Sedimentary petrology — A guide to paleohydrogeologic analyses, example of sandstones from northwest Gulf of Mexico

Abstract

Petrographic data have rarely been used in hydrogeologic studies, yet the aquifer's rocks record to varying extents the history of rock-water interaction in the aquifer. Recognition of paleohydrogeologic regimes can provide insights into porosity and permeability trends, groundwater chemistry, the formation of petroleum and mineral deposits, and the extrapolation of hydrogeologic processes into the future (with applicability to problems of waste disposal). In the northwestern Gulf of Mexico Basin sandstones, diagenetic features are tabulated and related to paleohydrogeologic systems. Distinctive diagenetic patterns exist in the syndiagenetic, teleogenetic, and burial diagenetic regimes. Less well documented are the diagenetic patterns in sandstones within the low-grade metamorphic or free-convection regimes. These diagenetic features may be useable in other sandstone aquifers (or reservoirs) in identifying paleohydrogeologic systems and developing an aquifer's history. In the sandstones of the northwestern Gulf of Mexico (and probably in other passive continental margins), sandstone petrographic features are shown to record meteoric versus overpressured, compactional flow systems.