(see Ferrari et al., 2007, for an extensive review). Also called ican Geologic Survey (Servicio Geológico Mexicano), maps in “Upper Volcanic Supergroup” (McDowell and Keizer, 1977) published papers (Loza-Aguirre et al., 2008, 2012), plus our this unusual, large volume, bimodal volcanism is accompanied own unpublishedfield mapping and observations that are partly by widespread extensional structures that are part of the “Mex- included in recent bachelor and postgraduate theses (Silva-Fra- ican Basin and Range” in its eastern part (Henry and Aranda- goso, 2015; Martínez-Reséndiz, 2016; Castillo-Reynoso, 2018). Gomez, 1992) and of the “Gulf Extensional Province” in the Thefirst step in the elaboration of the map was to define a gen- west (Gastil et al., 1975; Calmus et al., 2010). Recent works eral stratigraphy for the entire area. Based on chronostrati- have shown that the two provinces are at least partly coeval and graphic and lithologic criteria, we defined 15 informal units related to a wide rift stage that a↵ected western Mexico be- specifically designed to enhance the Cenozoic magmatic and tween 35 and 18 Ma, which preceded the focusing of extension tectonic activity and provide a synthetic view. This simplified in the region of the present Gulf of California (Ferrari et al., stratigraphy is supported by a geochronological database that 2013, 2017; Duque-Trujillo et al., 2015). includes 304 ages and a geochemical database that includes 313 The SMO SLIP covers the products of the so-called Lara- samples, both compiled from the literature and updated to July mide magmatic arc, developed between⇠100 and 45 Ma along 2018. These databases are available for download at the journal the western margin of Mexico during the subduction of the website. Published geologic maps and our unpublished cartog- Farallon plate beneath North America (McDowell et al., 2001; raphy have been reinterpreted according to the regional stratig- Henry et al., 2003; González-León et al., 2011). Also called raphy established in the previous stage. In most cases we had “Lower VolcanicComplex” (McDowell and Keizer, 1977), these to group two or more original units into a single unit, charac- rocks intrude or cover a basement which, in the southern half terized by similar lithology and age range. We also compiled of the province, consists of volcano-sedimentary terrigenous faults, folds, and volcanic vents. Published maps were georef- successions of the Guerrero Terrane and limestone represent- erenced and, as far as possible, the traces of the geologic limits ing the westernmost part of the Sierra Madre Oriental carbon- and structures with a clear morphological expression were re- ate successions (Ferrari et al., 2007). The southeastern part of fined using digital elevation models and satellite images avail- the SMO, in the states of Jalisco, Zacatecas and Durango, is able in Google Earth. Digitization was carried out with Arc- characterized by regularly spaced tectonic depressions (graben) GIS and QGIS taking special care in checking the consistency that host thermal springs, with temperatures between 35 ◦C and of the lithological classification and age assignment for each 74 ◦C, not associated to Pliocene-Quaternary silicic volcanism, unit with the geochronologic and geochemical databases. Fi- as in the conventional geothermal reservoirs exploited so far nally, we have included a layer of information with the main in Mexico. Unconventional geothermal deposits not associated hot springs of the region and their temperature based on Torres- with Neogene volcanism have been studied in France and Aus- Rodríguez et al. (1993). tralia, where the source of heat is the product of the decay of ra- dioactive isotopes (U, Th, K) naturally present in Paleozoic and 3. Map units Precambrian granites covered by layers of sediments with low thermal conductivity and low permeability (Gerner and Hol- All geologic units used in the map are lithologic informal gate, 2010; Genter et al., 2010; Siegel et al., 2014). A simi- units, the age of which have been bracketed by available iso- lar geological situation occurs in the extensional basins of the topic ages, or by their stratigraphic position. They can be di- south-eastern part of the SMO, where the upper crust is consti- vided into two broad groups: 1) Basement terranes that precede tuted by granites and silicic ignimbrites covered by continental the onset of the continental magmatism and sedimentation of sediments and where anomalous contents of U have been re- the SMO, and 2) rocks belonging to the SMO volcanic activity ported in some areas (e.g., Bryan et al., 2008). and associated continental sedimentary deposits. Rocks pre- As afirst step in an interdisciplinary project aimed at under- dating the SMO SLIP belong to the Laramide Arc, the Sierra standing the nature of the thermal waters present in the south- Madre Oriental and the Guerrero terrane. Each map unit is eastern SMO (UNAM-DGAPA-PAPIIT 100117), we have con- briefly described in Table 1. structed thefirst interactive digital geological map of this region. The area of the geological cartography covers approximately 120,000 km2 that includes part of the states of Jalisco, 4. Main geologic aspects of the map Zacatecas, Aguascalientes and Durango. From the geologic The map of the southeastern part of the Sierra Madre Oc- point of view the map also include the westernmost part of the cidental and the associated geochronologic and geochemical Mesa Central and the northernmost part of the Trans-Mexican databases presented in this work show several interesting as- Volcanic Belt (Ferrari et al., 2018). pects of this peculiar geologic province. Ignimbrites belonging to the two pulses already recognized 2. Methods in the SMO silicic large igneous province dominate the study region. In previous regional geologic maps of Mexico, silicic The geologic information has been mostly compiled from ignimbrites forming the Upper Volcanic Supergroup have been 1:250,000 and, when available, 1:50,000 scale maps of the Mex-

Page 2 Terra Digitalis Volume 2, Issue2

Table 1. Description of maps units (Tabla 1. Descripción de las unidades del mapa)

Map unit Age Description Late Cretaceous to Cenozoic continental magmatism and sedimentation

Unconsolidated surﬁcial deposits Quaternary Uppermost, recent alluvial and lacustrine deposits; mostly undergoing sedimentation.

Upper basaltic rocks Quaternary Basaltic lavaﬁeld and small cinder cones, mostly with intraplate afnity, of the Durango volcanicﬁeld

Bimodal volcanic rocks of the Pliocene to Quaternary Cinder cones and lavasﬂows, silicic lava domes and Trans-Mexican Volcanic Belt associated pyroclasticﬂows of the western Trans- Mexican Volcanic Belt

Siliciclastic rocks of Mesa Central Neogene Volcano-sedimentary sandstone, conglomerate and lacustrine depositsﬁlling endorheic basins of the Mesa Central. In most cases under active erosion.

Middle basaltic rocks Middle to late Miocene Fissure-fed maﬁc lavaﬂows and small shield vol- (14-9 Ma) canoes associated to extensional faults. Intraplate afnity in the central SMO (e.g., Río Chico-Otinapa graben) and subduction signature in the southern SMO and TMVB.

Siliciclastic rocks of the Late Oligocene to late Miocene Clastic and lacustrine depositsﬁlling the main tec- Sierra Madre Occidental tonic basins. Presently undergoing erosion.

Lower basaltic rocks Oligocene to early Miocene Fissure-fed maﬁc lavaﬂows capping or intercalated (32 to 19 Ma) in the ignimbrites of the SMO. Mostly showing an intraplate afnity.

Rhyolitic domes andﬂows Oligocene to early Miocene Rhyolitic domes capping the ignimbrites of each (29 to 18 Ma) pulse of the SMO.

Upper silicic ignimbrites Late Oligocene to early Miocene Large volume ash-ﬂow deposits of the second ign- (24 to 19 Ma) imbrite pulse of the SMO.

Lower silicic ignimbrites Late Eocene to Oligocene Large volume ash-ﬂow deposits of theﬁrst ignimbrite (43 to 29 Ma) pulse of the SMO.

Porphyritic intrusions Eocene-Oligocene (?) Hypabyssal intrusions of intermediate composition.

Andesitic rocks Paleocene (?) to Eocene Andesitic lavaﬂows associated to the Laramide Arc (Lower Volcanic Complex)

Basement terranes

Marine sedimentary successions Cretaceous Limestone, shale, and sandstone involved in folding (Sierra Madre Oriental) (Berriasian to Santonian) of Laramide age belonging to the Sierra Madre Ori- ental.

Marine sedimentary successions Late Jurassic Sandstone and shale involved in folding of Laramide (Sierra Madre Oriental) age belonging to the Sierra Madre Oriental.

Volcano-sedimentary and metasedimentary Triassic to Early Cretaceous Low to medium grade metamorphic succession of succession (Guerrero terrane) marine sandstone and shales, locally interbedded with volcanic rocks.

Page 3 Terra Digitalis Volume 2, Issue2 mapped as a single unit (e.g., Ortega-Gutiérrez et al., 1992; Ser- niego and Carlos González León for their constructive reviews vicio Geológico Méxicano, 2007). that helped to improve the work. In this work, we were able to separate the ignimbrite pack- ages of the twoflare-ups. We were also able to identify rhy- References olitic domes and porphyritic intrusive rocks associated with the ignimbritic pulses. In the study region rhyolitic domes were Bryan, S. E., Ferrari, L., 2013. Large igneous provinces and silicic large ig- emplaced at the end of thefirst ignimbriteflare-up often along neous provinces: Progress in our understanding over the last 25 years. GSA / major faults or intersection of faults. Bulletin 125 (7-8), 1053–1078, doi:10.1130 B30820.1. Bryan, S. E., Ferrari, L., Reiners, P. W., Allen, C. M., Petrone, C. M., Ramos- Although silicic rocks are volumetrically dominant, basaltic Rosique, A., Campbell, I. H., 2008. New Insights into Crustal Contributions volcanism is also widespread albeit with much lower volume. to Large-volume Rhyolite Generation in the Mid-Tertiary Sierra Madre Oc- Mafic volcanism occurred in two major pulses: thefirst span cidental Province, Mexico, Revealed by U–Pb Geochronology. Journal of Petrology 49 (1), 47–77, doi:10.1093/petrology/egm070. from late Oligocene to early Miocene with a peak in ages at 23- Calmus, T., Pallares, C., Maury, R. C., Aguillón-Robles, A., Bellon, H., Benoit, 22 Ma; the second is middle to late Miocene with peak at 13-11 M., Michaud, F., 2010. Volcanic Markers of the Post-Subduction Evolution Ma and is particularly voluminous in the southernmost part of of Baja California and Sonora, Mexico: Slab Tearing Versus Lithospheric the region, where this volcanism merges with that of the Trans- Rupture of the Gulf of California. Pure and Applied Geophysics 168 (8-9), 1303–1330, doi:10.1007/s00024-010-0204-z. Mexican Volcanic Belt. From a geochemical point of view, in- Castillo-Reynoso, J. C., 2018. Tectónica del límite sur de la Sierra Madre Occi- traplate basaltic lavas indicating sources in the asthenospheric dental: la zona de cizalla del Río Santiago. Universidad Nacional Autónoma mantle were emplaced mostly during thefirst pulse (Ferrari et de México, Posgrado en Ciencias de la Tierra, M.Sc. Thesis, 196 pp. al., 2017). The middle-late Miocene pulse mainly consists of Duque-Trujillo, J., Ferrari, L., Orozco-Esquivel, T., López-Martínez, M., Lons- dale, P., Bryan, S. E., Kluesner, J., Piñero-Lajas, D., Solari, L., 2015. basaltic andesite with higher Mg# at similar SiO2 contents and Timing of rifting in the southern Gulf of California and its conjugate mar- composition consistent with contributions from slab melt. In- gins: Insights from the plutonic record. GSA Bulletin 127 (5-6), 702–736, traplate magmatism, although scarce, also occurred during this doi:10.1130/B31008.1. pulse more inland, in the Rio Chico-Otinapa graben west of Ferrari, L., López-Martínez, M., Orozco-Esquivel, T., Bryan, S. E., Duque- Trujillo, J., Lonsdale, P., Solari, L., 2013. Late Oligocene to Middle Miocene Durango city. rifting and synextensional magmatism in the southwestern Sierra Madre Oc- The crosscutting relations between the main faults bounding cidental, Mexico: The beginning of the Gulf of California rift. Geosphere the graben and the volcanic units indicate that crustal extension 9 (5), 1161–1200, doi:10.1130/GES00925.1. was active since the late Oligocene but continued into the early Ferrari, L., Orozco-Esquivel, T., Bryan, S. E., López-Martínez, M., Silva- Fragoso, A., 2017. Cenozoic magmatism and extension in western Mexico: Miocene. The main graben structures can be grouped into a Linking the Sierra Madre Occidental silicic large igneous province and the southern structural domain with NNE-SSW to N-S orientation Comondú Group with the Gulf of California rift. Earth-Science Reviews and a northern domain with NNW-SSE orientation, with a limit 183, 115–152, doi:10.1016/j.earscirev.2017.04.006. Ferrari, L., Orozco-Esquivel, T., Navarro, M., López-Quiroz, P., Luna, L., approximately at the latitude of Durango city. There is also evi- 2018. Digital Geologic Cartography and Geochronologic Database of the dence of a late Miocene reactivation of extensional faults in the Trans-Mexican Volcanic Belt and Adjoining Areas. Terra Digitalis 2 (1), southern part of the Juchipila graben, where<10 Ma lacustrine doi:10.22201/igg.terradigitalis.2018.1.34. deposits are gently tilted. Small extensional fault scarps are Ferrari, L., Valencia-Moreno, M., Bryan, S., 2007. Magmatism and tectonics of the Sierra Madre Occidental and its relation with the evolution of the western also observed cutting lavaflows of the Durango volcanicfield, margin of North America, in Alaniz-Alvarez, S.A., Nieto-Samaniego, A.F. which indicate a Quaternary reactivation. In general, thermal (eds.). Geology of Mexico: Celebrating the Centenary of the Geological springs are spatially associated with normal faults (sometimes Society of Mexico: Geological Society of America, Special Paper 422, 1- buried) or with the contact between ignimbrites and grabenfill- 39. http://dx.doi.org/10.1130/2007.2422(01). Gastil, R. G., Phillips, R. P., Allison, E. C., 1975. Reconnaissance Geology of ing sediments. the State of Baja California. Geological Society of America Memoirs 140, No obvious caldera structure is observed in the region cov- 201 pp. doi:10.1130/MEM140-p1. ered by the map. Calderas forming the early ignimbrite succes- Genter, A., Goerke, X., Gra↵, J. J., Cuenot, N., Krall, G., Schindler, M., Ravier, sion may have been buried by subsequent eruptions. Webber et G., 2010. Current status of the EGS Soultz geothermal project (France). World Geothermal Congress, WGC2010, Bali, Indonesia, 25–29. al. (1994) proposed the existence of two calderas in the Juchi- Gerner, E. J., Holgate, F. L., 2010. OzTemp – Interpreted Tem- pila graben. However, ourfieldwork and new isotopic ages (to perature at 5km Depth Image. Geoscience Australia, Canberra, be published in a future paper), do not support this interpre- https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search?node=srv#/metad / tation but rather indicate that some of the youngest ignimbrites ata a05f7892-f9e7-7506-e044-00144fdd4fa6. González-León, C. M., Solari, L., Solé, J., Ducea, M. N., Lawton, T. F., Bernal, can be related tofissure parallel to major normal faults, as it has J. P., González-Becuar, E., Gray, F., López-Martínez, M., Lozano-Santacruz, been also proposed for the Bolaños graben (Ramos Rosique, R., 2011. Stratigraphy, geochronology, and geochemistry of the Laramide 2013). magmatic arc in north-central Sonora, Mexico. Geosphere 7 (6), 1392–1418, doi:10.1130/GES00679.1. Henry, C. D., Aranda-Gomez, J. J., 1992. The real southern Basin and Range: Acknowledgements Mid- to late Cenozoic extension in Mexico. Geology 20 (8), 701–704, doi:10.1130/0091-7613(1992)020<0701:TRSBAR>2.3.CO;2. Henry, C. D., McDowell, F. W., Silver, L. T., 2003. Geology and geochronol- The digital map was elaborated in the frame of grant UNAM- ogy of granitic batholithic complex, Sinaloa, México: Implications for PAPIIT IV100117 to Luca Ferrari. We thank Ángel Nieto Sama- Cordilleran magmatism and tectonics, in Johnson, S.E., Paterson, S.R., Fletcher, J.M., Girty, G.H., Kimbrough, D.L., Martín-Barajas, A. (eds.).

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Tectonic evolution of northwestern México and the southwestern USA: Ge- southern Sierra Madre Occidental, Mexico. Doctoral dissertation, Kingston ological Society of America Special Paper 374, doi:10.1130/0-8137-2374- University. 4.237. Servicio Geológico Mexicano (SGM), 2007. Carta Geo- Loza-Aguirre, I., Nieto-Samaniego, A. F., Alaniz-Álvarez, S. A., Iriondo, A., lógica de la República Mexicana, Scale 1:2,000,000. 2008. Relaciones estratigráfico-estructurales en la intersección del sistema https://mapserver.sgm.gob.mx/Cartas_Online/geologia/sgm2000.pdf. de fallas San Luis-Tepehuanes y el graben de Aguascalientes, México cen- Silva-Fragoso, A., 2015. Tectónica y volcanismo bimodal en la zona de transi- tral. Revista mexicana de ciencias geológicas 25 (3), 533–548. ción entre la Sierra Madre Occidental y la Faja Volcánica Trans-Mexicana al Loza-Aguirre, I., Nieto-Samaniego, A. F., Alaniz-Álvarez, S. A., Ortega- norte de Guadalajara, Jalisco. Universidad Nacional Autónoma de México, Obregón, C., 2012. Cenozoic volcanism and extension in northwestern Mesa Facultad de Ingeniería, Bachelor Thesis, 128 pp. Central, Durango, México. Boletín de la Sociedad Geológica Mexicana Siégel, C., Schrank, C. E., Bryan, S. E., Beardsmore, G. R., Purdy, 64 (2), 243–263. D. J., 2014. Heat-producing crust regulation of subsurface temper- Martínez-Reséndiz, V., 2016. Petrografía y geoquímica del vulcanismo máfico atures: A stochastic model re-evaluation of the geothermal poten- del Mioceno en la porción sur de la Sierra Madre Occidental. Universidad tial in southwestern Queensland, Australia. Geothermics 51, 182–200, Nacional Autónoma de México, Facultad de Ciencias, Bachelor Thesis, 160 doi:10.1016/j.geothermics.2014.01.005. pp. Torres-Rodríguez, V., Venegas-Salgado, S., Herrera-Franco, J., González- McDowell, F. W., Keizer, R. P., 1977. Timing of mid-Tertiary volcan- Partida, E., 1993. Manifestaciones Termales de la República Mexicana, in ism in the Sierra Madre Occidental between Durango City and Mazat- Torres-Rodríguez V. Geotermia en México. UNAM, Coordinación de la In- lan, Mexico. GSA Bulletin 88 (10), 1479–1487, doi:10.1130/0016- vestigación Científica, Programa Universitario de Energía, 1-79. ISBN: 968- 7606(1977)88<1479:TOMVIT>2.0.CO;2. 36-3444-3. McDowell, F. W., Roldán-Quintana, J., Connelly, J. N., 2001. Du- Webber, K. L., Fernández, L. A., Simmons, W. B., 1994. Geochemistry and ration of Late Cretaceous–early Tertiary magmatism in east-central mineralogy of the Eocene-Oligocene volcanic sequence, Southern Sierra Sonora, Mexico. GSA Bulletin 113 (4), 521–531, doi:10.1130/0016- Madre Occidental, Juchipila, Zacatecas, Mexico. Geofísica Internacional 7606(2001)113<0521:DOLCET>2.0.CO;2. 33 (1), 77–89. Ortega-Gutiérrez, F., Mitre-Salazar, L. M., Roldán-Quintana, J., Aranda- Gómez, J., Morán-Zenteno, D., Alaniz-Álvarez, S., Nieto-Samaniego, A., 1992. Carta Geológica de la República Mexicana escala 1:2,000,000. Uni- versidad Nacional Autónoma de México, Instituto de Geología, Mapa y This article accompanies the following material: / Texto Explicativo, 78 pp. HTML: DOI: 10.22201 igg.25940694.2018.2.53.106 Ramos-Rosique, A., 2013. Timing and evolution of late Oligocene to early Static map: DOI: 10.22201/igg.25940694.2018.2.53.107 Miocene magmatism and epithermal mineralization in the Bolanos Graben, Interactive map: DOI: 10.22201/igg.25940694.2018.2.53.108

Page 5 Geological map of the south-eastern part of the Sierra Madre Occidental Luca Ferrari, Juan Carlos Castillo-Reynoso, Teresa Orozco-Esquivel, Argelia Silva-Fragoso Centro de Geociencias, UNAM

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.! ^68.7 .! .! 74.340.5 .! ^ 30.8 ^ 43.5^^ ^ 35.8^36.8 37.1 ^ 36.8 ^ .! ^46.8 20.4 28.6 ^ ^28 ^31 27.9^^24.4 .! Legend ^29.2 .!

48.9 Unconsolidated surficial deposits ^^42.3 22°30'0"N (Quaternary) 22°30'0"N Upper basaltic rocks .! ^23.5 (Quaternary) ^27 Bimodal volcanic rocks of the Trans-Mexican ^21 Volcanic Belt (Pliocene to Quaternary) ^23.5 21.3 ^23 ^ Siliciclastic rocks of Mesa Central .! (Neogene)

.! Middle basaltic rocks 21.2 28 (Middle to late Miocene, 14-9 Ma) ^ ^ 22°0'0"N Siliciclastic rocks of Sierra Madre Occidental .! .!.! ! .! 22°0'0"N (Late Oligocene to late Miocene) . .!

.! Lower basaltic rocks ^47.2 24.324.5 19.9^ 40.6 ^^ ^ ^ ^ 25.3 21 25.321 ^ ^^^ 22.2 (Oligocene to early Miocene, 32 to 19 Ma) ^23.323.3 ^ .! .! 18.3 23.6^^^25.4 ^ .!.! ^ 25.2 29.3 .! 23.523.9 .! Rhyolitic domes and flows ^^^23.9 18.419.7 29.1 ^ 34.4 (Oligocene to early Miocene, 29 to 18 Ma) ^^ ^ .! .! .!.! .! Upper silicic ignimbrites 19.9^^ 26.2^^ ^^ 23.7 23.4 ^^ .! ^28.428.7 (Late Oligocene to early Miocene, 24 to 19 Ma) 48.1 .! ^ 7 21.3 ^ ^35 ^ Lower silicic ignimbrites 20.7 .!.! ^ ^26.6 6.5 (Late Eocene to Oligocene, 43 to 29 Ma) ^ .! 21°30'0"N 34.1 ^ 21.8 25.9 ^ 25.324.9 .! ^ Porphyritic intrusions ^^ .! .! .!.! 21°30'0"N (Eocene-Oligocene) 25.2 .! .! ^ 23.7 10.9 ^5.5 ^ *# ^ ^10.5 Andesitic lavas ^27.1 (Paleocene to Eocene) F ^5.6

21 11 ^ ^ .! Marine sedimentary successions ÿ ^11.5 *# ^23 .! (Sierra Madre Oriental) .! .! .! 22.923.8 .! ^^^22.9 *# .! (Cretaceous (Berriasian to Santonian)) .! *# .! *# .! *# *# 11 .! *# *# .! .! 30.1 10.2 ^*# .! *# *# ^ ^ *# .! Marine sedimentary successions *# *# *# .! *# F .! .! *#17.720 22.5 *# *# ^^ 2.8 ^ .! .! ^ 19.5 21.8 20.9 (Sierra Madre Oriental) .! ^ *# 26.6 ^.!.! ^ ^ *# *# # *# *# *# .! * 1.1 *# *# (Late Jurassic) ^ ^28 .!.! .! *# *# *# 3.33.23.8 *# 10.3 *# *# ^^ ^ 24.7 # *# *# *# *#*# ^ 20.2^ * *# ^10.2 21°0'0"N 22.719.3 *# *# ^ ^ 9.6 *# *# 1.8 26.7 ! .! *# ^^^^ 19.8 *# .! . ^^ 10.2 10 .! .! Volcano-sedimentary and metasedimentary Coordinate system ^ *# 23.6 10.1 .! 19.6 *# *# *# *# ^ .! .! 1.5 ^ ^ .! .! ^ 8.5*# .! .!.! Projection: Lambert Conformal Conic .! .! ^ *# 21°0'0"N succession (Guerrero terrane) 3.4 3.74 4.9 ^.! ^ *# ^ *# Datum: ITRF1992 3.5 *# .! 0 25^ 50 Km *# .! (Triassic to Early Cretaceous) *# 0.6 .!.! .! 1.1 Units: Grades 0.6 ^ .! *# ^ 4.7 0.9 © OpenStreetMap (and) contributors, CC-BY-SA ^ .!.! ^^^ *# ^ ^^^ *# 106°0'0"W 105°30'0"W 105°0'0"W 104°30'0"W 104°0'0"W 103°30'0"W 103°0'0"W 102°30'0"W