Trace Fossils and Fluvial Architecture of the Miocene Vinchina Formation, Vinchina Basin, northwest Argentina
Date
2021-01-18
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0003-3320-9620
Type
Thesis
Degree Level
Masters
Abstract
Our understanding of the ichnology of fluvial systems has increased during the last decades due to the integration of trace fossils and sedimentary facies. However, trace-fossil distribution within the framework of fluvial architecture (geometry and three-dimensional assemblage) has been overlooked. The Miocene Vinchina Formation in northwest Argentina is host to massive outcrops of fluvial deposits. In three outcrops along the La Troya creek, deposits of anastomosing and braiding fluvial systems were studied. Eight architectural elements were identified: multistorey sandy channels, amalgamated sandy channels, heterolithic multistorey channels, channels with gravel bars, abandoned channels, muddy floodplain, crevasse splay, and crevasse channels. Three of these elements show bioturbation: crevasse splays, and anastomosing and braided abandoned channels. Vertical simple burrows (Skolithos isp.), freshwater crab burrows (Capayanichnus vinchinensis), and simple horizontal burrows (Palaeophycus tubularis), are the most common trace fossils in the Vinchina Formation. Other elements are Taenidium barretti, Tracheria troyana, Macrauchenichnus isp., and tetradactyl webbed footprints. The ichnofauna identified in the Vinchina Formation illustrates the Scoyenia ichnofacies. In addition, five ichnofabrics are characterized. The position of the water table, substrate consistency, flow energy, and time between depositional events under arid to semi-arid climate conditions were the main parameters controlling bioturbation. Based on detailed observation of the cross-cutting relationship between ichnotaxa, the ichnofabric distribution and the preservation features of the trace-fossils studied, a colonization sequence for each of the subenvironments of the Vinchina Formation is proposed in this study.
Description
Keywords
Ichnology, Trace fossils, Fluvial architecture, Vinchina Formation
Citation
Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geology