Oligocene‐Miocene Great Lakes in the India‐Asia Collision Zone

Abstract

The Himalayan-Tibetan Plateau is Earth's highest topographic feature, and formed largely during Cenozoic time as India collided with and subducted beneath southern Asia. The >1300 km long, late Oligocene-early Miocene Kailas basin formed within the collisional suture zone more than 35 Ma after the onset of collision, and provides a detailed picture of surface environments, processes and possible geodynamic mechanisms operating within the suture zone during the ongoing convergence of India and Asia. We present new geochronological, sedimentological, organic geochemical and palaeontological data from a previously undocumented 400 km long portion of the Kailas basin. The new data demonstrate that this part of the basin was partly occupied by large, deep, probably meromictic lakes surrounded by coal-forming swamps. Lacustrine facies include coarse-and finegrained turbidites, profundal black shales and marginal Gilbert-type deltas. Organic geochemical temperature proxies suggest that palaeolake water was warmer than 25°C, and cyprinid fish fossils indicate an ecology capable of supporting large fish. Our findings demonstrate a brief period of low elevation in the suture zone during Oligocene-Miocene time (26-21 Ma) and call for a geodynamic mechanism capable of producing a long (>1000 km) and narrow basin along the southern edge of the upper, Asian plate, long after the onset of intercontinental collision. Kailas basin deposits presently are exposed at elevations >6000 m, requiring dramatic elevation gain in the region after Kailas deposition, without strongly shortening the upper crust. Episodic Indian slab rollback, followed by break-off and subsequent renewal of flat-slab subduction, can account for features of the Kailas basin.

Paleoaltimetry Potentiality of Branched GDGTs From Southern Tibet

“…Paleoaltimetry potentiality of branched GDGTs from southern Tibet. DeCelles et al (2016) demonstrated the potential existence of a brief period of lowaltitude topography in the Kailas Basin Suture Zone on the southern TP during the Oligocene-Miocene (26-21 Ma). Using dD wax and MBT/CBT-MAT indices, which themselves have been employed to produce equivalent paleoaltitude estimates, Hren et al (2010) suggested that the northern Sierra Nevada (California, United States) was a warm (i.e., >6-88C warmer than today), high altitude (>2 km asl), and moderate-relief to lowrelief landscape during the Eocene Climatic Optimum (ECO), and throughout the Early Eocene (52-49 Ma; Hren et al, 2010).…”

“…Geochemistry, Geophysics, Geosystems PUBLICATIONS sediments dating from the Early Eocene (Anderson et al, 2015;DeCelles et al, 2016;Hren et al, 2010; Table 2). Using dD wax and MBT/CBT-MAT indices, which themselves have been employed to produce equivalent paleoaltitude estimates, Hren et al (2010) suggested that the northern Sierra Nevada (California, United States) was a warm (i.e., >6-88C warmer than today), high altitude (>2 km asl), and moderate-relief to lowrelief landscape during the Eocene Climatic Optimum (ECO), and throughout the Early Eocene (52-49 Ma; Hren et al, 2010).…”

“…Using dD wax and MBT/CBT-MAT indices, which themselves have been employed to produce equivalent paleoaltitude estimates, Hren et al (2010) suggested that the northern Sierra Nevada (California, United States) was a warm (i.e., >6-88C warmer than today), high altitude (>2 km asl), and moderate-relief to lowrelief landscape during the Eocene Climatic Optimum (ECO), and throughout the Early Eocene (52-49 Ma; Hren et al, 2010). DeCelles et al (2016) demonstrated the potential existence of a brief period of lowaltitude topography in the Kailas Basin Suture Zone on the southern TP during the Oligocene-Miocene (26-21 Ma). The MBT 0 /CBT proxy shows a more gradual cooling trend (and 1.0 km of altitudinal gain) from 7.6 Ma to the present than during the most recent rapid uplift of the Miocene-Pliocene (6-3 Ma) in the Eastern Cordillera in the tropical northern Andes of Colombia (Anderson et al, 2015).…”

A Late Miocene Terrestrial Temperature History for the Northeastern Tibetan Plateau's Period of Tectonic Expansion

“…However, high‐quality quantitative data remain scarce, due to the lack of terrestrial paleotemperature reconstruction tools and well‐dated continuous stratigraphic sequences. Microbial‐branched glycerol dialkyl glycerol tetraether (brGDGT) paleotemperature proxies, in the form of the MBT (MBT′)/CBT ratios, have been developed (Weijers et al, ) over the past decade and have been widely used to reconstruct terrestrial paleotemperatures (e.g., Donders et al, ; Weijers et al, ) and paleoaltitudes (Anderson et al, ; DeCelles et al, ; Deng & Jia, ; Hren et al, ; Zhuang et al, ). However, these proxies are affected greatly by alkalinity and aridity (Bai et al, ; Dirghangi et al, ; H. Wang et al, ; H. Yang et al, ).…”

Gangdese culmination model: Oligocene–Miocene duplexing along the India-Asia suture zone, Lazi region, southern Tibet

“…Along the southern flank of the Gangdese Mountains (Fig. 1), an Oligocene-Miocene, conglomerate-rich, continental unit, referred to as the Kailas (Gangrinboche) Formation, is exposed in buttress unconformity atop Gangdese arc rocks (Gansser, 1964;Aitchison et al, 2002;DeCelles et al, 2011DeCelles et al, , 2016Leary et al, 2016b). Nonmarine strata of similar composition and structural position are continuous, with some variations in sedimentary facies, for over 1300 km along the Yarlung suture zone (Leary et al, 2016b).…”