BOLETÍN DE LA SOCIEDAD GEOLÓGICA MEXICANA,

Vol. 54, n.. 1, 2001, p. 10-18

http://dx.doi.org/10.18268/BSGM2001v54n1a2
 
Datos microtermométricos de algunas unidades litológicas del subterreno Teloloapan, Guerrero, México

Eduardo González-Partida1*, Juan Carlos Salinas-Prieto2 y Martha Moctezuma-Salgado2

 

1Unidad de Investigación en Ciencias de la Tierra, Instituto de Geología, Universidad Nacional Autónoma de México, Campus UNAM - Juriquilla, A.P. 1-742, Querétaro, Qro. C.P. 76230
2Consejo de Recursos Minerales, Blv. Felipe Angeles S/N, Carr. México-Pachuca Km 93-5, Pachuca Hgo., CP 42080

* This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The fluid inclusions studied in slates and metavolcanoclastic rocks in Taxco and Taxco El Viejo are liquid dominant liquid + vapor (L+V) with some carbonic gas (CO2). The homogenization temperatures (Th) values range between 205° and 250°C. At low temperature, the fluids are of two types: 1)H2O-NaCl; and 2) H2O+ salts+organic compounds. The first type of fluids presents melting temperatures (Tf) ranging between -7.6° to –19.8°C. This implies salinities between 11.22 to 22.4 % wt. eq. NaCl. Metavolcanoclastic rocks in Teloloapan contain inclusions that are L+V. These inclusions present Th = 141 to 193°C and Tf = -1.5 to –6.4°C, corresponding to salinities between 2.5 and 9.7 % wt. eq. NaCl. The average Th of inclusions within the Amatepec Formation is 132°C with the presence of CO2 in clatherates and abundant liquid uniphasic fluid inclusions.

These microthermic data represent the minimum values for the metamorphic event and show a significant difference with the previously studied Black Schist of Tejupilco. For over twenty years, these Black Schist have been grouped with the metavolcanoclastics rocks of Teloloapan and the Taxco and Taxco El Viejo Schist, which have lead to assign different ages to these rocks (from Paleozoic to Cretaceous). In this paper, we conclude that the Black Schist of Tejupilco (pre-Jurassic) shows a structural and thermal history different to the metavolcanoclastics rocks of the Teloloapan and Taxco, and to the Amatepec Formation of the Jurassic-Cretaceous Teloloapan sub-terrain.

Keywords: fluid inclusions, microthermometry, Formación Amatepec, Teloloapan sub-terrain, Guerrero, Mexico.