Surface And Shallow Subsurface Geology Of Texas Submerged Lands
Authors: Morton Robert A. , McGowen Joseph H. , Berryhill Henry L. , Holmes Charles W. 
Published: October 2008

A comprehensive geological investigation is being conducted of Texas-owned submerged lands which include the bays, lagoons, and inner continental shelf extending from the Gulf shoreline seaward for 10.3 miles. The study is a joint effort between the Bureau of Economic Geology and the U. S. Geological Survey with state funding from the Coastal Zone Management Program of the General Land Office of Texas. Data collection consists of 6700 bottom sediment samples and 4100 nautical miles of high-resolution seismic reflection profiles. Sediment samples were sub sampled for textural and geochemical analyses and descriptions of benthic fauna. Practical applications include delineation of (1) potentially active faults and shallow diapiric structures, (2) high concentrations of heavy metals, (3) biologically productive areas, (4) bottom substrates with markedly different engineering properties and (5) environmental assessment of pollutants in the shelf and estuarine systems.

Basic geological studies will include seismic stratigraphy as well as geometry, facies distribution, and chronology of Quaternary sediments. Sedimentological data will augment other efforts such as mapping of mineral resources and determination of sediment budget. Preliminary results include lithofacies maps of surface sediments based on a three component classification (sand, mud, shell). These maps show that fault related topographic features on the inner Texas shelf control sediment type in some areas. High concentrations of shell and relict sediments, as well as major faulting, are closely related to fluvial-deltaic systems such as the Holocene Rio Grande and Brazos Colorado deltas. Relative rates of sedimentation and general directions of sediment dispersion are inferred from sediment types, thicknesses, textures, and trace element distributions.

INTRODUCTION

The state owned submerged lands of Texas are vast. They encompass nearly 6000 sq. miles and extend from Mexico to Louisiana. The area includes the bays, estuaries, and lagoons as well as the inner continental shelf 10.3 miles seaward of the Gulf shoreline (fig. 1). There are many uncertainties as to the future utilization of the state submerged lands, and we are probably incapable of anticipating all the potential uses for these areas. We can, however, expect multiple and diverse uses related to food production, energy production, recreation, resource extraction, industrial processing, transportation, and the like. Initial planning for many of these activities requires a knowledge of the regional geology, the active geological processes, and the potential environmental impacts of human activities.

A comprehensive investigation of the state submerged lands is being conducted in order to establish the extant geological and biological conditions and to develop a baseline inventory of data for future environmental monitoring. Support for this comprehensive research project was provided by (1) funding from the Coastal Zone Management Program of the Texas General Land Office to the Bureau of Economic Geology (McGowen and others, 1977) and (2) substantial financial and logistical contributions made through the joint research program between the U. S. Geological Survey and the Bureau of Economic Geology.