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 [29], 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