The Tethys Ocean was compartmentalized into the Mediterranean Sea and Indian Ocean during the early Miocene, yet the exact nature and timing of this disconnection are not well understood. Here we present two new neodymium isotope records from isolated carbonate platforms on both sides of the closing seaway, Malta (outcrop sampling) and the Maldives (IODP Site U1468), to constrain the evolution of past water mass exchange between the present day Mediterranean Sea and Indian Ocean via the Mesopotamian Seaway. Combining these data with box modeling results indicates that water mass exchange was reduced by ~90% in a first step at ca. 20 Ma. The terminal closure of the seaway then coincided with the sea level drop caused by the onset of permanent glaciation of Antarctica at ca. 13.8 Ma. The termination of meridional water mass exchange through the Tethyan Seaway resulted in a global reorganization of currents, paved the way to the development of upwelling in the Arabian Sea and possibly led to a strengthening of South Asian Monsoon.
Bibliographical noteFunding Information:
This study was partially funded by the German-Israel Foundation for Scientific Research and Development (GIF) grant 1-1336-301.8/2016 (MioEast project) awarded to N.D.W., M.F. and C.B. The authors would like to thank IODP for granting access to the samples. We would like to express our gratitude to the Mediterranean Sea Research Center of Israel (MERCI) for supporting participation of Israel in IODP activities, including the recruitment of O.M.B. as a member of Exp. 359. Fieldwork in Malta was partially funded by STSM awarded to O.M.B. under COST Action CA15103 (MEDSALT) and hosted by Prof. Aaron Micallef, who is thanked for his help and discussions. We thank the Maltese Superintendence of Cultural Heritage for sampling permission to R.Z. Special thanks go to Alba de la Vara Fernandez and Paul Meijer for discussions on the effects of gateway restriction on Mediterranean circulation.
© 2019, The Author(s).
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