100-5 Paleogeographic Evolution of Oman and Egyptian Terranes of the Arabian-Nubian Shield through the Neoproterozoic

Session: Snowballs, Unconformities, BIFs and Beyond: Navigating the Neoproterozoic Rock and Climate Records Using Geochronology

Presenting Author:

Yiming Zhang

Authors:

Zhang, Yiming¹, Swanson-Hysell, Nicholas L.², Macdonald, Francis A.³, Zoheir, Basem⁴, Koran, Isabel⁵, Adrian Tasistro-Hart, Adrian⁶, Jay, Annabel⁷, Wan, Zijun⁸, Schmitz, Mark D.⁹

(1) University of Minnesota, Minneapolis, MN, USA, (2) University of Minnesota, Minneapolis, MN, USA, (3) UC Berkeley, Berkeley, CA, USA, (4) Department of Geosciences, King Fahd University for Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia, (5) Earth and Planetary Science, Berkeley, CA, USA, (6) Earth and Planetary Science, Berkeley, CA, USA, (7) Geology, Northfield, MN, USA, (8) Geology, Northfield, MN, USA, (9) Boise State University, Boise, ID, USA,

Abstract:

The Arabian-Nubian arc terranes represent the largest known region of Neoproterozoic accretionary crustal growth, yet their positions within the ancient Mozambique Ocean are poorly constrained. Improved paleogeographic and temporal constraints are necessary to evaluate hypotheses connecting paleogeography to climate including the initiation of Snowball Earth. 

We report geochronologic and paleomagnetic data from the late Tonian (ca. 726 Ma) Shaat dike swarm in southern Oman that constrains the northern margin of the ocean. We integrate these data with new geochronology from the early Cryogenian Wadi Ghadir ophiolite, the late Cryogenian Kadabora pluton, and the Ediacaran post-tectonic Kadabora dike swarm in the Central Eastern Desert of Egypt. Paired with in-development paleomagnetic data, these units have the potential to directly constrain the position of the Arabian-Nubian Shield.

The Shaat dikes have well-resolved magnetization held by magnetite that passes a conglomerate test, a reversal test, and a baked contact test. The resulting paleomagnetic pole indicates that Oman was at a paleolatitude of 37.5±2.5° and was rotated counterclockwise ~80° from its present-day orientation. This position is consistent with Oman forming a contiguous plate with India and South China on the northern margin of the Mozambique Ocean that brackets the Arabian-Nubian arcs to the south. This configuration implies a Mozambique Ocean >5500 km wide prior to its closure that led to crustal growth during Gondwana assembly. Preliminary data from the Wadi Ghadir ophiolite and Kadabora dike swarm offer critical constraints on the timing and kinematics of terrane formation, deformation, and accretion within the Arabian-Nubian Shield. Integrated with data from Oman, they help illustrate the configuration of the Mozambique Ocean and its closure leading up to the assembly of Gondwana. 

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

doi: 10.1130/abs/2025AM-9031

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