RT Journal Article
T1 Organic-Rich facies in the Sinemurian and Pliensbachian of theLusitanian Basin, Portugal: Total organic carbon distribution andrelation to transgressive-regressive facies cycles
A1 Duarte, Luís Vitor
A1 Silva, Ricardo
A1 Oliveira, Luiz Carlos Veiga de
A1 Comas Rengifo, María José
A1 Silva, Francisco
AB The upper Sinemurian to Pliensbachian series of the Lusitanian Basin (Portugal) correspond to marly limestonesediments rich in benthic and nektonic macrofauna. This sedimentary record includes several intervals of organicrichfacies, which are particularly well developed in the western sectors of the basin. They correspond to grey anddark marls locally showing strong lamination (black shale type) and are recognized as one of the most importantpotential oil source rocks. This study shows the vertical and lateral distribution of these organic-rich intervals,supported by over 550 total organic carbon (TOC) determinations. The results presented reveal two importantintervals, with several black shale occurrences, in the Oxynotum(?)–Raricostatum (Polvoeira Member of Água deMadeiros Formation) and at the top of the Ibex-upper part of Margaritatus zones (top of the Vale das Fontes Formation),showing in the distal (western) sectors up to 22% and 15% TOC, respectively. TOC values decrease progressivelytowards the proximal sectors, the youngest organic-rich interval being the most expressive at the basinscale. This lateral TOC distribution, the facies stacking patterns and the decrease observed in benthic macrofaunaconfirm that these intervals are related to 2nd-order transgressive phases. 2nd-order regressive phases, developedduring the uppermost Raricostatum and Spinatum zones respectively, show lower TOC values.TOC distribution combined with other stratigraphic and sedimentological parameters enabled seven facies mapsto be created for the time interval studied. At the regional scale, this study shows for the first time the goodsimilarity between the upper Sinemurian-Pliensbachian sedimentary successions of the Lusitanian and Basque-Cantabrian basins.
PB Instituto de Ciencias de la Tierra "Jaume Almera" (Barcelona)
SN 1695-6133
YR 2010
FD 2010
LK https://hdl.handle.net/20.500.14352/41905
UL https://hdl.handle.net/20.500.14352/41905
LA eng
DS Docta Complutense
RD 7 may 2024