Microbial and Geochronologic Constraints on the Neogene Paleotopography of Northern Tibetan Plateau

Abstract

High topography is the manifestation of the balance between deep and surficial erosional processes. Hence, reconstructions of paleotopography are critical for disentangling records of orogenesis and climate. Here we used a new approach by combining detrital zircon U‐Pb geochronology and tetraether‐based paleothermometry to characterize the Neogene paleotopography of Northern Tibetan Plateau. Detrital zircon U‐Pb data reveal that the Qilian Shan has been uplifted, providing sediments to bounding basins since circa 15.8 Ma. The paleothermometry studies show warm temperatures for paleosols (<12.4–9.5 Ma and 3.7–2.0 Ma) and low temperatures for lacustrine facies (12.4 Ma and 9.5–3.7 Ma). We interpret the different temperatures to reflect the in situ production of tetraethers under warm temperatures within the basin (paleosols) versus terrestrial inputs from high and cold drainage to the paleolake (lacustrine facies). The study supports a topography with significant relief in the Northern Tibetan Plateau since 12.4 Ma.

Organic Molecular Paleohypsometry: A New Approach to Quantifying Paleotopography and Paleorelief

“…These generally rely on environmental variables that are related to elevation such as temperature (Quade et al, 2013;Quade et al, 2007), pressure (Sahagian and Maus, 1994;Sahagian et al, 2002;Sahagian and Proussevitch, 2007), plant physiology (Wolfe et al, 1997;Forest et al, 1999), or water isotopes (Garzione et al, 2000;Poage and Chamberlain, 2001;Poage and Chamberlain, 2002;Rowley and Garzione, 2007;Hren et al, 2009). Over the past several decades, stable isotope paleoaltimetry has become one of the most commonly utilized paleoelevation techniques (e.g., Huntington et al, 2015;Wheeler et al, 2016;Fan et al, 2017;Tang et al, 2017;Bershaw et al, 2019;Li et al, 2019;Zhuang et al, 2019). This is due in part, to the abundance of materials that preserve the isotopic signature of ambient water such as carbonates and clays (Chamberlain and Poage, 2000;Sjostrom et al, 2006;, volcanic glasses (Cassel et al, 2009;Bershaw et al, 2019;, fossils (Kohn et al, 2002), and leaf waxes (Polissar et al, 2009;Hren et al, 2010;Anderson et al, 2015;Zhuang et al, 2019).…”

“…Over the past several decades, stable isotope paleoaltimetry has become one of the most commonly utilized paleoelevation techniques (e.g., Huntington et al, 2015;Wheeler et al, 2016;Fan et al, 2017;Tang et al, 2017;Bershaw et al, 2019;Li et al, 2019;Zhuang et al, 2019). This is due in part, to the abundance of materials that preserve the isotopic signature of ambient water such as carbonates and clays (Chamberlain and Poage, 2000;Sjostrom et al, 2006;, volcanic glasses (Cassel et al, 2009;Bershaw et al, 2019;, fossils (Kohn et al, 2002), and leaf waxes (Polissar et al, 2009;Hren et al, 2010;Anderson et al, 2015;Zhuang et al, 2019). Application of stable isotope-based approaches has provided fundamental insight into how Cordilleran orogens evolve (Fan et al, 2017;Feng et al, 2013;Kent-Corson et al, 2006;Andreas Mulch and Chamberlain, 2007), long-timescale changes in the elevation of orogenic plateaus (Dettman et al, 2003;Ghosh et al, 2006;Molnar et al, 2006;Rowley and Currie, 2006;Hoke et al, 2014;Currie et al, 2016), even the role of tectonic change on biological diversification (Phillips et al, 2013).…”

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, ).…”

Late Oligocene Tectonic Uplift of the East Kunlun Shan: Expansion of the Northeastern Tibetan Plateau

“…The deforming viscous lithospheric mantle model (Clark, 2012) predicts that the Paleocene to Eocene deformation built a relatively stable northeastern plateau boundary. Yet, recent data from sedimentology, thermochronology, and micropaleontology point to widespread middle‐late Miocene tectonic events in the northeastern Tibetan Plateau (e.g., Bovet et al., 2009; Pang et al., 2019; Yu et al., 2019; Zhuang et al., 2019), implying synchronous deformation during the late Cenozoic.…”