66-4 Paleoenvironmental reconstruction of Cretaceous carbonate series from Oman and its relation to the Oceanic Anoxic Event 1a.

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

Poster Booth No.: 145

Presenting Author:

Kaylie Dana

Authors:

Dana, Kaylie¹, Johnson, Yakira², De Leon, Savanna³, Godet, Alexis⁴, Hinojosa, Jacob⁵, Sharpe, Justin⁶, Suarez, Marina B⁷

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

Abstract:

The Early Cretaceous period was marked by elevated sea temperatures, high sea levels, and widespread oceanic anoxia, including the Oceanic Anoxic Event 1a (OAE1a). Extensive volcanism preceding OAE1a released large volumes of CO₂, driving global warming and disrupting the global carbon cycle. These climatic and geochemical changes triggered significant ecological shifts in shallow marine environments. Fossil evidence from 50 samples collected in Wadi Bani Kharus, Oman, including abundant rudists and orbitolinids, supports the interpretation of warm, shallow marine conditions during this time. This study involves the petrographic and geochemical (elemental and carbon and oxygen stable isotope) analysis of 50 sample. Thin sections are used to identify and characterize the major fossil components, providing insight into the ecology of carbonate-producing ecosystems. Glass beads and pressed pellets are analyzed using X-ray fluorescence (XRF) spectroscopy to quantify concentrations of major and trace elements, respectively. For instance, titanium (Ti) and phosphorus (P), serve as proxies for detrital input and nutrient availability at the time of deposition. Microsampling of slabbed samples for stable isotope analysis allows chemostratigraphic correlation with other globally distributed Early Cretaceous localities, including those in Texas. We hypothesize that during periods of major global environmental change, paleoecological responses to these conditions can be used to assess the degree of ecosystem adaptation. We anticipate that increased nutrient and detrital supply during the OAE1a triggered paleoecological adjustments with the dominance of benthic foraminifera, while the return toward rudist-rich facies after the OAE1a reflect the return to less stressful conditions for benthic ecosystems.

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

doi: 10.1130/abs/2025AM-9617

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