Tectonic and climate controls on Neogene environmental change in the Zhada Basin, southwestern Tibetan Plateau

Joel E Saylor, Lokin Casturi, Timothy M. Shanahan, Junsheng Nie, Crystal MSaadeh

Research output: Contribution to journalArticle

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Abstract

Evidence for a long-lived, high-elevation plateau contradicts the hypothesis that uplift of the southern Tibetan Plateau was a driver of late Miocene-Pliocene changes in ecology and monsoon strength. We illuminate the mechanisms underlying late Miocene-Pliocene environmental changes using a multi-proxy record from the Zhada Basin, southwestern Tibetan Plateau, between ca. 9.2 and 2.3 Ma. An increase in mean carbonate δ18Oc and d13Cc values, decrease in grain size, and onset of lacustrine deposition at 6.0 Ma is attributed to local tectonic damming and transition from a through-flowing fluvial system to a terminal lake. This is followed at 3.5 Ma by a decrease in lake size indicated by synchronous increase in grain size, progradation of lake-margin depositional systems, increase in δ18Oc values at lake-central locations, and divergence in δ18Oc values between inflowing and lake water. We attribute lake shrinking to decreasing Indian summer monsoon precipitation due to the combined effects of decreased southern Tibetan Plateau elevations and cooler Indian Ocean temperatures. We attribute increased grain size and δ18Oc value variability to changes in fluvial discharge due to increased sensitivity to orbital forcing, itself possibly coupled with onset of glacial conditions at high elevations. These mechanisms link regional tectonic events to Pliocene changes in climate and environmental conditions, including erosion, granularity, sediment accumulation rates, and potentially biological turnover on and around the Tibetan Plateau.

Original languageEnglish (US)
Pages (from-to)919-922
Number of pages4
JournalGeology
Volume44
Issue number11
DOIs
StatePublished - 2016
Externally publishedYes

Fingerprint

Neogene
environmental change
plateau
tectonics
lake
climate
Pliocene
basin
grain size
monsoon
Miocene
orbital forcing
progradation
climate conditions
accumulation rate
lake water
turnover
uplift
divergence
environmental conditions

ASJC Scopus subject areas

  • Geology

Cite this

Tectonic and climate controls on Neogene environmental change in the Zhada Basin, southwestern Tibetan Plateau. / Saylor, Joel E; Casturi, Lokin; Shanahan, Timothy M.; Nie, Junsheng; MSaadeh, Crystal.

In: Geology, Vol. 44, No. 11, 2016, p. 919-922.

Research output: Contribution to journalArticle

Saylor, Joel E ; Casturi, Lokin ; Shanahan, Timothy M. ; Nie, Junsheng ; MSaadeh, Crystal. / Tectonic and climate controls on Neogene environmental change in the Zhada Basin, southwestern Tibetan Plateau. In: Geology. 2016 ; Vol. 44, No. 11. pp. 919-922.
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