Jonell, Tara N;
Giosan, Liviu;
Clift, Peter D;
Carter, Andrew;
Bretschneider, Lisa;
Hathorne, Ed C;
Barbarano, Marta;
... Thet, Naing; + view all
(2022)
No modern Irrawaddy River until the late Miocene-Pliocene.
Earth and Planetary Science Letters
, 584
, Article 117516. 10.1016/j.epsl.2022.117516.
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Abstract
The deposits of large Asian rivers with unique drainage geometries have attracted considerable attention due to their explanatory power concerning tectonism, surface uplift and upstream drainage evolution. This study presents the first petrographic, heavy mineral, Nd and Sr isotope geochemistry, and detrital zircon geochronology results from the Holocene Irrawaddy megadelta alongside modern and ancient sedimentary provenance datasets to assess the late Neogene evolution of the Irrawaddy River. Contrary to models advocating a steady post-middle Miocene river, we reveal an evolution of the Irrawaddy River more compatible with regional evidence for kinematic reorganization in Myanmar during late-stage India-Asia collision. Quaternary sediments are remarkably consistent in terms of provenance but highlight significant decoupling amongst fine and coarse fraction 87Sr/86Sr and εNd due to hydraulic sorting. Only well after the late Miocene do petrographic, heavy mineral, isotope geochemistry, and detrital zircon U–Pb results from the trunk Irrawaddy and its tributaries achieve modern-day signatures. The primary driver giving rise to the geometry and provenance signature of the modern Irrawaddy River was regional late Miocene (≤10 Ma) basin inversion coupled with uplift and cumulative displacement along the Sagaing Fault. Middle to late Miocene provenance signatures cannot be reconciled with modern river geometries, and thus require significant loss of headwaters feeding the Chindwin subbasin after ∼14 Ma and the northern Shwebo subbasin after ∼11 Ma. Large-scale reworking after ∼7 Ma is evidenced by modern Irrawaddy River provenance, by entrenchment of the nascent drainage through Plio-Pleistocene inversion structures, and in the transfer of significant sediment volumes to the Andaman Sea.
| Type: | Article |
|---|---|
| Title: | No modern Irrawaddy River until the late Miocene-Pliocene |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.epsl.2022.117516 |
| Publisher version: | https://doi.org/10.1016/j.epsl.2022.117516 |
| Language: | English |
| Additional information: | © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
| Keywords: | Science & Technology, Physical Sciences, Geochemistry & Geophysics, provenance, sediment, Irrawaddy, zircon, isotope geochemistry, petrography, INDO-BURMAN RANGES, U-PB, CENTRAL MYANMAR, DETRITAL ZIRCON, HF ISOTOPES, ARC BASIN, EVOLUTION, PROVENANCE, HIMALAYAN, HISTORY |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10171242 |
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