Cenozoic tectonic and geomorphic evolution of the Longxi region in northeastern Tibetan Plateau interpreted from detrital zircon

Geophysical Research Letters

Huang

Licht

et al. 2019

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The East Asian summer monsoon (EASM) variability on orbital time scale has been extensively investigated in Quaternary loess and speleothems. However, EASM variability during pre‐Quaternary time remains poorly understood. Here we report a continuous upper Miocene cyclostratigraphic record from lake deposits of the Tianshui basin, Northeast Tibet, to reconstruct past variations of the regional hydrological cycle. Our results, combined with previously published cyclostratigraphic records from Northeast Tibet, show that regional lake expansion cycles have been consistently dominated by ~100‐kyr eccentricity forcing over most of the middle to late Miocene. These ~100 kyr cycles corroborate a significant forcing of the East Asian hydrological cycle by Antarctic ice sheet variations at that time. It is, however, unclear if this forcing affected EASM intensity or westerly derived moisture supply to the far east. Regardless of the nature of the main source of precipitation in Northeast Tibet during the Miocene, these results emphasize the existence of a strong teleconnection between Antarctic ice sheet modulations and the continental climate of Asia.

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Middle to Late Miocene Eccentricity Forcing on Lake Expansion in NE Tibet

Geophysical Research Letters

Huang

Licht

et al. 2019

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“…Originally, these basins were parts of the same retro‐arc foreland basin but were later partitioned into individual basins, today enclosed by numerous mountain ranges: the North Qilian to the north, the Kunlun Shan to the south, Ela Shan to the west, and Liupan Shan to the east (Lease et al, ; Liu et al, ). Initial uplift of some of these ranges is dated to the early Eocene (~55–45 Ma), shortly after the onset of the Indo‐Asian collision (Clark et al, ; He et al, ; Wang et al, ), but most of the basin partitioning has been shown to be Neogene (Hough et al, ; Lease, ), with deformation north of the West Qinling Mountains beginning during the early Miocene (Hough et al, ; Liu et al, ). Low‐temperature thermochronology and provenance studies have shown an onset of uplift of the Laji Shan approximately 22 Ma (Lease et al, , ) separating the Xining Basin from the Xunhua and Linxia Basins.…”

Section: Geological Settingmentioning

confidence: 99%

Cyclostratigraphy and Magnetostratigraphy of the Middle Miocene Ashigong Formation, Guide Basin, China, and Its Implications for the Paleoclimatic Evolution of NE Tibet

Paleoceanog and Paleoclimatol

Shen

Licht

et al. 2018

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Recent tectonostratigraphy studies have shown that Northeast Tibet underwent significant tectonic uplift and basin partitioning at 13-8 Ma. This time window is also a period of significant changes in Asian monsoonal intensity, mechanisms of which remain poorly understood. Though many studies have tried to decipher paleoclimatic trends from sedimentary archives in Northeast Tibetan basins, it is often hard to distinguish local orographic effects from regional climate changes in such a tectonically active context. Here we investigated the sedimentary record of the Ashigong Formation, Guide Basin, in order to better constrain the Tibetan paleoenvironmental evolution and link it to uplift episodes and monsoonal evolution. By studying the lithology, magnetostratigraphy, redness, magnetic susceptibility, and elemental content of ã 500-m section, we show that the Ashigong Formation was deposited in a saline paleolake between 14.4 and 10 Ma. Lake expansion displayed cyclic variations following~100-kyr cycles and weaker~41-kyr cycles, reaching its maximum between~11.4 and 10.5 Ma. Our results show that the Guide Basin was hydrologically closed from most of the middle Miocene, confirming previous studies that proposed an early Miocene partitioning of this basin. The maximum lake expansion between 11.4 and 10.5 Ma is coeval to a known peak of monsoonal intensity. This, and the evidence for a strong orbital control on lake expansion, supports a strong monsoonal control on the expansion of middle Miocene Tibet paleolakes. The origin of the~100-kyr forcing on monsoonal moisture supply-different from Quaternary forcing-questions the climatic mechanism of these middle Miocene monsoons and suggests that westerly derived moisture might have also significantly contributed to the regional hydrological budget.

“…In northeastern Tibet, low-temperature thermochronological and detrital zircon analyses indicate that the North Qilian Shan (Zheng et al, 2010;Pan et al, 2013;Wang et al, 2016a), Jishi Shan (Lease et al, 2011), Liupan Shan (Wang et al, 2017), and Haiyuan fault (Duvall et al, 2013) had undergone accelerated exhumation between 14 and 10 Ma. The rapid deformation and exhumation of these mountains would lead to hydrologic separation in the adjacent basins, such as Xunhua and Linxia basins (Hough et al, 2011), and to a high sedimentation rate for foreland basins and new detrital zircon components (Lease et al, 2012;Saylor et al, 2017).…”

Section: Uplifts Of the Plateau Margins Linked To This Asian Dryingmentioning

confidence: 99%

Three main stages in the uplift of the Tibetan Plateau during the Cenozoic period and its possible effects on Asian aridification: A review

Shen

Pang

2018

Preprint

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Abstract. The Tibetan Plateau uplift and its linkages with the evolution of the Asian climate during the Cenozoic are a research focus for numerous geologists. Here, a comprehensive review of tectonic activities across the Tibet shows that the development of the Tibetan Plateau has undergone mainly three stages of the uplift: the near-modern elevation of the central Tibet and significant uplift of the northern margins (~ 55–35 Ma), the further uplift of the plateau margins (30–20 Ma), and a rapid uplift of the plateau margins again (15–8 Ma). The first uplift of the plateau during ~ 55–35 Ma forced the long-term westward retreat of the Paratethys Sea. The high elevation of the central Tibet and/or the Himalayan would enhance rock weathering and erosion contributing to lowering of atmospheric CO2 content, resulting in global cooling. The global cooling, sea retreat coupled with the topographic barrier effect of the Tibetan Plateau could have caused the initial aridification in central Asia during the Eocene time. The second uplift of the northern Tibet could have resulted in the onset of the East Asian winter monsoon as well as intensive desertification of inland Asia, whereas the central-eastern in China became wet. The further strengthening of the East Asian winter monsoon and the inland Asian aridification during 15–8 Ma was probably associated with the Tibetan Plateau uplift and global cooling. Therefore, the uplift of the Tibetan Plateau plays a very important role in the Asian aridification.