Geological Society of America

T148 Basin Analysis, Strike-Slip Faults, and Tectonics I: Honoring the Contributions of Paul Umhoefer

Tuesday, 11 October 2022
8:00 AM - 12:00 PM
607

AGE, GEOCHEMISTRY, AND TECTONIC SIGNIFICANCE OF QUATERNARY BASALTS ASSOCIATED WITH TRANSFORM FAULTS OF THE ANATOLIA-ARABIA-AFRICA TRIPLE JUNCTION

Paper number: T148-4
Program: Technical Sessions
Time: 8:45 AM – 9:00 AM

Authors

Michael Cosca Presenting Author
Geology, Geophysics, and Geochemistry Science Center, Denver, CO
Mary R. Reid
Northern Arizona University, Flagstaff, AZ
Jonathan Delph
Purdue University, West Lafayette, IN
Gonca Gençalioğlu Kuşcu
Muğla Sıtkı Koçman University, Kötekli-Muğla
Janne Blichert-Toft
Ecole Normale Supérieure de Lyon, Université de Lyon, Lyon
Wayne R. Premo
Geology and Environmental Change Science Center, Denver, CO
Donna Whitney
Washington State University, Pullman, WA
Christian Teyssier
University of Minnesota, Minneapolis, MN
Bora Rojay
Middle East Technical University, Ankara

Abstract

Mafic volcanism, active seismicity, vigorous geothermal fluid circulation and mineralization are commonly associated with triple junctions. In this study we demonstrate that ⁴⁰Ar/³⁹Ar dating of mafic volcanism associated with the Anatolia-Arabia-Africa triple junction (A³ triple junction) can also be used to constrain the onset of tectonic escape of the Anatolian plate. The A³ triple junction, located near the Gulf of İskenderun in the eastern Mediterranean, is a trench-transform-transform system that includes two major, dominantly left-lateral transform faults: the East Anatolian fault zone (the Anatolia-Arabia plate boundary) and the Dead Sea fault zone (the Arabia-Africa plate boundary). Quaternary alkaline basalt (including basanite) from the Toprakkale and Karasu volcanic fields are investigated within a broad zone of transtension associated with these plate boundary faults near the İskenderun and Amik Basins, respectively. Seismic velocities obtained primarily from the Continental Dynamics-Central Anatolian Tectonics project (CD-CAT) show abrupt contrasts in lithospheric thicknesses under the triple junction, from ~60 km beneath the Arabian margin to >100 km beneath central Anatolia. Here we present ⁴⁰Ar/³⁹Ar geochronology, whole rock geochemistry, Sr, Nd, Hf, and Pb isotopes of basalts from each volcanic field and compare their mantle source regions and equilibration depths to the seismically imaged lithosphere-asthenosphere boundary. These results will be discussed within a broader context of regional magmatism and mantle structure associated with the inception and migration of the triple junction, which also has implications for dating tectonic escape of the Anatolian microplate.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-378434

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