Publication Date

2016-08-02

Availability

Embargoed

Embargo Period

2018-08-02

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Marine Geology and Geophysics (Marine)

Date of Defense

2016-06-17

First Committee Member

Gregor P. Eberli

Second Committee Member

Peter K Swart

Third Committee Member

Jose L. Massaferro

Abstract

The Late Jurassic – Early Cretaceous slope and basin sediments of the Neuquén Basin, Argentina, consist mostly of siliciclastic mudstones of the Vaca Muerta Formation. However, carbonate-rich intervals of unknown origin occur at different stratigraphic levels within the Formation. This study aims to determine if these intervals were sourced from adjacent carbonate-rich shelves during sea level highstands. Logs and samples through sections from the southern slope and the basin center provide the information in regards of facies variability and stratal architecture that are placed within a biostratigraphic and sequence-stratigraphic framework. The thickest carbonate-rich interval (up to 70m) is known as the Los Catutos Member. Correlation of sections in the Sierra de la Vaca Muerta reveal a wedge-shape geometry with slump scars and channels in the southern and thicker portion, indicating a slope setting. Cycles within the Los Catutos carbonate-rich interval show an upward increase in carbonate content and skeletal debris. Northward, in the thinner part of the wedge, bed thickness, carbonate and skeletal content decrease indicating a southern origin. The time-equivalent Picún Leufú carbonate platform located further south is the identified as the source of the Los Catutos carbonates that are interpreted to be its periplatform apron. The geochemical evidence of the proximal-distal trend in the d13C signature supports this interpretation. Three younger carbonate-rich intervals in a basinal section in the Puerta Curaco (PC) area have very similar facies as the distal portion of the Los Catutos interval. They are, however, younger than the Picun Leufú platform in the south and are probably sourced from a different direction. No coeval carbonate platforms are exposed in outcrops but time-equivalent shallow-water carbonates are present in cores from the eastern shelf of the Neuquén Basin. The four studied carbonate-rich intervals occur in the regressive portion of sequences and, thus, indicate production and export of carbonates during sea level highstands.

Keywords

Vaca Muerta; Puerta Curaco; carbonate; sequence stratigraphy; isotopes; TOC

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