Late Miocene hinterland crustal shortening in the Longmen Shan thrust belt, the eastern margin of the Tibetan Plateau

Long&#8208;term (million year time scale) fault&#8208;slip history is crucial for understanding the processes and mechanisms of mountain building in active orogens. Such information remains elusive in the Longmen Shan, the eastern Tibetan Plateau margin affected by the devastating 2008 Wenchuan earthquake. While this event drew attention to fault deformation on the foreland side (the Yingxiu&#8208;Beichuan fault), little is known about the deformation history of the hinterland Wenchuan&#8208;Maoxian fault. To address this gap, thermochronological data were obtained from two vertical transects from the Xuelongbao massif, located in the hanging wall of the Wenchuan&#8208;Maoxian fault. The data record late Miocene rapid cooling and rock exhumation at a rate of 0.9&#8211;1.2 km/m.y. from ~13 Ma to present. The exhumation rate is significantly higher than that in the footwall (~0.3&#8211;0.5 km/m.y.), indicating a differential exhumation of ~0.6 km/m.y. across the fault. This differential exhumation provides the first and minimum constraint on the long&#8208;term throw rate (~0.6 km/m.y) of the Wenchuan&#8208;Maoxian fault since the late Miocene. This new result implies continuous crustal shortening along the hinterland fault of Longmen Shan, even though it has not been ruptured by major historic earthquakes. Our study lends support to geodynamic models that highlight crustal shortening as dominating deformation along the eastern Tibetan Plateau.

Download Full-text

Paleoaltitudinal histories for the northern and southern margins of the Tibetan Plateau during the Late Cenozoic: revealed by GDGTs

10.5194/egusphere-egu21-14073 ◽

2021 ◽

Author(s):

Chihao Chen ◽

Yan Bai ◽

Xiaomin Fang ◽

Haichao Guo ◽

Weilin Zhang ◽

...

Keyword(s):

Tibetan Plateau ◽

Late Miocene ◽

Global Climate ◽

The Tibetan Plateau ◽

Lake Surface ◽

Terrestrial Organic Matter ◽

Plant Fossils ◽

History Of ◽

Monsoon System ◽

Uplift History

As an important driver of global climate change during the Cenozoic, the uplift of the Tibetan Plateau (TP) has strongly influenced the origination and evolution of the Asian monsoon system, and therefore the aridification of central Asia. Over the last two decades, the application of stable isotope paleoaltimeters and the discoveries of mammal and plant fossils have greatly promoted the understanding of the uplift history of the TP. However, paleoaltitudinal reconstructions based on different paleoaltimeters have suggested differing outcomes and therefore remain controversial. Novel paleoaltimeters have therefore needed to be developed and applied to constrain the uplift history of the TP more accurately and effectively by comparing and verifying multi-proxies. Paleothermometers based on glyceryl dialkyl glycerol tetraethers (GDGTs) are widely used in terrestrial and ocean temperature reconstructions. In this study, GDGT-based paleothermometers were tentatively applied to the Gyirong Basin on the southern TP, and the Xining Basins on the northern TP, in an attempt to quantitatively reconstruct their paleoaltitudes.Both soil and aquatic-typed branched GDGTs have been identified from Late Miocene to Mid-Pliocene (7.0-3.2 Ma) samples taken from the Gyirong Basin; their reconstructed paleotemperatures were 7.5&#177;3.3&#176;C and 14.2&#177;4.5&#176;C, respectively. The former temperature may represent the mean temperature of the terrestrial organic matter input area, while the latter may represent the lake surface temperature. The results would suggest that the lake surface of the Gyirong Basin during the Late Miocene to Mid-Pliocene was 2.5&#177;0.8 km and that the surrounding mountains exceeded 3.6&#177;0.6 km, implying that the central Himalayas underwent a rapid uplift of ~1.5 km after the Mid-Pliocene.GDGT-based paleotemperature reconstructions using MBT'5ME values show that the Xining Basin dropped in temperature by ~10&#176;C during the ~10.5-8 Ma period, exceeding that in sea surface temperatures and low-altitude terrestrial temperatures during these periods. By combining these results with contemporaneous tectonic and sedimentary records, we infer that these cooling events signaled the regional uplift with the amplitude of ~1 km of the Xining basins. Our results support that the TP was still growing and uplifting substantially since the Late Miocene, which may provide new evidence for understanding the growth, expansion and uplift patterns of the TP.

Download Full-text

Early Eocene rapid exhumation record in the region of Nima, central Tibet, as determined by low-temperature thermochronology

10.5194/egusphere-egu2020-5082 ◽

2020 ◽

Author(s):

Weiwei Xue ◽

Yani Najman ◽

Xiumian Hu ◽

Cristina Persano ◽

Finlay M. Stuart ◽

...

Keyword(s):

Earth Sciences ◽

Tibetan Plateau ◽

Low Temperature ◽

Hanging Wall ◽

Published Data ◽

The Tibetan Plateau ◽

History Of ◽

Central Tibet ◽

Inversion Modelling ◽

Early Paleogene

Knowledge of the geological history of the Tibetan plateau is critical to understanding crustal deformation process, and the plateau&#8217;s influence on climate. However, the timing of Tibetan plateau development remains controversial. The Nima Basin along the Jurassic-Cretaceous Bangong Suture in central Tibet provides well-dated records of exhumation in this area. Here, we present detrital zircon U-Pb, apatite U-Th/He (AHe) and apatite fission track data (AFT) from upper Cretaceous and Oligocene red sandstones and conglomerates in the Nima Basin, as well as from the Xiabie granite in the hanging wall of the basin-bounding Muggar Thrust. 4 granite conglomerate clasts from the above yield zircon U-Pb ages ranging between 114-122 Ma, which likely come from the Xiabie granite. 7 granitoid/sandstone conglomerate clasts yield AHe ages ranging from 21-58 Ma, while AFT ages range from 34-83 Ma. Thermal history inversion modelling for five of the above samples show a consistent rapid cooling from 100 &#8451; to 30 &#8451; between 50-40 Ma, the cooling rate decreased significantly after 40 Ma. Implications of these data, integrated in the context of previously published data for the wider region (e.g. Rohrmann et al. 2012; Haider et al., 2013; Li et al., 2019) will be discussed.&#160;ReferenceRohrmann, A et al., 2012, Thermochronologic evidence for plateau formation in central Tibet by 45 Ma: Geology, v. 40, p. 187-190.Haider, V. L et al., 2013, Cretaceous to Cenozoic evolution of the northern Lhasa Terrane and the Early Paleogene development of peneplains at Nam Co, Tibetan Plateau: Journal of Asian Earth Sciences, v. 70-71, p. 79-98.Li, H. A et al., 2019, The formation and expansion of the eastern Proto-Tibetan Plateau: Insights from low-temperature thermochronology: Journal of Asian Earth Sciences, v. 183, 103975.

Download Full-text

Cenozoic uplift and deformation of the Tibetan Plateau: the geomorphological evidence

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1988.0134 ◽

1988 ◽

Vol 327 (1594) ◽

pp. 365-377 ◽

Cited By ~ 33

Keyword(s):

Tibetan Plateau ◽

Late Miocene ◽

The Tibetan Plateau ◽

Crustal Shortening ◽

Erosion Surface

An erosion surface, interpreted as a pediplain, is traced across the Tibetan Plateau. As a result of faulting and warping, its elevation now varies from approximately 4500-6000m. It was cut across folded and thrust Eocene strata and mid-Miocene granites, but was dislocated by major faults before the Pliocene. Its age is thought to be mid- to late Miocene. Crustal shortening after pediplanation is small. If the crust beneath the Plateau was thickened by deformation during crustal shortening, the thickening must mainly have occurred before the pediplanation.

Download Full-text

THERMOCHRONOLOGIC AND GEOCHRONOLOGIC CONSTRAINTS ON THE TIMING OF CRUSTAL SHORTENING AND THE INITIATION OF LEFT-LATERAL SHEAR WITHIN THE CENTRAL KUNLUN SHAN, NORTHERN TIBET: IMPLICATIONS FOR THE UPLIFT HISTORY OF THE TIBETAN PLATEAU

10.1130/abs/2016am-284498 ◽

2016 ◽

Author(s):

Lydia Staisch ◽

◽

Nathan Niemi ◽

Marin K. Clark ◽

Hong Chang

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Lateral Shear ◽

Crustal Shortening ◽

Northern Tibet ◽

History Of ◽

Uplift History

Download Full-text

Rapid Eocene Exhumation of the West Qinling Belt: Implications for the Growth of the Northeastern Tibetan Plateau

Lithosphere ◽

10.2113/2020/8294751 ◽

2020 ◽

Vol 2020 (1) ◽

Author(s):

Yi-Peng Zhang ◽

Wen-Jun Zheng ◽

Wei-Tao Wang ◽

Yun-Tao Tian ◽

Renjie Zhou ◽

...

Keyword(s):

Tibetan Plateau ◽

Hanging Wall ◽

The Tibetan Plateau ◽

Collision System ◽

The West ◽

Crustal Shortening ◽

Late Mesozoic ◽

West Qinling ◽

Northeastern Tibetan Plateau ◽

Thermal Histories

Abstract Cenozoic exhumation in the northeastern Tibetan Plateau provides insights into spatial-temporal patterns of crustal shortening, erosion, landscape evolution, and geodynamic drivers in the broad India-Eurasia collision system. The NW-SE trending West Qinling Belt has been a central debate as to when crustal shortening took place. Within the West Qinling Belt, a thick succession of Cretaceous sedimentary rocks has been deformed and exhumed along major basin-bounding thrust faults. We present new apatite (U-Th)/He ages from the hanging wall and footwall of this major thrust. Contrasting thermal histories show that rapid cooling commenced as early as ca. 45 Ma and continued for 15–20 Myr for the hanging wall, whereas the footwall experiences continuous cooling and slow exhumation since the late Mesozoic. We infer that accelerated exhumation was driven by thrusting in response to the northward growth of the Tibetan Plateau during the Eocene (ca. 45–35 Ma) based on regional sedimentological, structural, and thermochronological data.

Download Full-text

Late Miocene–Pliocene climate evolution recorded by the red clay cover on the Xiaoshuizi planation surface, NE Tibetan Plateau

Climate of the Past ◽

10.5194/cp-15-405-2019 ◽

2019 ◽

Vol 15 (2) ◽

pp. 405-421 ◽

Cited By ~ 1

Author(s):

Xiaomiao Li ◽

Tingjiang Peng ◽

Zhenhua Ma ◽

Meng Li ◽

Zhantao Feng ◽

...

Keyword(s):

Tibetan Plateau ◽

Late Miocene ◽

Asian Summer Monsoon ◽

Chinese Loess Plateau ◽

The Tibetan Plateau ◽

Red Clay ◽

Climate History ◽

Study Region ◽

Planation Surface ◽

History Of

Abstract. The Pliocene climate and its driving mechanisms have attracted substantial scientific interest because of their potential as an analog for near-future climates. The late Miocene–Pliocene red clay sequence of the main Chinese Loess Plateau (CLP) has been widely used to reconstruct the history of interior Asian aridification and the Asian monsoon. However, red clay sequences deposited on the planation surface of the Tibetan Plateau (TP) are rare. A continuous red clay sequence was recently discovered on the uplifted Xiaoshuizi (XSZ) planation surface in the Maxian Mountains, northeastern (NE) TP. In this study, we analyzed multiple climatic proxies from the XSZ red clay sequence with the aim of reconstructing the late Miocene–early Pliocene climate history of the NE TP and to assess regional climatic differences between the central and western CLP. Our results demonstrate the occurrence of minimal weathering and pedogenesis during the late Miocene, which indicates that the climate was arid. We speculate that precipitation delivered by the paleo East Asian summer monsoon (EASM) was limited during this period and that the intensification of the circulation of the westerlies resulted in arid conditions in the study region. Subsequently, enhanced weathering and pedogenesis occurred intermittently during 4.7–3.9 Ma, which attests to an increase in effective moisture. We ascribe the arid–humid climatic transition near ∼4.7 Ma to the expansion of the paleo-EASM. The warming of the high northern latitudes in response to the closure of the Panama Seaway may have been responsible for the thermodynamical enhancement of the paleo-EASM system, which permitted more moisture to be transported to the NE TP.

Download Full-text