Presence of charcoal as evidence of paleofires in the Claromecó Basin, Permian of Gondwana, Argentina: Diagenetic and paleoenvironment analysis based on coal petrography studies

ARZADÚN, GUADALUPE; CISTERNAS, MARÍA EUGENIA; CESARETTI, NORA NOEMÍ; TOMEZZOLI, RENATA NELA

GeoResJ

Elsevier

Año: 2017

2214-2428

The PANG0001 well, situated in the Claromecó Basin, Argentina, involves rocks that belong to the TunasFormation, Permian of Gondwana. It is composed of fine to medium sandstones intercalating with blackand green mudrocks and three coal seams up to 3m thick. In the coals, a petrographic analysis was carried outto analyze the depositional environment and the diagenesis level reached by the Tunas Formation. The coalsare composed of mono-maceral bands of Collotelinite and Gelinite, from the Vitrinite Group, or Fusinite, fromthe Inertinite Group. They were deposited in a wet swampy forest with rises and decreases of the phreaticlevel. The presence of inertinite or charcoal evidence the occurrence of palaeo-fires during the Permian. Thevitrinite reflectance values are between 1.3% and 2.38%. The coals classify as semiantracitic to low volatilebituminous, with 10 to 25% of volatile matter. The vitrinite reflectance values indicate temperatures between140°C and 190 °C. The Tunas Formation reaches the oil to methane gas window, into a catagenesis to metagenesisrange related to the organic matter diagenesis. Coal petrography is a good method for the environmentand diagenesis analyses applied to the Tunas Formation