Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 58 Number 1: 6-21 - April 1996

A publication of the National Speleological Society

Geology of a Large, High-Relief, Sub-Tropical Cave System: Sistema Purificación, Tamaulipas, Mexico
Louise D. Hose

Abstract

Sistema Purificación, a large cave system in the northern Sierra Madre Oriental of México, is developed in the middle Cretaceous Tamaulipas and overlying Tamabra Formations. The 400 m thick sequence of carbonates formed in a basinal to peri-platform environment north and northeast of the simultaneously developing, large carbonate Miquihuana Platform. The Tamaulipas Formation is stratigraphically underlain by shaly limestone, shale, sandstone, and conglomerate of the Early Cretaceous Taraises, the Late Jurassic La Caja, and the Late Jurassic La Joya Formations.

The cave system is within the west flank of the Huizachal-Peregrina anticlinorium, one of many large Laramide folds making up the Sierra Madre Oriental. Most of the lateral shortening within the carbonates was accommodated by slippage along décollement surfaces and abundant second-, third-, and fourth-order folds. Except along décollement surfaces, faults are rare and have separations of less than three meters. Steeply inclined joints mostly trend ~N5°W and represent axial plane cleavage resulting from Laramide folding.

The principal geologic factors controlling the development of the Sistema Purificación are the stratigraphy and structure of the area. Passages in the upper and lower cave commonly form along the intersection of joints and bedding planes, sub-parallel to the dip. The middle part of the cave is within a third-order, anticlinal-synclinal pair whose north-south trending axial surfaces are about 150 m apart. Passages are mostly developed sub-parallel to the axial surfaces where cleavage provides zones of permeability and enhanced conduit development.

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