66-6 Impact of Early Cretaceous Paleoenvironmental Change on Reservoir Quality in Lower Cretaceous series from Wadi Muaydin, Oman

Session: Environmental Instability During Greenhouse Periods: Impact on Terrestrial and Marine Ecosystems (Posters)

Poster Booth No.: 147

Presenting Author:

Yakira Johnson

Authors:

Johnson, Yakira¹, Dana, Kaylie², De Leon, Savana³, Godet, Alexis⁴, Hinjosa, Jacob⁵, Sharpe, Justin⁶, Suarez, Marina B.⁷

(1) University of Texas at San Antonio, San Antonio, Texas, USA, (2) University of Texas at San Antonio, San Antonio, Texas, USA, (3) University if Texas at San Antonio, San Antonio, Texas, USA, (4) University of Texas at San Antonio, San Antonio, Texas, USA, (5) University of Texas at San Antonio, San Antonio, Texas, USA, (6) University of Texas at San Antonio, San Antonio, Texas, USA, (7) The University of Kansas, Lawrence, KS, USA,

Abstract:

The Early Cretaceous experienced several profound paleoenvironmental changes. Specifically, volcanism in the early Aptian triggered the Oceanic Anoxic Event (OAE)1a, which corresponds to a major disturbance in the carbon cycle. OAE1a caused ecological changes in shallow marine environments as well as the deposition of organic black shales in deep marine environments due to the development of anoxic conditions. Carbonate series from Oman detail changes in the carbonate ecosystem due to paleoenvironmental forces during the Early Cretaceous. These series are unique because they belong to the widespread Arabian platform that was straddling the equator during the Early Cretaceous and was subjected to rather dry climatic conditions. Lower Cretaceous limestones of Oman serve as reservoirs for hydrocarbons but understanding the impact of OAEa1-related paleoecological turnover and depositional facies on reservoir quality distribution, like porosity and permeability, is the goal of this study. Field and petrographic data of fifty rock samples from Wadi Muaydin were complemented by carbon and oxygen stable isotope composition, elemental geochemistry, and porosity data. Petrographic analysis of thin sections will inform on the diagenesis of rock samples, providing insights on the type and amount of porosity. Isotope geochemical data will help to complete chemostratigraphic correlation of the studied series with reference curves to identify the signature of the OAE1a, while elemental geochemical data will inform on paleoenvironmental forcing that may have contributed to favorable reservoir properties.  Loss on ignition data will trace carbonate content and estimate the amount of organic matter. We anticipate that depositional textural changes from orbitolinid and rudist floatstone, to mudstone is associated with an increase in detrital input and a decrease in porosity as the OAE1a unfolds

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9152

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