Abstract This study presents a regional structural analysis and a stratigraphic study in Hidalgo and Querétaro states, east-central Mexico, where strata of the Sierra Madre Oriental foreland fold-and-thrust belt are structurally juxtaposed against Middle (?) and Upper Jurassic back-arc sequences. Rocks of the San Juan de la Rosa Formation were apparently affected by major compressive deformation during the Early Cretaceous (Nevadian?) and Laramide orogenies. Toward the east, the style of deformation is that of a typical foreland fold-and-thrust belt, whose major thrust faults are located at the Zimapán Basin margins flanked by the El Doctor and Valles-San Luis Potosí carbonate platforms. Below the El Doctor thrust, at least seven thrust faults are exposed that crosscut the middle Cretaceous rocks and the enveloping Upper Jurassic-Lower Cretaceous and Upper Cretaceous marly shaly beds in the form of a duplex. The style of deformation between the two carbonate platforms is probably thin-skinned. Speculative, semibalanced cross sections indicate an average shortening between the Zimapán Basin margins of 39.4% of its initial width. Depth to the sole thrust is estimated to be about 2000 m below the present sea level.

Abstract The continental interior of Mexico is characterized by a Late Cretaceous prominent fold-thrust belt that shows characteristics of an eastward-tapering orogenic wedge. According to structural data and geothermometry of the deformation, this wedge is the result of horizontal stresses directed from the west (Pacific domain). The orogenic wedge is bounded to the west by the Guerrero Terrane, which is the second largest juvenile terrane accreted to the North American Cordillera. The possible linkage between the accretion of the Guerrero Terrane and the regional shortening in the Mexican interior is examined in detail in the region comprised between the Sierra de Guanajuato and the Peña de Bernal—Tamazunchale areas. In order to test the accretion hypothesis, we present key stratigraphic, structural, and geochronologic data from the Mexican Cordillera in central Mexico, and discuss the problems that exist in connecting the accretion of the Guerrero Terrane to the orogenic deformation of the Mexican continental interior.

ABSTRACT This study presents the first apatite fission-track results from the Tolimán area, which is located in the western portion of the southern Sierra Madre Oriental, central Mexico. In total, six rock samples from different lithostratigraphic units were dated, adding new results to the thermochronological data set of the Sierra de los Cuarzos–San Joaquín–Tamazunchale transect in the Mexican fold-and-thrust belt. The apatite fission-track ages vary from 84 ± 4 Ma to 52 ± 2 Ma, indicating that the main denudation period of the Tolimán area lasted until the Eocene. Combining our results with previous geological data, we suggest that the western part of the southern Sierra Madre Oriental was uplifted and undergoing erosion during the whole period of development of the Campanian–Ypresian Mexican orogenic system. Therefore, the Tolimán area may be considered as one of the source areas from which clastic materials of the Campanian–Maastrichtian Méndez and Paleocene–Eocene Velasco and Chicontepec Formations were partially derived. Older cooling ages recording the latest Aptian accretion of the Guerrero terrane with the Mexican continental interior were not detected in samples from the Tolimán area.

Abstract Some El Abra Formation carbonate reservoirs produce from fractured and brecciated rocks resulting from paleokarstic events. The western margin of the Gulf of Mexico front of the Sierra Madre Oriental exposes Albian-Cenomanian rocks of the El Abra Formation. In the Actopan Platform, these outcrops allow the study of the paleokarst development in peritidal rocks. Included in the karst are dissolutional, depositional, fracturing, brecciation, and collapse features. Toucasia wackestone beds of restricted-marine lagoonal to intertidal environment overlay the paleokarst. Similar events also occur in subsurface Albian-Cenomanian carbonate rocks around the Gulf of Mexico: Jordan Knoll (eastern Gulf of Mexico) and San Marcos and Cordoba Platforms (northwestern and western Gulf of Mexico). Some of the paleokarsted rock intervals have been studied only by space-core samples or by geophysical methods (Jordan Knoll). The Actopan Platform rocks allow an Albian-Cenomanian model to be developed and to be compared to similar rocks around the Gulf of Mexico.

Abstract Upper Cretaceous-Paleogene strata of northern and central Mexico were deposited in a retroarc foreland basin that was at first narrow but expanded eastward during the Paleogene. New petrographic data and U-Pb detrital zircon ages yield insights into stratirgaphic age of the basin fill, sediment sources, and sediment-dispersal pathways. The basin differs from the contemporary Cordilleran foreland basin of the US to the north in having a dominant volcanic-lithic component in all of its sandstones. Like its northern counterpart, the Mexican basin migrated eastward with time, ahead of an advancing orogenic wedge. Provenance data indicate that the dominant sediment source for all strata was the coeval continental margin arc of western Mexico. Nevertheless, temporal differences in zircon content indicate distant sediment sources in basement and derivative sedimentary rocks of southwestern Laurentia during early (Cenomanian–Turonian) and late (Campanian–Maastrichtian and Paleogene) stages in basin evolution; during an intermediate stage (Coniacian–earliest Campanian), the Laurentian sources were absent and most pre-arc grains were derived from accreted rocks of western Mexico. The initial basin possessed a narrow foredeep filled by sediment-gravity flow deposits filled with dominantly axial sediment transport. Carbonate platforms of eastern Mexico supplied calclithites to the foredeep during early stages of basin formation, indicating the importance of pre-foreland paleotopography on sediment fill. Sediment-dispersal systems evolved in concert with the stages of basin development. During the Cenomanian–Turonian stage, turbidites deposited in the Mesa Central had headwaters as far away as northern Sonora, but headwaters for Coniacian–Campanian deep-water deposits probably lay closer to central Mexico. Although late-stage uppermost Cretaceous–lower Eocene shallow marine and continental strata in the foreland of northeast Mexico were linked to a fluvial drainage basin whose extent was probably the greatest in Mexico, it is unclear if these clastic sediments ever reached the Gulf of Mexico. Partitioning of the distal foreland by inversion of Jurassic extensional basins in Santonian–Campanian time was probably effective at isolating dispersal systems of northern Mexico from time-equivalent sediment-routing systems of northeast-ernmost Mexico and southwestern Texas.

ABSTRACT A comprehensive correlation chart of Pennsylvanian–Eocene stratigraphic units in Mexico, adjoining parts of Arizona, New Mexico, south Texas, and Utah, as well as Guatemala, Belize, Honduras, and Colombia, summarizes existing published data regarding ages of sedimentary strata and some igneous rocks. These data incorporate new age interpretations derived from U-Pb detrital zircon maximum depositional ages and igneous dates that were not available as recently as 2000, and the chart complements previous compilations. Although the tectonic and sedimentary history of Mexico and Central America remains debated, we summarize the tectonosedimentary history in 10 genetic phases, developed primarily on the basis of stratigraphic evidence presented here from Mexico and summarized from published literature. These phases include: (1) Gondwanan continental-margin arc and closure of Rheic Ocean, ca. 344–280 Ma; (2) Permian–Triassic arc magmatism, ca. 273–245 Ma; (3) prerift thermal doming of Pangea and development of Pacific margin submarine fans, ca. 245–202 Ma; (4) Gulf of Mexico rifting and extensional Pacific margin continental arc, ca. 200–167 Ma; (5) salt deposition in the Gulf of Mexico basin, ca. 169–166? Ma; (6) widespread onshore extension and rifting, ca. 160–145 Ma; (7) arc and back-arc extension, and carbonate platform and basin development (ca. 145–116 Ma); (8) carbonate platform and basin development and oceanic-arc collision in Mexico, ca. 116–100 Ma; (9) early development of the Mexican orogen in Mexico and Sevier orogen in the western United States, ca. 100–78 Ma; and (10) late development of the Mexican orogen in Mexico and Laramide orogeny in the southwestern United States, ca. 77–48 Ma.