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Climate influences the erosion processes acting at the Earth's surface. However, the effect of cooling during the Late Cenozoic era, including the onset of Pliocene-Pleistocene Northern Hemisphere glaciation (about two to three million years ago), on global erosion rates remains unclear. The uncertainty arises mainly from a lack of consensus on the use of the sedimentary record as a proxy for erosion and the difficulty of isolating the respective contributions of tectonics and climate to erosion. Here we compile 18,000 bedrock thermochronometric ages from around the world and use a formal inversion procedure to estimate temporal and spatial variations in erosion rates. This allows for the quantification of erosion for the source areas that ultimately produce the sediment record on a timescale of millions of years. We find that mountain erosion rates have increased since about six million years ago and most rapidly since two million years ago. The increase of erosion rates is observed at all latitudes, but is most pronounced in glaciated mountain ranges, indicating that glacial processes played an important part. Because mountains represent a considerable fraction of the global production of sediments, our results imply an increase in sediment flux at a global scale that coincides closely with enhanced cooling during the Pliocene and Pleistocene epochs.

The Himalayan crystalline core zone exposed along the Sutlej Valley (India) is composed of two high‐grade metamorphic gneiss sheets that were successively underthrusted and tectonically extruded, as a consequence of the foreland‐directed propagation of crustal deformation in the Indian plate margin. The High Himalayan Crystalline Sequence (HHCS) is composed of amphibolite facies to migmatitic paragneisses, metamorphosed at temperatures up to 750°C at 30 km depth between Eocene and early Miocene. During early Miocene, combined thrusting along the Main Central Thrust (MCT) and extension along the Sangla Detachment induced the rapid exhumation and cooling of the HHCS, whereas exhumation was mainly controlled by erosion since middle Miocene. The Lesser Himalayan Crystalline Sequence (LHCS) is composed of amphibolite facies para‐ and orthogneisses, metamorphosed at temperatures up to 700°C during underthrusting down to 30 km depth beneath the MCT. The LHCS cooled very rapidly since late Miocene, as a consequence of exhumation controlled by thrusting along the Munsiari Thrust and extension in the MCT hanging wall. This renewed phase of tectonic extrusion at the Himalayan front is still active, as indicated by the present‐day regional seismicity, and by hydrothermal circulation linked to elevated near‐surface geothermal gradients in the LHCS. As recently evidenced in the Himalayan syntaxes, active exhumation of deep crustal rocks along the Sutlej Valley is spatially correlated with the high erosional potential of this major trans‐Himalayan river. This correlation supports the emerging view of a positive feedback during continental collision between crustal‐scale tectono‐thermal reworking and efficient erosion along major river systems.

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[1] A range of ages have been proposed for the timing of India-Asia collision; the range to some extent reflects different definitions of collision and methods used to date it. In this paper we discuss three approaches that have been used to constrain the time of collision: the time of cessation of marine facies, the time of the first arrival of Asian detritus on the Indian plate, and the determination of the relative positions of India and Asia through time. In the Qumiba sedimentary section located south of the Yarlung Tsangpo suture in Tibet, a previous work has dated marine facies at middle to late Eocene, by far the youngest marine sediments recorded in the region. By contrast, our biostratigraphic data indicate the youngest marine facies preserved at this locality are 50.6-52.8 Ma, in broad agreement with the timing of cessation of marine facies elsewhere throughout the region. Double dating of detrital zircons from this formation, by U-Pb and fission track methods, indicates an Asian contribution to the rocks thus documenting the time of arrival of Asian material onto the Indian plate at this time and hence constraining the time of India-Asia collision. Our reconstruction of the positions of India and Asia by using a compilation of published palaeomagnetic data indicates initial contact between the continents in the early Eocene. We conclude the paper with a discussion on the viability of a recent assertion that collision between India and Asia could not have occurred prior to ∼35 Ma.

Results from a zircon U-Pb study of the metamorphic basement of Vietnam reveal that a large part of the continental crust was affected by a short-lived episode of ductile deformation and high-temperature metamorphism between 258 ؎ 6 Ma and 243 ؎ 5 Ma. Although coincident with final stages of North-South China collision (Qinling orogenesis), the thermotectonism in Vietnam was caused by accretion of Sibumasu to Indochina-South China. This accretion event (Indosinian orogeny) has regional significance because it contributed to the final stages of North-South China collision, an aspect not explicitly recognized in Qinling orogenic models.

Marine accumulations of terrigenous sediment are widely assumed to accurately record climatic- and tectonic-controlled mountain denudation and play an important role in understanding late Cenozoic mountain uplift and global cooling. Underpinning this is the assumption that the majority of sediment eroded from hinterland orogenic belts is transported to and ultimately stored in marine basins with little lag between erosion and deposition. Here we use a detailed and multi-technique sedimentary provenance dataset from the Yellow River to show that substantial amounts of sediment eroded from Northeast Tibet and carried by the river's upper reach are stored in the Chinese Loess Plateau and the western Mu Us desert. This finding revises our understanding of the origin of the Chinese Loess Plateau and provides a potential solution for mismatches between late Cenozoic terrestrial sedimentation and marine geochemistry records, as well as between global CO2 and erosion records.

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