RT Journal Article
T1 Sandstone petrography of continental depositional sequences of an intraplate rift basin: western Cameros Basin (North Spain)
A1 Arribas Mocoroa, José
A1 Alonso Millán, Ángela
A1 Mas Mayoral, José Ramón
A1 Tortosa, A.
A1 Rodas, Magdalena
A1 Fernández Barrenechea, José María
A1 Alonso Azcárate, Jacinto
A1 Artigas, Rosana
AB The Cameros Basin in Central Spain is an intraplate riftbasin that developed from Late Jurassic to Middle Albian time alongNW–SE trending troughs. The sedimentary basin fill was depositedpredominantly in continental environments and comprises several depositionalsequences. These sequences consist of fluvial sandstones thatcommonly pass upward into lacustrine deposits at the top, producingconsiderable repetition of facies. This study focused on the westernsector of the basin, where a total of seven depositional sequences (DS-1 to DS-7) have been identified.The composition of sandstones permits the characterization of eachsequence in terms of both clastic constituents and provenance. In addition,four main petrofacies are identified. Petrofacies A is quartzosedimentolithic(mean of Qm85F2Lt13) and records erosion of marineJurassic pre-rift cover during deposition of fluvial deposits of DS-1(Brezales Formation). Petrofacies B is quartzofeldspathic (mean ofQm81F14Lt5) with P/F > 1 at the base. This petrofacies was derivedfrom the erosion of low- to medium-grade metamorphic terranes ofthe West Asturian–Leonese Zone of the Hesperian Massif during depositionof DS-2 (Jaramillo Formation) and DS-3 (Salcedal Formation).Quartzose sandstones characterize the top of DS-3 (mean ofQm92F4Lt4). Petrofacies C is quartzarenitic (mean of Qm95F3Lt2) withP/F > 1 and was produced by recycling of sedimentary cover (Triassicarkoses and carbonate rocks) in the SW part of the basin (DS-4, Pen˜ -acoba Formation). Finally, depositional sequences 5, 6, and 7 (Pinillade los Moros–Hortigüela, Pantano, and Abejar–Castrillo de la Reinaformations, respectively) contain petrofacies D. This petrofacies isquartzofeldspathic with P/F near zero and a very low concentration ofmetamorphic rock fragments (from Qm85F11Lt4 in Pantano Formationto Qm73F26Lt1 in Castrillo de la Reina Formation). Petrofacies D wasgenerated by erosion of coarse crystalline plutonics located in the CentralIberian Zone of the Hesperian Massif. In addition to sandstonepetrography, these provenance interpretations are supported by claymineralogy of interbedded shales. Thus, shales related to petrofaciesA and C have a variegated composition (illite, kaolinite, and randomlyinterlayered illite–smectite mixed-layer clays); the presence of chloritecharacterizes interbedded shales from petrofacies B; and Illite and kaoliniteare the dominant clays associated with petrofacies D.These petrofacies are consistent with the depositional sequences andtheir hierarchy. An early megacycle, consisting of petrofacies A and B(DS-1 to DS-3) was deposited during the initial stage of rifting, whentroughs developed in the West Asturian–Leonese Zone. A second stageof rifting resulted in propagation of trough-bounding faults to the SW,involving the Central Iberian Zone as a source terrane and producinga second megacycle consisting of petrofacies C and D (DS-4, DS-5, DS-6, and DS-7). Sandstone composition has proven to be a powerful toolin basin analysis and related tectonic inferences on intraplate rift basinsbecause of the close correlation that exists between depositionalsequences and petrofacies.
PB SEPM (Society for Sedimentary Geology)
SN 1527-1404
YR 2009
FD 2009
LK https://hdl.handle.net/20.500.14352/41944
UL https://hdl.handle.net/20.500.14352/41944
LA eng
DS Docta Complutense
RD 8 may 2024