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.

5770
 

We present a method of using fault displacement-distance profiles to distinguish fault-bend, shear fault-bend, and fault-propagation folds, and use these insights to guide balanced and retrodeformable interpretations of these structures. We first describe the displacement profiles associated with different end-member fault-related folding models, then provide examples of structures that are consistent with these model-based predictions. Natural examples are imaged in high-resolution two- and three dimensional seismic reflection data sets from the Niger Delta, Sichuan Basin, Sierras Pampeanas, and Cascadia to record variations in displacement with distance updip along faults (termed displacement-distance profiles). Fault-bend folds exhibit constant displacement along fault segments and changes in displacement associated with bends in faults, shear fault-bend folds demonstrate an increase in displacement through the shearing interval, and fault-propagation folds exhibit decreasing displacement toward the fault tip. More complex structures are then investigated using this method, demonstrating that displacement-distance profiles can be used to provide insight into structures that involve multiple fault-related folding processes or have changed kinematic behavior over time. These interpretations are supported by comparison with the kinematics inferred from the geometry of growth strata overlying these structures. Collectively, these analyses illustrate that the displacement-distance approach can provide valuable insights into the styles of fault-related folding.

Explorer Article

8063
 

Current AAPG Distinguished Lecturer Webster Mohriak is one of the confirmed keynote speakers for the upcoming Atlantic Realm Conjugate Margins Conference, set this August in St. John’s, Newfoundland. Retiring in 2011 after

8049
 

Online registration is open for this year’s AAPG Annual Convention and Exhibition, which will be held April 6-9 at the George R. Brown Convention Center in Houston – and reduced registration fees are still available for those who act fast.

8060
 

Energized by the recent Statoil ASA-operated Bay du Nord light oil discovery in Newfoundland’s offshore Flemish Pass Basin, earth scientists are gearing up to host the fourth Atlantic Realm Conjugate Margins Conference in St. John’s, Newfoundland, Aug. 20-22.

Explorer Emphasis

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.

8051
 

Amid the backdrop of a comparatively soft market for the seismic industry in the coming year or so, oil and gas producers are watching Mexico with considerable expectation after the country passed historic constitutional reforms late last year to end the 75-year-old state monopoly on Mexico’s abundant oil and gas resources.

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 Regions and Sections

8591
 

At first glance, the 47-year-old, unassuming Colombian may not seem like one of the senior leaders of a national oil company. But spending five minutes with Ramirez explains why this passionate individual is one of Colombia’s industry leaders who is leaving a lasting legacy for AAPG.

Wiki Article

9050
 

From AAPG Wiki: A salt flat.

Field Seminar

Salt Lake City Utah United States 14 September, 2014 21 September, 2014 151
 
Salt Lake City, Utah, United States
14-21 September 2014

This course therefore aims at developing an understanding of the unique aspects of lacustrine source rocks, reservoirs, and basin evolution that will aid future exploration and development efforts.

Workshop

Rio de Janeiro Brazil 14 May, 2014 15 May, 2014 1502
 
Rio de Janeiro, Brazil
14-15 May 2014

Join the discussion with leading operators in Latin America and Africa. Gain greater understanding of geological and geophysical attributes of stratigraphic traps in deep water settings. Learn more from equatorial margin exploration analogues.

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