Field Guide to the Jurassic Otlaltepec and Tezoatlán Basins, Southern

P. 691‒709 VOL. 69NO. 3 BOL. SOC.GEOL.MEX.2017 04510, México. dad NacionalAutónoma deMéxico, CDMX, Posgrado Universi enCienciasdelaTierra, Mónica Ramírez-Calderón Mildred Zepeda-Martínez CDMX, 09230,México. Universidad NacionalAutónoma deMéxico, Facultad deEstudiosSuperiores Zaragoza, Diego E.Lozano-Carmona Patricia Velasco-de León México. nal Autónoma deMéxico, CDMX,04510, Instituto deGeología,Universidad Nacio [email protected] Michelangelo Martini Diego E. Michelangelo Oaxaca Mexico: sedimentologicalandpaleontologicalrecordsofPuebla Field guidetotheJurassicOtlaltepecandTezoatlánBasins,southern Manuscript June accepted: 15, 2017. Corrected manuscript received: June 10,2017. Manuscript received: December12,2016. Lozano-Carmona Martini , Patricia - , Mónica - Velasco-de León Jurassic flora Mexico, tinental rift basin,southern Keywords: Pangea breakup, intra-con es inMexico. assemblag quently, floral the diversification of variations inclimaticand conse conditions changes thatmajor topographic favored local Pangea could have produced fragmentation of lithosphericblocksduring the exhumation of to explore thehypothesisthat theprogressive this field trip, we will have the opportunity changes inclimatic conditions. Therefore, in clastic rocksmatch with es in provenance of logical data indicates that these major chang petrological and paleonto of integration The ed lithosphericblocksduring Pangea breakup. different fault-bound exhumation of result of Tezoatlán as the and areBasins interpreted and theOtlaltepec the Jurassicof successions Major provenance changes are recorded in to marine clastic deposits. alluvial-fluvial sist of exposed along two amazingcanyonsand con Mexico.aca, southern Observed outcropsare Puebla andOax are exposed inthe states of and TezoatlánOtlaltepec Jurassic Basinsthat the field trip will provideThis an overview of supercontinental mass. this equatorial margin the western of tion of recordstratigraphic related to the fragmenta during the Jurassic,sins representing a unique were successions ry accumulated into these ba Voluminous, continental to marine sedimenta bounded bysins exhuming basement highs. configuration characterized by ba subsiding faults. faults produced These a complex crustal to strike-slip major normal the development of Mexicodominated was by of tectonic history North and South America, the early Mesozoic along the emergent platebetween boundary position on Earth. Due to its paleogeographic was the most recent supercontinent assembled Pangea, which zation produced thebreakup of By early Mesozoic time, a major plate reorgani ABSTRACT Ramírez-Calderón . Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín , Mildred Zepeda-Martínez ------posición de particular interés, ya que seencontraba en el ocupaba una mexicano to tectónico global, el territorio reciente que se ensambló Durante este even en la Tierra. mentación de Pangea, lael supercontinente cual fue más la frag las placas tectónicas a escala global determinó A partir del inicio del Mesozoico, unareorganización de RESUMEN de México, flora delJurásico. gea, cuenca intra-continental,de rift sur Palabras clave: de Pan fragmentación versificación delaflora enMéxico. variaciones climáticas locales y, consecuentemente, la di favoreciendoreorganización sustancial enla topografía, rompimientouna de la Pangea pudo haber determinado ción de bloques litosféricos que acompañó el progresivo para explorar la hipótesis que elproceso de exhuma Por ende, seaprovecha la oportunidad de esta excursión con cambios importantes en las condiciones climáticas. cos indica que estos cambios la procedenciaen coinciden delos datos petrológicos y paleontológi La integración mayores rompimiento durante de Pangea. el progresivo ción de diferentes bloques de fallas litosféricos a lo largo han sido interpretados como el resultado de la exhuma de las rocas clásticas. Dichos cambios en la procedencia claras de cambios servan en la procedencia evidencias yTezoatlánjurásicas de las Cuencas deOtlaltepec pre clásticas aluviales-fluviales y marinas. Las sucesiones contienen afloramientos de sucesiones bien expuestos al sur de México. que se visitarán Las dos barrancas los estados en de Pueblales están expuestas y Oaxaca, y Tezoatlán,cuencas jurásicas de Otlaltepec las cua Durante esta excursión, los participantes visitarán las occidental-ecuatorial. dela Pangeaúnico dela fragmentación en sumargen marinas, estratigráfico las cuales representan unregistro de potentes sucesiones continentales a sitios de depósito tectónico fueronlas cuencas generadas los por este evento Durantealtos de basamento exhumación. en elJurásico, zada por numerosas cuencas subsidentes bordeadas por minaron unaconfiguración cortical compleja y caracteri y laterales,por la actividad de fallas quedeter normales México durante el Mesozoico temprano fue controlada geológica de la evolución dicha posición paleogeográfica, límite de placa entre Norte y Sur América. Debido a , /2017 691 ------

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico ABSTRACT INTRODUCTION / THE OTLALTEPEC Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico BASIN 692 692 1. Introduction rgetto fthe supercontinental mass during fragmentation of equatorial Pangea. progressive The margin of ern present-dayMexico were located along the west and Paleozoic rocksthat makeupthe backbone of Mesozoic time, Precambrian By the beginningof by the authors of this field guide. This is with the with is This guide. field this of authors the by paleontological results obtained in the last decade and petrological the synthesize to trip field this of occasion the take We flora. fossil and data logic conditions, by asit is suggested sandstonepetro atlán matchBasins withmajorchanges inclimatic compositional changes and Tezo in the Otlaltepec Pangea ( lithospheric blocksduring thefragmentation of different of exhumation of result the as terpreted major changesthat incomposition have been in which show deposits, clastic marine to al-fluvial alluvi exposed along two canyonsof and consist Mexico (Figure observed 1). The ern outcrops are Puebla and Oaxaca, south cated in the states of andTezoatlánthe Otlaltepec thatBasins are lo andfossiliferousrassic stratigraphic records of the Ju of overview an provide will trip field This floralassemblages. the diversification of es in climatic conditions inMexico and, therefore, during Pangea breakup mayhave favored chang fault-bounded lithospheric blocks exhumation of progressive the configuration, topographic the by influenced strongly is area geographic certain a Considering that the atmospheric circulation in 2016). 2013; Martini and Ortega-Gutiérrez, Goldhammer, 1999;Campos-Madrigal by basement (Morán-Zenteno highs extensionalbounded totranstensional basins uration characterized by progressively subsiding, config crustal complex a producing Mexico, of the topography shaped Jurassic significantly faults Lawton, 2001;Pindell and Kennan, 2009).These dell, 1985; Rossand Scotese, and 1988;Dickinson North America-South America divergence (Pin ed the NW –SEregional extension imposedby lateral, lithospheric-scale faults that accommodat to normal this time produced the development of / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín e.g. Martini et al ., 2016). The documented ., 2016).The et al ., 1993; et al ., ------/2017 2. TheOtlaltepecBasin Paleozoic Totoltepec pluton(Kirsch the upper the is faulted clastic succession against To succession. clastic sedimentary the south-west, a more than 2000 mthick of and iscomposed Tomás 2a) Santo and 1 (figures Otlaltepec of ings Basin isexposed Otlaltepec inthe surroundThe tive for future investigations. perspec some offering and Mexico of evolution on the climatic configuration and the paleofloristic Pangea exerted control that the fragmentation of stimulating aconstructiveon the discussion aim of ersn oeta 0%i oueo the Ot represent more than80% involume of Formations.Hueca andOtlaltepec units These Piedra the on focus will we trip field this During nteno event al-scale transgression (Figure 2b;Morán-Ze Formation, which were duringaregion deposited the Coyotepec ceous shallow-marine limestones of overlainis clastic succession This byLower Creta (Ramos-Leal, 1989; Morán-Zenteno flora Jurassic contain which of some deposits, ral litto to fluvial of composed are and conformities units are separated by regional-scale angular un nteno (Figure 2b; Ortega-Guerrero, 1989; Morán-Ze and Magdalena FormationsHueca, Otlaltepec, base tothe top, are: the Tianguistengo, Piedra has been subdivided into four units that, from the Basin the Otlaltepec recordthe stratigraphic of part, ly explored and studied. Along itssouthern part has been exhaustivepresent only itssouthern theentirepoorlyis basin known because at of framework architecturestratigraphic andinternal the basin are not exposed. comprehensive The of boundaries andeastern rez, northern 1978). The the Acatlán Complex (Figure 2a;Ortega-Gutiér juxtaposed toPaleozoicrocks metasedimentary of fault along whichis the clasticsuccession normal represented Basinis laltepec bya NNE-trending theOt of boundary fault (Figure western 2a).The along the W-trending, Matanza sinistralnormal et al et al ., 1993). ., 1993;Verde-Ramírez, 2016).These et al et al ., 1993). ., 2012) ------Figure 1 successions (modified fromsuccessions Martini boundaries ofand major metamorphic plutonic basementcomplexes,aswell asthedistributionof theJurassicsedimentary

Geologic map of thesouthern Geologic Puebla and southern northern Oaxacastates, Mexico,showing thelocationand tectonic

800' 18 N ° 730' 17 N °

pe aezi Totoltepec pluton Upper Paleozoic Grenvillian-age metamorphicrocks oftheOaxacanComplex Upper PaleozoicMatzitziFormation Lower-Middle Jurassic,dominantlysiliciclasticsuccessions Upper Jurassic-LowerCretaceouscarbonatesuccessions Undifferentiated UpperCretaceous-Cenozoic successions aezi eaopi ok fteAcatlánComplex Paleozoic metamorphicrocksof the aezi eaopi ok fteAyú Complex Paleozoic metamorphicrocksof the MEXICO USA et al A y u ., 2016). q u A T i c l e a a Río Saladofault z B t l o á a a n s t 800'W 98 800'W 98 l i á n ° ° n B a s i Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín n Rosario Nuevo A O T H y e t ú u T z l a a o Santo Tomás l l j a a u t Otlaltepec e x t a l p i á p a e n a c c n o B B a a s s i n i n Major lateralfault Inferred normalfault Major normalfault 0 730'W 97 730'W 97 ° ° N km 20

/2017

730' 17 800' 18 30' 18 N ° N ° N ° 693 693

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE OTLALTEPEC BASIN Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE OTLALTEPEC BASIN 694 694 2.1. PIEDRAHUECAFORMATION Zenteno column representativeSchematic litostratigraphic of thesouthernof theOtlaltepecBasin.Thecolumn partisaccording toMorán- will bevisitedduringThe locationofthethreemainoutcrops(yellowstars)that day ofthetripisreportedinmap.(b) thefirst its contact relationship withbasementrocksof theAcatlánComplexand contact Totoltepecpluton(modifiedits from Martini Figure 2 754'W 97 754'W 97 18 16'° N 18 20'° N ° ° lithofacies are interpreted as gravellithofacies are interpreted deposited bars Gp and Gt drainage. fluvial the of energy the in ing-upwardrecords successions cyclical variations tini (Figureupward 3;Mar intolithofaciesSr and Fl and Sp(Table 1;Miall,2006),eventually grading lithofaciesGt, Gp, St, from the base to the top of fin composed are that decameter-thick, successions fluvial ing-upward to meter- superposed, of Piedra Hueca FormationThe consists dominantly during Pangea breakup (Martini lithosphericblocks extension andexhumation of the complex of history ed as a manifestation of sandstone compositionthat has been interpret in change significant a display and Basin laltepec / Totoltepec pluton 0 Jurassic continentalsuccessions Cretaceous marinesuccessions Quaternary deposits Hueca, Otlaltepec,andMagdalenaFormations) Normal fault (a) Schematic geologic mapoftheOtlaltepecBasin,showing (a)Schematic thedistributionof theJurassic continentalsuccessionand et al Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Measured stratigraphiccolumnofFigure3 et al N km . (1993)and Verde-Ramírez(2016). , 06. h sproiin f tee fin these of superposition The 2016). ., 2

T Lateral fault L A L Acatlán Complex T E P E

C (Coyotepec Formation) (Tianguistengo, Piedra Matanza fault

et al B

A Detachment fault S ., 2016). I N a Santa CruzNuevo - - - - /2017 Stop 1 Stop 2 Stop 3 ee-hc escmoe ftabular-shaped, meter-thickof bedscomposed ( flows debris high-strength by formed were they thesemassive conglomerates, that suggesting of non-erosionalglomerates. base is typical Asharp (Figure 4c) are interbedded with cross-bedded con lithofaciesGci inversely-graded conglomerates of Locally, matrix- to clast-supported, poorly-sorted, represented (Martini by lithofacies Fl suspendedload culminating of with the deposition flow,fluvial the of energy in decrease progressive as the recordand Sr lithofacies are interpreted of ni unstable and laterally channels migrating (Marti dominated setting by depositional a reflecting 4a), laterally and vertically into each other (Figure shape conglomeratic bodies. Bothlithofaciescut scoop- during high-water stages,of andconsist e.g et al . Miall, 2006). Additionally, centimeter- to deci 746'W 97 Santo Domingo 746'W 97 Tiaguistengo ° ., 2016). The overlaying., 2016). The St, Sp (Figure 4b), ° Santo Tomas

Otlaltepec

820' 18 N ° 816' 18 N ° Totoltepec Conglomerate Sandstone Paleosol Angular unconformity pluton b et al Complex Acatlán ., 2016). Tianguistengo et al Formation Otlaltepec Formation Magdalena Coyotepec Formation Formation Lutite Formation Hueca Piedra ., 2016). - - - Creek (modified from Martini Hueca and OtlaltepecFormationsexposed along theMagdalena Figure 3 see Table1. description ofthe differentcompose thecolumn lithofacies that Piedra Hueca Formation Otlaltepec Formation 20 30 40 50 60 70 80 90 10 m 0 Representative stratigraphiccolumn ofthePiedra

S m c

C m c S S S t t o t o o et al p p p 2 3 EXPLANATION 1 ., 2016).Foradetailed Angular unconformity stratigraphic record Unexposed partofthe Paleosol Lithofacies Fl Lithofacies Sr Lithofacies Sp Lithofacies St Lithofacies Gci Lithofacies Gt C: conglomerate S: sandstone L: lutite c: coarse m: medium f: fine c: conglomeratic c: coarse m: medium f: fine Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín 2.2. OTLALTEPEC FORMATION suggests thatsuggests Mesoproterozoic-Neoproterozoic, con geochronology, chemistry anddetrital garnet detailed sandstone petrography, U-Pb detrital zir quartzo-feldspathic of (Figure integration 5). The in compositionfromvary feldspatho-quartzose to Sandstones from the Piedra Hueca Formation 2016). alluvial fan or braided fluvial system (Martini a proximalas been interpreted has tointermediate environments, tary the Piedra HuecaFormation withpresent-dayBased on the analogy sedimen ( flash-flood-deposits as terpreted with cross-beddedternated lithofaciesandare in lamination (lithofacies Sh; Figure 4d) are locally al laterally continuouswith upper-planesandstones an overbank environment that was intermittently Formationthe Otlaltepec as been has interpreted al., 2016). Based on these lithofacies assemblage, a subaerial in environment (Figure 3;Martiniet non-deposition oped during prolonged periods of devel andpaleosols (Fl), lutite laminated finely currents (lithofacies Gt, St, Sp, Sr in Table 1), emplaced by sandstone deposits grained traction fine- to conglomerate alternating rhythmically of Formationure Otlaltepec 6).The composed is the Piedra Hueca Formationunconformity (Fig Formation Otlaltepec The overliesangular in das, 2013). Mexico(Perrilliat andCastañeda-Posa of deposits JurassicMiddle fluvial and Lower in ubiquitous is served cycad leaves such as Morán-Zenteno Fossilsin the Piedra Hueca Formation are scarce. mented (Martini Mexico duringPangeaern breakup are alsodocu volcanic rocksthat were locally emplaced in east the Totoltepec pluton,andLower Jurassicsyn-rift Acatlán Complex, upper Paleozoic of granitoids the from Paleozoic rocks metasedimentary of ni detritus for the Piedra Hueca Formation (Marti can Complex (Figure 1) were the main source of the Oaxa rocks of metamorphic granulite-facies et al ., 2016).Subordinate detrital contributions et al et al ., 2016). . (1993)reported poorlypre Otozamites e.g /2017 . Miall, 2006). ssp., which et al 695 695 ., ------

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE OTLALTEPEC BASIN Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE OTLALTEPEC BASIN 696 696 sandstone representative of deposits lithofaciesSh,whichshows upper-regime planelamination. cross bedding; inversely-graded, (c) poorly-sortedconglomerate interpreted aslithofaciesGci;(d)tabular-shaped, coarse-grained shaped conglomerates of theGplithofacies; (b) coarse-and medium-grained of sandstone lithofacies deposits Sp,displaying planar Figure 4 ly derived from Mesoproterozoic-Neoproterozoic that Formationsuggest the Otlaltepec wasmost chemistry geochronology anddetrital garnet data with U-Pb detrital zircon integrated graphic zoarenites (Figure 5; Martini fromcomposition feldspatho-quartzose toquart Sandstones from Formationthe Otlaltepec in vary (Martini paleosols pedogenesis and the development of ial exposition duringlow-water periods, favoring flooded during high-water stages and with subaer / Photographs showing detailsofconglomerateandcompose thePiedra sandstone HuecaFormation:(a)scoop- that deposits Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín et al ., 2016). et al ., 2016). Petro - - - - /2017 imentary rocks of the Otlaltepec Formation the Otlaltepec con rocks imentary of which fossilsare scarce and poorly preserved, sed In contrast to the Piedra Hueca Formation in documented (Martini Mexico during Pangeaeastern breakup were also and Jurassicsyn-rift volcanic rocksemplaced in the Acatlán Complex rocksmetasedimentary of ordinate detrital contributions from Paleozoic pec pluton(Figure 1;Martini the Totoltewell as upper Paleozoic of granitoids the Oaxacan Complex as rocks of metamorphic et al ., 2016). et al ., 2016).Sub - - - - 2.3. TECTONIC IMPLICATIONS (modified from Martini composition of thePiedraHuecaand OtlaltepecFormation Figure 5 Otlaltepec Formations of thePiedracolumn Huecaand representative compose thestratigraphic Table 1.Synthesisofthelithofacies(Miall,2006)that F 10 Lithofacies code h rpryo oil companies ( the property of which are erationsand geophysical data, most of regional-scale geometrical consid of on the basis Pangea has been reconstructed in Mexico mostly last decades, the progressive fragmentation of reconstructing Pangea breakup. However, inthe South America, Mexico represents a key area for the nascent platebetween boundary North and positionalong its paleogeographic Because of leaves (Cruz-Cruz,2012). and cycads fern molds, and minor amounts of Bennettitales, trunk tain abundant fossilleaves of Gci Sp Gt Sr St Fl QtFL (Garzanti,2016)diagramshowing thesandstones

QF 50 Very fine-tocoarse-grainedsandstonedisplayingripplecros QF: Quartzo-feldspathic FQ: Feldspatho-quartzose Q: Quartzoarenite 090 90 Horizontally interlaminatedmudstone,siltstone,andveryfin

FQ have sharpbutnon-erosionalrelationshipwithunderlyingdepos Fine-to coarse-grainedsandstonedisplayingplanarcross-beddin et al Clast- tomatrix-supported,poorly-sorted,conglomerateshow Qt Q Scoop-shaped bodiesoftrough-cross-beddedconglomerate Fine- toverycoarse-grainedsandstonedisplayingtrough sandstone sandstone typically cutintoeachotherbothlaterallyandvertically. ., 2016). Otlaltepec Formation Piedra HuecaFormation inverse grading.Bedsofthislithofacies cross-bedding. e.g. Description sandstone. Pindell, 1985; L Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín - s-lamination. e-grained ing its. g. to document major displacements along Jurassic 2009). To date,have few authors only been able Rossand Scotese, 1988;Pindell and Kennan, faults in Mexico ( sozoic time in order to avoid the overlap between Me its present-day positionby the beginning of Mexico waslocated to the north-westsouthern of plate tectonic reconstructions, which predict that ing faults. withregional-scaleagreement in is This by major sinistral block motionsalong W-trend Pangea Mexico isexpressed breakup in southern ures 1and2).According the interpretation, tothis (fig south the to Basin Otlaltepec the thatbounds which isa W-trending, structure sinistral normal thisintrusive body along the Matanza fault, of rapid exhumation as the result of been interpreted Totoltepec Formationthe Otlaltepec plutonin has sudden enrichment indetritus coming from the different crustal blocks. the More detail, in of tion progressive continental attenuation andexhuma the a manifestation Basinis the Otlaltepec of of provenance documented in the Jurassic succession to Martini clasticrocks. Infact,according of enance analysis can be indirectly recognized using a detailed prov Jurassic faults that participated to Pangea breakup the Otlaltepec Basin offers agreat how example of time.rassic record stratigraphic The exposed in majordisplacements duringJu anyevidence of fault reactivation that, inmostcases, obliterated tectonic events produced multiple of episodes Late Cretaceous andPaleocene overprinting of Martiny et al Channe et al Deposit formedunderlowerplanebedregime ., 2012). This is mostly due tothe mostly is ., 2012).This High-strength, plasticdebris-flow-deposit Sinu . (2016), the change in sandstone Transverse andlinguoid(2D)dune l fillassociatedtolow-sinuosity,braided ous-crested andlinguoid(3D)dune Ripples (lowerflowregime) e.g . Alaniz-Alvarez Interpretation dra inages /2017 et al ., 1996; 697 697 ------

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE OTLALTEPEC BASIN THE OTLALTEPEC BASIN / THE Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico TEZOATLÁN BASIN 698 698 2.4. PALEOCLIMATIC IMPLICATIONS Figure 6 ihteehmto fthe Totoltepec pluton. with the exhumation of (2016), the increase in quartz content coincides reconstruction proposedgraphic by Martini van der Kamp, 2010).Adoptingthe tectono-strati under humid climatic conditions ( feldspar dilution bysuming chemical weathering FormationOtlaltepec canbe explained only as strong quartz enrichmentfrom insandstones the thisconsideration, the In lightsof ic composition. sourced by rocksthat displaya quartzo-feldspath FormationsPiedra Hueca and Otlaltepec were and plutonic assemblages,metamorphic both the of combinations different from derived were they FormationOtlaltepec (Figure 5). In fact, although (up to 98 %)inmostsandstone samplesfrom the cannot explain the dramatic enrichment inquartz ological assemblages. However, thisprocessalone different lith different of composed crustal blocks exhumation and subsequent erosion of result of as the Basin canbe interpreted the Otlaltepec of change record documented in the stratigraphic As noted by Martini Pangea ( North and South America in the reconstruction of / Exposure oftheangular unconformityparticipants willobserve betweenthePiedra that Huecaand OtlaltepecFormations. Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín e.g . PindellandKennan, 2009). et al . (2016), the provenance e.g . Basu,1985; et al - - - - /2017 . Otlaltepec Formation 3. TheTezoatlánBasin whereas the southern limit with thecoeval whereas Tlaxia thesouthern aries are buried under Cenozoic volcanic rocks, tiny displacementsduringJurassicnormal time (Mar activated structure that produced major sinistral fault (Figure 1),whicha kilometer-scale, is multi-re representedis bythe WNW-trending RíoSalado theTezoatlán Basin of boundary northern The Oaxaca (Figures 1 and 7a). León in the state of Huajuapande the homonymous town, southof TezoatlánThe located Basinis of in the vicinity sions were deposited. matic conditionsunder which the Jurassic succes cli future studiesfocused onthe reconstruction of the Otlaltepec Basin offers someof perspective for explored and, therefore, record the stratigraphic present, this hypothesis hasnot been exhaustively sediments. At that controlledof the composition fragmentation, producing local climatic variations ton could have favored the progressive landscape the Totoltepec plu tonic exhumation and uplift of Therefore, that wethe possibility suggest the tec et al ., 2012). The eastern and western bound and western eastern ., 2012). The Piedra HuecaFormation ------Morán-Zenteno columnmap. (b)Schematiclithostratigraphic representative of theTezoatlán Basin.The column isaccording toErben (1956)and et al Figure 7 17 31'N° 17 34'N° 17 37'N° ., 1993). The location of the main outcrops (yellow stars) that will bevisitedduring., 1993).Thelocationofthemain outcrops(yellowstars)that thesecond dayofthetripisreported inthe (a) Schematic geologic mapoftheTezoatlán Basin,showing (a)Schematic thedistributionof theJurassic (modified from Morán-Zenteno Yucuquimi during theseconddayoftrip Stratigraphic columnthatwillbeobserved Lower JurassicDiquiyúFormation Lower JurassicRosarioFormation Lower-Middle JurassicCualacFormation Tecocoyunca Group Middle Jurassic Upper Jurassic-LowerCretaceousmarinelimestone Cenozoic rocks Normal fault 753'W 97 et al ° Yucuñuti . (1993). Rosario Nuevo S a t o S p San Juan t 9 S o Diquiyú p t o 4 p 5 Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín 750'W 97 ° S t S o S t p o 0 t 8 o p p 6 7 N km 2 Conglomerate Coal Calcareous shale Sandstone Lutite b /2017 shallo-marine continental littoral to Formation Formation Formation Upper Lower Rosario Diquiyú part part Cualac

699 699 Tecocoyunca Group Tecocoyunca

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE TEZOATLÁN BASIN Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE TEZOATLÁN BASIN 700 700 overlies Lower Jurassic, mafic to felsitic volca felsitic to mafic Jurassic, Lower overlies et al Morán-Zenteno 1956; (Erben, flora Jurassicfossil thattinental clastic succession abundant contains anapproximately 1000 mthickcon composed of forAs Basin,the Tezoatlán the Otlaltepec Basin is co Basin(Figure 1) has not been studied in detail. lán and Otlaltepec Basins.lán andOtlaltepec the Tezoatand paleoenvironmental evolution of posited and compare the tectono-stratigraphic under whichwas de succession the sedimentary the tectonic discuss setting and climatic conditions tic unitsexposed inthe Tezoatlán Basin. We will the three clas cal andpaleontological aspects of sedimentologi different observe to opportunity have the will participants trip, field this During 1956). and the TecocoyuncaGroup (Figure 7b;Erben, to the top, are: the Rosario andCualac Formation ed into three units that, stratigraphic from the base exposed inthe Tezoatlán Basin hasbeen subdivid Olóriz val and Westernmann, 1986; Olóriz theTethys( with faunalassemblages of gested byof the severalaffinity Jurassic ammonites Mexico andAtlantic Ocean, as it is sug of Gulf the in spreading sea-floor by driven transgression a idea of contrasts with the most widelyaccepted time (Cantú-Chapa, 1998). However, thisscenario Mesozoic during waters marine Pacific by north ico wasprogressively from transgressed southto these data,proposed some authors that Mex of Westermann,1986; Cantú-Chapa, light 1998). In fossilnian fauna (Erben,1956;Sandoval and by marine rocksthat contain a Bajocian–Batho tal in the succession Tezoatlán Basinisoverlain posits are Early Cretaceous in age, the continen Basin,inwhichOtlaltepec theoldest marine de the from Differing 2016). Ortega-Gutiérrez, and Pangea (Martini that accompaniedthe breakup of the syn-riftmagmatism ed as amanifestation of Durán-Aguilar, 2013), which have been interpret the Diquiyú Formation (Figure 7b; nic rocksof / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín ., 1993). This clastic succession conformably conformably clasticsuccession ., 1993).This et al ., 2003). The Jurassic., 2003).The clastic succession et al e.g . Sando ., 2000; ------/2017 3.1. ROSARIO FORMATION plain environment (Morán-Zenteno flood associated its and stream fluvial high-energy a sario Formation record asthe stratigraphic of acteristics, the Rointerpreted diverse authors 8a; Durán-Aguilar,these char 2013).Basedon cation, imbrication, andinverse (Figure grading stratifi crude display locally and poorly-sorted, ateare matrix-supported,deposits dominantly et al lutite, andcoal(Erben, 1956; Morán-Zenteno conglomerate and minor sandstonelenses, of RosarioThe Formation is dominantlycomposed the floral content content recoveredfloral the from the Rosario For lasco-de León, 2016).Representative samples of and Ve the Ginkgoalesorder (Lozano-Carmona includes the Tezoatlán area in the distribution of the as an 8m-long fossiltrunk that has been determined and Velasco-detion, Ortega León (2015) collected Kingdom andRajmahall Hills inIndia.Inaddi ilar to those reported in Yorkshire in the United Williamsoniaceae are sim reproductive organs of the whereas Gondwana, with affinity an suggests Person,1975; Person, 1976). Genus (Delevoryas, 1966,1968,1969;Delevoryas and as thenewgenus Bennettitales (Williamsoniaceae), as well of gans male and female reproductive or a newspeciesof documented in the Rosarioous authors Formation during thelastdecades. thors Moredetail, in previ au different by studies several of object been has Rosario Formation the flora, fossil its of Because the Rosario Formation out. hasnotbeencarried 1993). However, a detailed provenance studyof lying DiquiyúFormation (Morán-Zenteno to bederivedbeen interpreted from the under volcanic(Figureclasts 8b)that have of composed the Rosario Formation are mostly of stone deposits Durán-Aguilar, 2013).Conglomerate and sand Agathoxylon Nehvizdyella ., 1993;Durán-Aguilar 2013). Conglomer Harting. Moreover, the finding of finding the Moreover, Harting. včk Flo-ag t Dasková et Falcon-Lang Kvaček, Mexiglossa Delevoryas et al Mexiglossa Mexiglossa et ., 1993; Person et al ., ------3.2. CUALAC FORMATION sorted conglomerateshowing crude inaconglomeratic bedding;deposit.clasts (b)imbricatedvolcanic Figure 8 a tion in a transitional contact. The CualacFormaa transitional tion incontact. The Cualac FormationThe overlies the Rosario Forma the fieldtrip. Rosario Nuevo duringthedaysecond of um of mation willbe observed at the Geological Muse ftheseclasticrocks has notbeenpublished. of 2013). To date, anexhaustive provenance analysis 9b; Morán-Zenteno rocks quartz andquartz-rich(Figure metamorphic fragments of Formation is dominantly made up of volcanic clasts, the Cualac mostly composedof from theunderlying Rosario Formation, which is Differing interpretations. competing two these on discussion exhaustive an permit will trip field the (Durán-Aguilar, 2013).Exposures observed during a meandering river recordthe stratigraphic of that suggested this unit representsas other authors region (Morán-Zenteno relief developed alluvial fans a high in proximal part of the Cualac Formation interpreted authors asthe out. Some not been carried thisunithas studyof Durán-Aguilar, 2013). A detailed sedimentological ure 9a; Erben, 1956; Morán-Zenteno (Fig lutite and sandstones fine-grained to coarse- conglomeratic sandstoneinterbedded with minor conglomerate and tion isdominantlycomposedof Photographs showing detailsofconglomeratic ofdeposits tomatrix-supported, theRosarioFormation: (a)clast- poorly- et al ., 1993;Durán-Aguilar, et al ., 1993),where et al ., 1993; Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín - - - - - 3.3. TECOCOYUNCA GROUP b and coal containing abundant fossil flora (Figure flora fossil abundant containing coal and sandstone, black shale, dominantly composedof the TecocoyuncaGroup is part of stratigraphic and may be subjective. the lower Ingeneral terms, easy not is field the on units these of recognition are often subtle and, therefore,formations the these between differences sedimentological and by Morán-Zenteno et al. (1993), the lithological Yucuñuti Formations. However,pointed out as are: the Zorrillo, Taberna, Simon, Otatera, and that formations different five into subdivided be to Erben (1956), the TecocoyuncaGroup can Formation in a transitional contact. According TecocoyuncaThe Group overlies the Cualac this genus from differentiate to permit characteristics These 10b). in rowsarranged with apparent disorder (Figure play slightlywavywalls, stomas, sunken andare the Tezoatlán area are rectangular shape,in dis cellsof epidermal León, 2014). A detailed cuticle showsanalysis that Velasco-de and (Guzmán flowers liamsoniaceae zamites well10a), as as Tezoatlánof consists Basin Fossil flora in the Cualac Formation exposed in the , Otozamites hespera Zamites oaxacenis Glossopteris Mexiglossa Mexiglossa varia , Ptillophyllum Brongniart. Mexiglossa Mexiglossa varia , Z. diquiyui recovered from /2017 sp. andWil , (Figure Anomo 701 701 - - -

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE TEZOATLÁN BASIN Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico THE TEZOATLÁN BASIN 702 702 subangularrocks. derived fromquartz-richmetamorphic clasts showingmeter-thick successions atypical fining-upward trend; (b)clast-supported, poorly-sortedconglomeratecomposed of Figure 9 Photomicrography ofleafcuticle Figure 10 a Tecocoyunca Group as a hasbeen interpreted the ontological characteristics,of the succession 1998). Based on the sedimentological and pale Sandoval andWestermann,1986; Cantú-Chapa, man, and as BajocianandBathonian age such ammonites of and sandstoneandshalewithmarinemollusks of part composed is hand, the upper stratigraphic 11; Morán-Zenteno / Photographs showing detailsofconglomerate, sandstone,Formation:(a)superposedcompose theCualac and lutitethat Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín (a)Leafof Duashnoceras Parastrenoceras Mexiglossa varia Westermann, et al Ochoterena (Erben, 1956; Mexiglossa varia ., 1993).Onthe other in finely laminated lutite of the Cualac Formation. Arrows pointtobaseandof theCualac infinely apexof laminatedlutite theleaf. (b) Leptosphinctes . Buck - - /2017 b available. presentlyis thesesandstones not of nance analysis (Durán-Aguilar, 2013). However, a detailed prove fragments quartz and quartz-rich metamorphic Tecocoyunca Group are mainly composed of the forAs the Cualac Formation,of sandstones (Morán-Zenteno ter marine environment connected to an open sea that progressively evolved intoalittoral to shallow-wa areas marsh with environment flood-plain et al ., 1993). - - 3.4. TECTONIC IMPLICATIONS of theTecocoyuncaGroup.part compose thelowerstratigraphic Figure 11 Ginkgoales, Caytoniales, Czekanowskiales, Podo from various pointed out the presence authors of icales, and Equisetales. Subsequently, new findings Bennettitales, Cycadales, Fil variousof specimens and Silva-Pineda (1984) originally documented eral authors. Wieland (1914), Delevoryas (1971), study by sev coyunca Group hasbeen object of the Teco in contained flora fossil abundant The exposed inthe Tezoatlán Basin couldbe the result Basin, the compositional change inthe succession for 2013). As it has been suggested the Otlaltepec (Morán-Zenteno fragments derived from basement acrystalline quartzandquartz-rich metamorphic of consists Formation and Tecocoyunca Group dominantly the Cualac Formation,Diquiyú of clasticdeposits clasts apparentlynic sourced bythe underlying volca sario Formation are mostly composedof theRo Whereas conglomerate of and sandstone atlán recordsBasin amajorcompositionalchange. the Jurassicexposedclastic succession inthe Tezo Basin, it As has been documented in the Otlaltepec 2013, 2014). and Velasco-de León 2014;Velasco-de León 2012;Lozano-Carmona 2010; Lozano-Carmona, the Tecocoyunca Group part (Rojas-Chávez,of zamitales, and Filicales in the lower stratigraphic Exposure ofcontinentalsandstone andthat lutite et al ., 1993; Durán-Aguilar, et al Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín ., ------4. Conclusions 3.5. PALEOCLIMATIC IMPLICATIONS fthe Acatlán Complex (Figure 1; Martiny of to Paleozoicquartz-rich rocks metasedimentary whichthe Tezoatlán directlyis Basin juxtaposed a major NNW-trending Jurassicstructure along is not presently possible. Río Salado fault is The the Tezoatlán Basin in the of clastic succession blocksand the consequent change incomposition basement faults that controlled the exhumation of not available.is Therefore, recognizingthe major ly, adetailed provenancefor analysis these units Pangea. Unfortunate during thefragmentation of blocks basement different of exhumation the of ment in quartz and quartz-rich metamorphic frag ment in quartz andquartz-rich metamorphic the possibility thatdiscuss the progressive enrich to occasion the take will we field, the On 2012). nooi aasget htdpsto fJurassic ontologic data that of suggests deposition sandstone petrologic andpale of integration The provenance changesuccession. inthe sedimentary climatic change seems to coincide with a major Jurassictime. Basin,suchin the Otlaltepec As a can bedocumented in the Tezoatlán area during erations, a major change in climatic conditions asco-de León by lower temperature and higher humidity (Vel underclimaticdeposited conditionscharacterized the Cualac Formation indicate that this unit was the presence of (Velasco-de León highrainfall with severe droughts andperiods of hightemperature associated periods of alternating posited under a seasonalclimate characterized by Rosario Formation that suggests de this unitwas extracted from the gymnosperms of specimens foliarThe areaconducted onvarious analysis along theRíoSaladofault. the Acatlán Complex rocksmetasedimentary of Group couldbeproduced bythe exhumation of ments inthe Cualac Formation andTecocoyunca et al Ceratozamia et al ., 2013).Based on these consid ., 2013).Onthe other hand, and Mexiglossa Mexiglossa varia /2017 et al 703 703 in ., ------

THE TEZOATLÁN BASIN / Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico CONCLUSIONS Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico CONCLUSIONS / FIELD TRIP 704 704 (18°16’59.92”N, 97°48’9.77”W) 5.1.1. STOP 1:PIEDRAHUECAFORMATION 5.1. DAY ONE 5. Fieldtrip oniewt ao hne npoeac fcoincide withmajorchanges inprovenance of variations climatic Interestingly, these flora. fossil ported bysandstone whole-rock and composition fromsup is conditions or seasonaltohumid dry climatic conditions. More in detail, an evolution accompanied bywas lán Basins major changes in andTezoatin the Otlaltepec clastic successions neeg fa in braided energy fluvialof system. Locally, deci blage is interpreted to reflect the seasonal decrease overlie lithofacies assem sandstone deposits. This Fl) (lithofacies lutite and sandstone fine-grained horizontally laminated,Locally, very drapes of trough- to planar-cross-bedding (lithofacies St, Sp). show that sandstone fine-grained to glomeratic- upwardfacies Gt and Gp) and grade into con dominantly trough- to planar-cross-bedded (litho Hueca Formation.are Conglomerate deposits the Piedra sandstone, andlutite representative of At thisoutcrop we willobserve conglomerate, Formations, as well astheirfossil flora. the Piedra Hueca and Otlaltepec acteristics of detail the sedimentological and petrological char in examining of possibility the canyonoffers This Basin along the Magdalena Canyon (Figure 3). the Otlaltepec observe will representative exposures of trip participants the of day first the During during Jurassic time. floral assemblages in Mexico the diversification of favored local variations inclimatic conditionsand reorganizationduced amajortopographic that Pangea pro that theprogressive fragmentation of these considerations,on we preliminarily suggest blocksthat accompanied Pangea breakup. Based lithospheric fault-bounded different of humation ex the complex of history the manifestation of pec andTezoatlán as are successions interpreted clastic rocks. Provenance changes inthe Otlalte / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín ------/2017 THE PIEDRAHUECAANDOTLALTEPEC FORMATIONS 5.1.2. STOP 2:ANGULAR UNCONFORMITYBETWEEN 97°48’12.49”W) 5.1.3. STOP 3:OTLALTEPEC FORMATION (18°17’2.90”N, (18°17’0.35”N, 97°48’9.73”W) provenance of this stratigraphic unit. thisstratigraphic provenance of outcrop inorder to stimulate on the the discussion and geochronologic data will bepresented at the Complex are also present. Detailed petrographic sourcedclasts bymetamorphic cies the Acatlán the Oaxacan Complex. Greenschist-fa rocksof zo-feldspathic clastsderived from granulite-facies quart are stone deposits dominantlycomposedof during flash-flood events. Conglomerate and sand facies, andthey to be emplaced are interpreted lamination with cross-bedded are alternated litho laterally continuouswith upper-planesandstones tabular-shaped, meter-thickof composed deposits abundant cycad leaves, andfern andpaleosols de Table 1), finely laminated lutite (lithofaciesFl) with bytraction currents (lithofacies Gt,St, Sp, Srin conglomerate to fine sandstone emplaced deposits rhythmically alternating which is composedof Formation, the Otlaltepec tativeof succession At thisstop, participants will observe a represen discussed at thisoutcrop. these faults will be observed and Some cession. of faults throughout the entire suc normal imentary centimeter- to meter-scale, syn-sed occurrence of Basin areaOtlaltepec is given by the widespread faulting in the syn-sedimentary tions. Evidence of the Totoltepec Forma pluton in the Otlaltepec ported bythe enrichment inclastsderived from sinistral Matanza fault. Suchsup is interpretation theTotoltepec plutonalongthenormal tion of exhuma as the result of isinterpreted conformity Formation.Otlaltepec aforementioned The un the tion are overlain by~20°-dipping strata of the Piedra Hueca Forma ~50°-dipping beds of where these two an angular unconformity is units between contact the field, the on observe will we Formations.the Piedra Hueca and Otlaltepec As relationship thestratigraphic between posure of thisstopisto observe an excellent ex goal of The ------97°50’54.39”W) 5.2.2. STOP 5:ROSARIO FORMATION (17°36’9.35”N, 97°50’56.97”W) 5.2.1. STOP 4:DIQUIYÚ FORMATION (17°36’6.78”N, 5.2. DAY TWO examiningdetail in the sedimentologic and petro of opportunity canyon the This offers 12). (Figure zoatlán Basin along the Rosario Nuevo Canyon the Tewill observe representative exposures of the trip, participants During the second day of van derKamp, 2010). under humid climatic conditions ( produceddilution was bychemical weathering in quartz is explained here assuming that feldspar total framework strong This enrichment grains). the a highenrichment inquartz (up to 98% of source rocks, Formation the Otlaltepec displays Despite the quartzo-feldespathicof composition Formation. theOtlaltepec the provenancecuss of will bepresented at thisoutcroporder in to dis and U-Pb geochronologic data on detrital zircons and OaxacanComplex. Detailed petrographic the Totoltepec pluton quartzo-feldspathic rocksof are and sandstonedeposits dominantlysourced by sition ina subaerial environment. Conglomerate non-depo veloped during prolonged periods of otycmoe fclast- to matrix-supported, of composed mostly the Rosario Formation. unit is This exposure of At this stop, participants will observe an excellent Formation. the Rosario volcanic rockswith volcanic clastsof the Diquiyú Formation in order to compare these is to observe textural and compositional details of nteno for the overlying Rosario Formation (Morán-Ze Diquiyú Formation as the source is interpreted the Tezoatlán The clastic succession. basement of the Diquiyú Formation that represents the rocksof At this stop, we will observe andesitic volcanic content. compose the Tezoatlán Basin, as well its fossil flora that units thestratigraphic logic characteristicsof et al ., 1993). Therefore, the aim of this stop this ., 1993).Therefore, theaimof e.g . Basu,1985; Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín - - - - - 97°50’40.9”W) 5.2.3. STOP 6:CUALAC FORMATION (17°36’18.2”N, (17°36’22”N, 97°50’38.8”W) 5.2.4. STOP 7:LOWER TECOCOYUNCA GROUP as through toplanar crossbedding, imbrication, structures sedimentary such display a variety of that shale and sandstone, fine-grained to coarse- conglomerate, Cualac Formation of iscomposed the Cualac Formation. Atthispoint,the posures of At thisoutcrop, we willobserve representative ex tional similaritieswiththeDiquiyúFormation. volcanic rocksthat show textural and composi in theRosario Formation areof mostly composed stream (Morán-Zenteno fluvial ahigh-energy recordas the stratigraphic thors of that deposits have by beeninterpreted previous au poorly-sorted, and crudely-bedded conglomerate no environment by as it was suggested Morán-Zente in a proximalthis unit was deposited alluvial fan Formation, we will evaluate the possibility that the Cualac the sedimentological characteristics of and ripple marks. After a careful observation of pressions that will be described on the field in order thisoutcrop preserves leaves im 1993). Shale of (Morán-Zenteno environment flood-plain a record as the stratigraphic been of interpreted sandstone, shale, and coalthat has of succession a cocoyunca Group, which iscomposed here of the Te the lower part of stratigraphic posures of thisstopisto observe excellent ex goal of The Anomozamites mined as leaves that have been deter serve impressionsof pre layers shale laminated finely outcrop, this At record.tic stratigraphic such a compositional change in the clas cance of signifi the field the on discuss Wefragments.will quartz and quartz-rich metamorphic posed of In fact, the Cualac Formation isdominantlycom in compositionrelative to the Rosario Formation. the Cualac Formation displaya dramatic change participants will observe that of clastic deposits proposed by Durán-Aguilar (2013). Furthermore, et al . (1993) or in a meanderingriver. (1993) orin it was as Mexiglossa Mexiglossa varia . , Zamites et al , /2017 Otozamites ., 1993). Clasts et al , and 705 705 ., ------

Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico FIELD TRIP FIELD TRIP / ACKNOWLEDGEMENTS Field guide to the Jurassic Otlaltepec and Tezoatlán Basins, southern Mexico / REFERENCES 706 706 ARCHEOLOGICAL SITE 5.2.7. STOP 10:CERRO DELASMINAS NUEVO (17°36’11.56”N, 97°51’13.7”W) 5.2.6. STOP 9:GEOLOGICAL MUSEUMOFROSARIO (17°36’29.6”N, 97°50’38.7”W) 5.2.5. STOP 8:UPPERTECOCOYUNCA GROUP, iinfo h oe oteuprprso the Tesition from the lower to the upper parts of At this outcrop, participant will observe the tran unit wasdeposited. the to climaticdiscuss conditions under which this the area during that time. Cerrothe is delasMinas settlements reservedand was for the elite of ber of that crossed thisregion. site contains a num The theabsolute controlthe trade on routespermitting the valley,strategic position overof the farmlands large Huajuapan de León. This hill was ina of locatedis Minas a hillthat in dominates thevalley Mexico.tihuacan inthe Valley Cerro delas of Oaxaca and Teo as Monte Alban inthe state of such flourished cities major other period, this of sic period between 400 and800CE. In the course and reached its climaxthroughout the early Clas and it was founded during the Preclassic period (Figure site belongs to the Ñuiñe culture, 2). This HuajuapandeLeón thatlocated is northward of thevisit archeological site “Cerro delasMinas” we willtakethe opportunity to timepermits, If the Tezoatlán Basinare exposed. fromsils of the continental to marinesuccession Rosario Nuevo, where representativeseum of fos We will take the to visit the occasion regional mu ophorella as bivalves andammonitessuch Bathonian fossils of and calcareous shale that contain Bajocian and rhythmically interbedded sandstone composed of in the Tezoatlán area. Shallow are marine deposits aregional marine transgression the resultwas of shallow-marine environment sedimentary that change froma gradual continental to littoral and cocoyuncaGroup. transition inmarked This by / Boletín de la Sociedad Geológica Mexicana Geológica Sociedad la de Boletín Oppelia , and , Leptosphinctes Vaugonhia . , Parastrenocera , Trigonia , My ------/2017 6. Acknowledgements 7. References that greatly improved thisfieldtrip. anonymousreviewers for their helpful comments León. We Franciscothank Vega Vera and two IN106010-3 to Patriciani and grants Velasco-de IA100214 andIA102216toMichelangelo Marti Investigación e Innovación Tecnológica) grants funded byPAPIIT (Programa deApoyo aProyectos projects de research different of result rect di the are guide trip field this in presented Data open tothepublic. the Mixteca Baja region archeologicalonly site of Cantú-Chapa, A., 1998, Las transgresiones Cantú-Chapa, A., 1998,Lastransgresiones E., Centeno-García,Campos-Madrigal, E., and relief climate of Influence 1985, A., Basu, Alaniz-Alvarez, S.A., van der Heyden, P., Nieto- Ciencias Geológicas, 15,25–37. jurásicas en México: Revista Mexicana de de CienciasGeológicas, 30,34–50. AyuquilaTecomazúchil: y RevistaMexicana León, Oaxaca:Revisión de lasformaciones el área de Texcalapa, Puebla-Huajuapan de de las sucesionesclásticasdel Jurásico Medioen tectónico significado y paleoambiental 2013, Sedimentología, reconstrucción Mendoza-Rosales, C.C., Silva-Romo, G., 148, 1–18. Series, Dordrecht, Netherlands, D. Reidel, arenites, NATO Advanced Study Institute areas, released sands at source on compositionof Mexico: Geology, 24,443–446. of the Gulf Mexico related to the opening of Middle Jurassic strike-slip faulting in southern Radiometric and kinematic evidence for Samaniego, A.F., F., Ortega-Gutiérrez, 1996, in uf, .. (d) Poeac of Provenance (ed.), G.G., Zuffa, - - Delevoryas, T., Person,C.P., 1975, Delevoryas, T., 1971,Bioticprovincesand Delevoryas, T., 1969,Glossopterid leaves from the Delevoryas, T., 1968,Jurassicpaleobotany in Delevoryas, T., 1966,Huntingfossilplants in estratigráfico Análisis 2012, M.A., Cruz-Cruz, Erben, H.K., 1956,El Jurásico Medio y el Durán-Aguilar, R.F., 2013,Sedimentología W.R.,Dickinson, Lawton, T.F., 2001, p. Autónoma deMéxico, Bachelor’sthesis, 109 UniversidadInstituto deGeofísica, Nacional Santa Cruz Nuevo, Puebla: México, D.F., Santo Tianguistengo,Domingo Oaxaca, de lasecuenciaJurásica delaregión de México, 140p. D.F., Monografía, Geológico Internacional, Calovianode México, de México, Master’s thesis, 87p. Geofísica, Universidad NacionalAutónoma y procedencia: México, D.F., Instituto de Tlaxiaco, Tezoatlán, Oaxaca; correlaciones Jurásico, Región Norte de la Cuenca de geocronologíay deloslechosrojos del AmericaBulletin,113,1142–1160. of Mexico: Geological Society fragmentation of Carboniferousto Cretaceous assemblyand 114–120. Palaeontographica, Abteilung B, 154, Oaxaca,México: leaves from the Jurassicof gen. et sp. nov., glossopteroid anewgenus of 1660–1674. 1969, Chicago, Lawrence Allen Press, Kan Paleontology Convention, September transition floral (resumen), Jurassic-Cretaceous the 165, 895–896. Oaxaca, México: Science, Middle Jurassic of America,10–14. 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