GEOLOGY OF THE BATOPILAS MINING DISTRICT, CHIHUAHUA, MEXICO. (VOLUMES I AND II)
Abstract
The Batopilas mining district is located in the southwestern portion of Chihuahua, Mexico in highly dissected terrain consisting largely of Cretaceous and Tertiary intrusive and extrusive rocks of intermediate to felsic composition, forming the upper and lower igneous series of the Sierra Madre. An early, 85 MY granodioritic phase was followed by Tertiary quartz dioritic phase at 50 MY, and another granodioritic phase at 45 MY. The upper volcanic series occurred at 28 MY. A map of the surface geology was made at a scale of 1:25,000 covering an area of 60 km('2). The Batopilas area was near the source of several of the igneous stages which vented, resulting in great variability in extrusive units. An intrusive phase associated with the 45 MY Las Tahonas unit developed a small porphyry cooper deposit to the west of the town, which is presently in a stage of excellent exposure. The numerous silver deposits occur in a broad arc around the prophyry and several kilometers out. The silver zone is separated from the porphyry by a poor quartz-galena zone. Over 20 km of underground mine workings were mapped at a scale of 1:600, constituting a large part of the 34 plates in this study. Ore bodies constituted pods 50 to 100 m in each of two dimensions and up to 2 m wide in large parallel faults or single major faults and its symoid relatives. They generally occur at inflextions or intersections. Mineralization consists of primary native silver in abundant calcite with minor galena, sphalerite, and argentite. Alteration consists of pyritization, silification, and chlorite-actinolite. Several genetic models for the Batopilas mineralization are possible with the data at hand. The one presently favored envisions a 45 MY porphyry cooper system generating circulating hydrothermal connate systems which leach materials from below or adjacent areas, and redeposit them in the native silver-calcite veins of Batopilas. The low sulfur acrtivity of the mineralizing solutions was caused by special conditions. The Batopilas mining district produced 40 million ounces of silver during the last 350 years, however, no serious mining activity has taken place since 1920. Numerous small but specific targets are identifiable underground, several major fault displacements can be reconstructed to identify vein continuations, unexplored ground between mines can be recognized, and the now recognized zoning pattern can be used to extend potentially mineralized ground.
Subject Area
Geology
Recommended Citation
WILKERSON, GREGG, "GEOLOGY OF THE BATOPILAS MINING DISTRICT, CHIHUAHUA, MEXICO. (VOLUMES I AND II)" (1983). ETD Collection for University of Texas, El Paso. AAI8420096.
https://scholarworks.utep.edu/dissertations/AAI8420096