SPELEOGENESIS AND GEOLOGICAL CONFIGURATION OF LA JOYA CAVE, TAXCO, GUERRERO, MEXICO

La Joya cave is located in the northern of Guerrero state (South of Mexico), in the Coxcatlán karst area. It`s development is asociate to the Aptian-Albian limestones and dolostones of Morelos Formation. This area was affected by different tectonic and magmatic events: 1) shortening related with the Laramide Orogeny (Late Cretaceous-Paleocene), forming folds and thrust faults and 2) NW-SE and N-S strike-slip and normal faults of Taxco-San Miguel de Allende Fault System with Eocene activity and reactivations in the Oligocene and Miocene time, generating regional structures that affect the north area of Taxco, Guerrero.

The La Joya cave is part of the Zacatecolotla-Las Granadas Karst System (ZGKS), where converge the shortening and extensional structures that control the configuration of exokarst and endokarst configuration. In this work, we integrate the structural and geomorphological analysis of the cave and its comparison with external structures, as well as, a preliminary analysis of microthermometry of inclusions fluids in speleothems, that show mixing of meteoric water and hydrothermal fluids, obtained 200 °C in the core rings and 40° in the external rings. This data reveals that La Joya cave was generated in two principal stages: 1) related with a possible hypogenetic origin, due to the nearby of grano-dioritic intrusives aside and the high presence of calcite, quartz and fluorite veins into the cave and 2) epigenetic reactivation with phreatic and vadose conducts in a meandric canyon arrangement. The 3D structures and the geological configuration of the ZGKS allow that La Joya cave gives us a broad overview of the speleogenetic phases on the karst areas of the north of Guerrero state.

Key words: Speleogenesis, La Joya cave, Taxco Guerrero, Fluid Inclusion