Bulletin Article

5773
 

This article describes a 250-m (820-ft)-thick upper Eocene deep-water clastic succession. This succession is divided into two reservoir zones: the lower sandstone zone (LSZ) and the upper sandstone zone, separated by a package of pelitic rocks with variable thickness on the order of tens of meters. The application of sequence-stratigraphic methodology allowed the subdivision of this stratigraphic section into third-order systems tracts.

The LSZ is characterized by blocky and fining-upward beds on well logs, and includes interbedded shale layers of as much as 10 m (33 ft) thick. This zone reaches a maximum thickness of 150 m (492 ft) and fills a trough at least 4 km (2 mi) wide, underlain by an erosional surface. The lower part of this zone consists of coarse- to medium-grained sandstones with good vertical pressure communication. We interpret this unit as vertically and laterally amalgamated channel-fill deposits of high-density turbidity flows accumulated during late forced regression. The sandstones in the upper part of this trough are dominantly medium to fine grained and display an overall fining-upward trend. We interpret them as laterally amalgamated channel-fill deposits of lower density turbidity flows, relative to the ones in the lower part of the LSZ, accumulated during lowstand to early transgression.

The pelitic rocks that separate the two sandstone zones display variable thickness, from 35 to more than 100 m (115–>328 ft), indistinct seismic facies, and no internal markers on well logs, and consist of muddy diamictites with contorted shale rip-up clasts. This section is interpreted as cohesive debris flows and/or mass-transported slumps accumulated during late transgression.

The upper sandstone zone displays a weakly defined blocky well-log signature, where the proportion of sand is higher than 80%, and a jagged well-log signature, where the sand proportion is lower than 60%. The high proportions of sand are associated with a channelized geometry that is well delineated on seismic amplitude maps. Several depositional elements are identified within this zone, including leveed channels, crevasse channels, and splays associated with turbidity flows. This package is interpreted as the product of increased terrigenous sediment supply during highstand normal regression.

DL Abstract

3088
 
DL Abstract

The results of regional deep seismic acquisition in the South Atlantic continental margins have shed new lights on the birth and development of sedimentary basins formed during the Gondwana breakup. Recent models of mantle exhumation as observed in the deep water Iberian margin have been applied extensively to the interpretation of several basins in the Eastern Brazilian and West African conjugate margins. However, the tectonic development of these basins is markedly different from the magma-poor margins, and in this lecture we emphasize the contrasts from the tectono-sedimentary features imaged in deep-penetrating seismic profiles that extend from the platform towards the oceanic crust, which indicate that the Red Sea constitutes a better analogue for the birth of divergent continental margins.

Explorer Article

13184
 
Explorer Article

Despite a few lean times – including a stretch when it was derided as the Dead Sea – the GOM always comes roaring back to life to reclaim its position as the shining star of domestic hydrocarbon production.

Explorer Division Column EMD

13237
 
Explorer Division Column EMD

Over the past year or so we have observed strong evidence that nuclear power is into a new expansion period.

Explorer Emphasis

13200
 

Construction continues for the new GE Global Research’s Oil & Gas Technology Center in Oklahoma City – part of the company’s three-year effort to triple R&D investment in the oil and gas industry. The $125 million facility “will be an incubator for new innovative technologies that will enable safe, efficient and reliable exploration, production, delivery and use of unconventional oil and gas.”

8052
 

Winning Hearts and Minds: Colombia and Latin American prospects offer high promise and difficult hurdles in the form of local political and public resistance.

8050
 

Seismic Outlook: After several years of plenty, 2014 is expected to be a comparatively lean year for the seismic industry, a few localized hot-spots around the world notwithstanding.

Explorer Foundation Update

12439
 
Explorer Foundation Update

It has a new name, a new energy and a new lineup of experts, all primed to spread geoscience knowledge around the world. “It” is AAPG’s newly named Global Distinguished Lecture Program – emphasis on the “global” – which dates back to 1941 but continues to be the Association’s flagship initiative for offering the latest in geologic science to AAPG affiliated geological societies and universities.

Explorer Historical Highlight

13230
 

The relatively recent, very large discoveries offshore Brazil have put pre-salt exploration in the South Atlantic back in the foreground. Pre-salt exploration history, however, is far more ancient and marked with some major successes – but also many failures. Here’s a brief overview of this exploration in West Africa until the M’Boundi discovery, which will be described in detail as it brings some lessons that readers can discover for themselves.

Explorer Regions and Sections

10772
 
Preparation for the FIFA World Cup was not the only event attracting international audiences to Brazil in May. AAPG’s Geosciences Technology Workshop (GTW) Brasil, "Stratigraphic Traps and Play Concepts in Deep Water Settings," brought in 143 geoscientists representing 12 countries from the Americas, Europe and Asia.
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