The age of the first pulse of continental rifting associated with the breakup of Pangea in Southwest Iberia: new palynological evidence

• Published in: Journal of Iberian geology Vol. 48; no. 2; pp. 181 - 190
• Main Authors: Vilas-Boas, Margarida, Paterson, Niall W., Pereira, Zélia, Fernandes, Paulo, Cirilli, Simonetta
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 2022; Springer Nature B.V
• Subjects: Age; Basins; Earth and Environmental Science; Earth Sciences; Geology; Orogeny; Research Paper; Rifting; Sedimentation; Sedimentation & deposition; Structural Geology; Triassic; Unconformity; Upper Triassic; Disconformidad Varisca; Cuenca del Algarve; Palynology; Triásico Superior; Algarve Basin; Variscan unconformity; Palinología; Portugal
• ISSN: 1698-6180; 1886-7995
• DOI: 10.1007/s41513-022-00189-0

In this work, we report the first palynological age for the base strata of the Silves Sandstones of the Silves Group in the Algarve Basin, located in Southern Portugal. The group is the oldest sedimentary unit of the Algarve Basin and was deposited unconformably over late Pennsylvanian turbidites of the Mira Formation, which were folded and faulted during the Variscan Orogeny. The Silves Group comprises a detrital red bed succession, representing the earliest phase of sedimentation associated with the initial rifting of Pangaea. Macrofossils are rare, occurring predominantly in the top layers of this group, and do not accurately constrain the age of the entire group's deposition. From an outcrop exposed in the central Algarve, a grey mudstone bed positioned 2.5 m above the Variscan unconformity plane yielded palynomorphs that date the beginning of sedimentation in this basin to the early Carnian age (Late Triassic). The moderately well preserved and low-diversity palynological association comprises Aulisporites astigmosus , Enzonalasporites densus, Ovalipollis pseudoalatus , Samaropollenites speciosus , Tulesporites briscoensis and Vallasporites ignacii , among others, and is indicative of an early Carnian age.