RT Journal Article
T1 Lacustrine microbialite pinnacles in the Palaeogene of Patagonia, Argentina: Facies and controls
A1 Alonso Zarza, Ana María
A1 Cabaleri, Nora G.
A1 Huerta, Pedro
A1 Armella, Claudia
A1 Rodríguez Berriguete, Álvaro
A1 Monferran, Mateo D.
A1 Gallego, Oscar F.
A1 Ubaldon, María Cecilia
A1 Silva Nieto, Diego
AB Large carbonate microbialite build-ups are relatively uncommon in ancient fresh-water lacustrine basins as compared with those marine and saline environments. This paper discusses the formation of a large continental lacustrine deposit, the Oligocene-Miocene Carinao Formation in Argentina, which contains large bioherms. The lacustrine formation occurs in N-S corridor and is mostly composed by meter scale pinnacles and sheet-like carbonate beds that grade to detrital deposits towards the more subsident southern areas. The main facies are autochthonous and allochthonous limestones and detrital deposits. The autochthonous limestones include the carbonate pinnacles, which are about 4 m high and 0.5 m in diameter and coalesce laterally to form very continuous beds (several kms). The pinnacles are formed by plate-like, dome, vertically elongated and irregular horizontal bioherms, most of them with radial structure. The bioherms are boundstones of fibrous (fans and spherulites) and feather calcite crystals, micrite and inequigranular calcite mosaics. Both biogenic and abiogenic processes interfered in carbonate precipitation. Allochthonous limestones include peloidal, ostracod and intraclastic limestones, some containing coated grains. Polymictic conglomerates and cross-bedded hybrid arenites deposited in a fluvial-deltaic system located at the southwest of the basin. δ13C values vary between −0.4 and −3.2‰ VPDB and δ18O are comprised between −5.7 and −8.6‰ VPDB. The 87Sr/86Sr ratios range between 0.7061 and 0.7056. The Carinao Formation deposited in a fresh-water lake, sourced by meteoric and deep-groundwater. Tectonics was a main control determining the configuration of the lake system, the water supply and the alignment of some bioherms. The vertical succession or the different bioherms morphologies reflects well the lake level changes controlled by both tectonic and climate.
PB Elsevier
SN 0037-0738
YR 2020
FD 2020-10
LK https://hdl.handle.net/20.500.14352/6612
UL https://hdl.handle.net/20.500.14352/6612
LA eng
NO Ministerio de Ciencia e Innovación (MICINN)
NO Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
DS Docta Complutense
RD 23 jul 2024