Association of Stromatolites and Ooids in the Upper Cretaceous to Eocene Salta Group, NW Argentina

SCHMIDT, W.; MUTTI, M.; GALLI, C.I.

Selva di Val Gardena

Congreso; Dolomieu Conference on Carbonate Platforms and Dolomite.; 2016

American Association of Petroleum Geologist

The association of stromatolites and ooids have been known since the pioneering work of Kalkowsky (1851-1938). Their development through time record environmental, geochemical and evolutionary changes as archives, which are of interest for geoscientist and biologists equally. However, whereas the association of stromatolites and ooids in space is clear, it is in dispute, whether the association of both in time is coeval.The Tres Cruces Basin is the most northern of six subbasins of the Salta Basin (NW Argentina). Its stratigraphic record includes the post-rift Yacoraite Formation (Upper Cretaceous to Eocene). The Formation is composed of alternating bioclastic, oolitic and stromatolitic limestones and marls. The stromatolites are continuously exposed about a kilometre-scale transect and exceptional preserved. The stromatolites form a succession (0.3-1.5m) consisting of basal oolitic grainstone (0.05-0.5m), overlain by planar stromatolites with marked millimetre-scale laminae and incorporated ooids (0.05-0.4m). The laminae grade upward into the oolitic grainstone, whereas the amount of incorporated ooids decrease. Above the stromatolites show domal morphologies, with oolitic grainstone cores (0.1-1.0m). In general the stromatolites show an upward increase in size and complexity and are capped by either laminated marly beds or oolitic grainstone levels.The study aim to perform detailed analysis of these stromatolitic fabrics and to integrate them into a sequence stratigraphic framework in order to infer their environments of deposition controlling their origin and development.