Coalification history of the Stephanian Ciñera- Matallana pull- part basin, NW Spain: Combining anisotropy of vitrinite reflectance and thermal modelling

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autor(en): de Wall H
Zeitschrift: International Journal of Earth Sciences
Jahr der Veröffentlichung: 2004
Band: 93
Heftnummer: 93
Seitenbereich: 92-106
ISSN: 1437-3254


Abstract


The Stephanian Cinera-Matallana Basin of NW Spain comprises 1,500 m of alluvial to lacustrine coal-bearing sediments, which were deposited in a late Variscan transtensional/transpressional pull-apart setting. The relationship between coalification pattern and rock deformation was evaluated by measurements of the anisotropy of vitrinite reflectance (AVR). The AVR ellipsoids reveal both pre-tectonic elements related to the bedding fabric and syn-tectonic elements related to folding, producing biaxial ellipsoid shapes with the maximum reflectance parallel to fold axes. The mean coalification gradient for the Stephanian succession is about 0.62 %Rr/km. Calculations of the mean palaeogeothermal gradient are presented on the basis of three different empirical equations. A palaeo-geothermal gradient of 85 degreesC/km is considered the most realistic, with an overburden of about 1,000 m. 1-D numerical modelling of the burial history results in two possible scenarios, the most preferable involving a palaeo-heat flow of 150 mW/ m 2 and an overburden of ca. 1,050 m. These results indicate that maximum coalification was related to a localised but high palaeo-heat flow/-geothermal gradient. The anisotropy of vitrinite reflectance highlights the interactive and transitional nature of sedimentary compaction and rock deformation on the maturation of organic material within strike-slip fault zones.



FAU-Autoren / FAU-Herausgeber

de Wall, Helga Prof. Dr.
Professur für Tektonik

Zuletzt aktualisiert 2018-11-08 um 01:12