Tectonomorphic Influence on Late Cretaceous-Paleogene Sediment Provenance and Dispersal Through West and South Texas From Detrital Zircon Geochronology

Abstract

Spatiotemporal variations in tectonic style, as expressed by evolving topography, exert a primary control on how sediment is generated and transported from source to sink in terrestrial systems and can influence basin-fill architecture, reservoir presence, and quality. During Late Cretaceous-Paleogene time, Texas was situated in a transitional tectonomorphic landscape between nascent Laramide topography and the Mexican Cordillera. There is considerable uncertainty surrounding the Cretaceous-Paleogene sediment routing systems that dissected this region, including dispersal pathways, catchment extent, and debouchment locations. A robust sediment-routing framework is vital to estimating sediment delivery to the Gulf of Mexico, and, broadly, understanding source-to-sink sediment transfer in systems defined by distinct, evolving tectonomorphic provinces.

We present new, depth-profiled LA-ICP-MS detrital zircon (DZ) U-Pb ages (7119 ages from 52 samples) from Cretaceous-Paleogene fluvial-deltaic sediments in south Texas and the Tornillo Basin of west Texas that offer new insights into the stratigraphic and sediment-dispersal evolution of the Texas source-to-sink system. DZ U-Pb age spectra are characterized by dominant Paleogene-Late Cretaceous age modes, subordinate Jurassic, 1.1, 1.4, and 1.7 Ga and minor Permo-Triassic, Silurian-Ordovician, and Neoproterozoic age modes, and a scarcity of Early Cretaceous DZ ages, typical of sources from the Western U.S. but not from western Mexico. DZ core and rim age relationships show three main clusters: Jurassic cores with Late Cretaceous rims, 1.1 Ga cores with Ediacaran-Ordovician rims, and 1.7 Ga cores with Late Cretaceous-Paleocene rims. Detrital zircon U-Pb ages, including core and rim relationships, suggest that south Texas rivers received sediment from a mixture of recycled sedimentary, volcanic, and basement source terranes in southeastern Arizona, northeastern Mexico (Chihuahua Trough, Sabinas Uplift, and Coahuila Block) and southern Colorado/New Mexico (e.g., Colorado Mineral Belt). This interpreted catchment area is extensive, incorporating large portions of the southwestern U.S. and northeastern Mexico where it drained a tectonically active hinterland characterized by first-cycle magmatic input and sedimentary recycling of Laramide inversion structures. This study demonstrates the control a dynamic, evolving tectonomorphic landscape exhibits on the sediment-dispersal evolution of long-lived, major river systems.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018