SEMINAR: MGG Student Seminar, Weds Feb 22 - Irena Maura and Noelle Van Ee

[Kelly Gibson <kgibson@rsmas.miami.edu>]

MGG Student Seminar Series presents:

Irena-Andisa Maura - Deepwater Re-Sediemented Carbonate

          and

Noelle Van Ee - Reef Sit on Reefs: Antecedent Topography on Glover's Reef, Belize

Wednesday February 22, 2012

12:00-1:00pm

SLAB Seminar Room

Abstracts below

Deepwater Re-Sedimented Carbonate

Irena Maura 

In the search for new carbonate plays, deepwater re-sedimented carbonate such as slumps, breccias and turbidites received new attention. Unlike, deepwater sandstones, deepwater re-sedimented carbonate are rarely observed and remain poorly understood. To date, only a few reservoirs are producing from carbonate breccias and/or turbidites.
Maiella is an outstanding outcrop to look at in order to studying about re-sedimented carbonate. In the Maiella, the adjacent deepwater basin and carbonate platform sections are exposed and undisturbed. Moreover, the aim of the project is to assess the reservoir potential of Cretaceous to Tertiary deepwater re-sedimented carbonate successions in the slope and the basin adjacent to the Maiella platform, Italy. Outcrops in the Abruzzi and a core from Adriatic offshore through coeval slope and basinal facies provide the subsurface information for the assessment. The analysis shows that indeed deepwater re-sedimented carbonate has a potential to become a reservoir. The better reservoir quality is observed in the Cretaceous section where the porosity can reach 28% and permeability up to 522 mD.
The better reservoir quality of the Cretaceous is related to the original mineralogy and the resultant diagenetic potential. During the Cretaceous, calcite is the predominant carbonate mineral, while in the Tertiary most carbonate production is aragonite. The metastable aragonite has a high diagenetic potential and is subject to dissolution and re-precipiation. This process produces more cement and tighter rocks.   

REEFS SIT ON REEFS: ANTECEDENT TOPOGRAPHY ON GLOVER’S REEF, BELIZE

Noelle J. Van Ee, Gregor P. Eberli, & Flavio S. Anselmetti

Many researchers disagree on what controls reef distribution and morphology. The location of Glover’s Reef proximate the North American-Caribbean plate boundary and along a known precipitation gradient make it an ideal candidate for studying possible controls. The purpose of this study is to test existing hypotheses of meteoric dissolution and structural control on Glover’s Reef by 1) imaging and mapping the relationship between antecedent topography, platform morphology, and patch reef distribution, and 2) determining if the antecedent topography is karst, structural, or growth-induced. To this end, we use a single-channel seismic survey of approximately 111 km of grid lines in conjunction with a N-S rotary core transect. 
We find no evidence of structural control or a Pleistocene surface tilted toward the south; rather, the underlying Pleistocene surface is relatively flat except for beneath patch reefs. In fact, 93% of surveyed Holocene patch reefs are located on Pleistocene topographic highs. Furthermore, in situ reef facies in patch reef cores indicate that these highs are growth-induced: reefs sit on reefs. This is in contrast to Purdy’s (1974) theory that antecedent topography in Belize is primarily caused by dissolution. Similarly, the observed lagoon bathymetry is caused by a wedge of Holocene sediment that is thickest in the NE corner of the lagoon and thins southward, not greater dissolution of the Pleistocene surface in the south of the platform. This work has implications for understanding Quaternary tectonics along the North American-Caribbean plate boundary and predicting the occurrence of reef facies in the geological record. 

.....................
Kelly Gibson
Graduate Student, Marine Geology and Geophysics
Rosenstiel School of Marine and Atmospheric Science, University of Miami
4600 Rickenbacker Cswy Miami FL, 33149

Office: 305.421.4810 x6
Email: kgibson@rsmas.miami.edu