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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes

Abstract


Pub. Id: A167 (1985)

First Page: 255

Last Page: 274

Book Title: M 39: Seismic Stratigraphy II: An Integrated Approach to Hydrocarbon Exploration

Article/Chapter: Seismic Stratigraphy of Carbonate Depositional Sequences, Upper Jurassic-Lower Cretaceous, Neuquen Basin, Argentina: Chapter 15

Subject Group: Seismic Stratigraphy, Sequence Stratigraphy

Spec. Pub. Type: Memoir

Pub. Year: 1985

Author(s): Robert M. Mitchum Jr., Miguel A. Uliana

Abstract:

The Upper Jurassic-Lower Cretaceous interval in the Neuquen basin, Argentina, provides a good example of carbonate sedimentary response to eustatic sea-level change in a rifted basin that has produced hydrocarbons for over 50 years. We analyzed the area using an integrated stratigraphic approach, including seismic stratigraphy for sequence identification and configuration, wells and outcrops for lithologies and porosity types, and outcrops for paleontological age, ecological data, and detailed physical stratigraphy. Our study shows that the Vaca Muerta, Quintuco, Loma Montosa, and Mulichinco formations are time-transgressive lithofacies units within a series of prograding sequences that laterally filled the shallow, stable basin. There are at least nine clinoform-shaped d positional sequences, and they span the Tithonian, Berriasian, and Valanginian stages. All of them consist of seismically mappable shelf, shelf-margin, slope, and basin facies. In the wells tied to seismic data, the predominantly carbonate reservoir rocks of the Loma Montosa and Quintuco formations represent, respectively, the inner- and outer-shelf segments of individual clinoform sequences. Hydrocarbon-source shales of the Vaca Muerta Formation occur in slope and basin positions. The youngest prograding unit is characterized by shelfal to continental sandstones of the Mulichinco Formation. The degree of shelfward restriction, lateral progradation, and vertical aggradation of the sequences appears to be strongly controlled by global trends of eustatic rises and falls. Other depositional controls, such as thermal subsidence and sediment influx, occur at slow, nearly constant rates in medial to late stages of basin evolution.

An idealized shelf-to-basin lithologic model of a given sequence progresses from terrestrial sandstones and shales through marine inner-shelf micritic limestone, dolomites, and shales; middle-shelf oolitic and skeletal carbonates and shales; outer-shelf molluscan-micritic limestone and shales; and slope and basin dark organic shales.

Outcrops along the western basin margin exhibit depositional characteristics similar to those of the subsurface. In the western outcrop area, lithostratigraphic units are time-transgressive from south to north toward the basin center. In the northwestern outcrop area (Malargue), the timing and depositional response to eustatic changes can be documented through interpretation of detailed stratigraphic and paleontologic observations by other authors.

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