KARSTIFICATION IN THE SIERRA MADRE ORIENTAL: A HYDROLOGIC RECORD OF REGIONAL DIAGENESIS

Identification and analysis of major diagenetic processes that evolve landscapes are important to understand the natural resources of a particular region. The Sierra Madre Oriental mountain system of northeastern Mexico has been investigated as a unique lithologic and structural geologic analogue for petroleum carbonate reservoirs due to the immense thickness of Cretaceous limestone and well-exposed Laramide structural deformation. The region north of the Trans-Mexican Volcanic Belt to the Big Bend area of west Texas has undergone intensive karstification; however, this aspect of carbonate diagenesis has seen limited scientific study. These karst systems not only provide information about the geologic evolution of the subsurface, but are important in evaluation of groundwater resources to a growing population.

Many years of cave exploration and mapping have documented over 2500 major cave systems or karst springs in northeastern Mexico, most of which lie in the Sierra Madre Oriental. Included in these are some of the deepest vadose pits (Sotano de las Golandrinas -376m); deepest phreatic caves (El Nacimiento del Rio Mante - 290m); and longest karst systems (Sistema Purification 95.7 km) in the world. Many of the largest karst springs also exist at the base of the mountain range, including the Nacimiento del Rio Coy, with peak discharge values recorded up to 250 cubic meters per second. Other interesting karst systems exist within this geologic province that reflects a diversity of karst development in the Sierra Madre Oriental. Understanding the local and regional scale geologic factors that controlled evolution of these karst systems reveals numerous processes that result in the modern hydrogeologic characteristics of the region.