The uplift of the Tibetan plateau, an area that is 2,000 km wide, to an altitude of about 5,000 m has been shown to modify global climate and to influence monsoon intensity. Mechanical and thermal models for homogeneous thickening of the lithosphere make specific predictions about uplift rates of the Tibetan plateau, but the precise history of the uplift of the plateau has yet to be confirmed by observations. Here we present well-preserved fossil leaf assemblages from the Namling basin, southern Tibet, dated to approximately 15 Myr ago, which allow us to reconstruct the temperatures within the basin at that time. Using a numerical general circulation model to estimate moist static energy at the location of the fossil leaves, we reconstruct the elevation of the Namling basin 15 Myr ago to be 4,689 +/- 895 m or 4,638 +/- 847 m, depending on the reference data used. This is comparable to the present-day altitude of 4,600 m. We conclude that the elevation of the southern Tibetan plateau probably has remained unchanged for the past 15 Myr.

Weathering profiles developed on basalt substrate contain information relevant to climate, atmospheric composition and evolution, nutrient release into the hydrosphere, and understanding Martian regolith. In this study, the chemical compositions of two profiles developed on Deccan Trap basalt are examined. One is sub-Recent and has only progressed to a moderate degree of alteration (Chhindwara profile), whereas the other is ancient (Paleocene) and the degree of alteration is extreme (Bidar laterite). In an attempt to better quantify the chemical changes during incipient to intermediate weathering of mafic substrates, we propose a new index: the mafic index of alteration (MIA). Similar to the chemical index of alteration (CIA), the MIA quantifies the net loss of the mobile major elements (Ca, Mg, Na, K ± Fe) relative to the immobile major elements (Al ± Fe). The redox-dependent weathering behaviour of Fe is factored into two separate arrangements of the MIA that apply to oxidative [MIA(O)] or reduced [MIA(R)] weathering. The MIA can be visualised in a variety of ternary diagrams in the Al-Fe-Mg-Ca-Na-K system. To chemically quantify the stages of advanced to extreme weathering, at which the MIA and CIA are ineffective, the SiO2 to (Al2O3+Fe2O3) mass ratio, based on the established Si-Al-Fe (SAF) 'laterite' ternary diagram, is used; we propose that this ratio be referred to as the 'index of lateritisation' (IOL).Major element chemical variations, as expressed by weathering indices, were used to relate the extent of weathering with the behavior of trace elements (alkali, alkaline earth, rare earth, and Nb) in the profiles. During the early stages of basalt weathering, the mobile trace elements (Sr, Be, Li) are anticorrelated with the chemical weathering indices and thus released during these stages. By contrast, the monovalent elements (K, Rb, Cs, Tl), excluding Na and Li, appear to be associated with the pedogenetic clay minerals. Of these elements, those with the closest ionic radii are most closely related. Fractionation of the REE (Sm/Nd, Eu/Eu*, Ce/Ce*) is evident during weathering of the basalt. The loss of Eu is linked with Sr, Ca, and Na and thus plagioclase dissolution during the stages of incipient to intermediate weathering. The fractionation of Sm/Nd suggests that basaltic weathering products may not always preserve their parent rock ratio and, consequently, their Nd isotope composition over time.Finally, weathering in the sub-Recent profile is shown to have progressed across two lava flows, whose morphology initially controlled the extent of weathering. Certain compositional variations in the original flows (e.g., immobile element ratios) are preserved through the effects of chemical weathering and have the potential to influence mass balance calculations across the entire profile. CHEMGE6928 highlights New chemical weathering index is introduced: the mafic index of alteration (MIA)  Si:(Si+Fe+Al) ratio to quantify advanced weathering (the index of lateritisation)  Separate lava flows in a weathering...

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The 260-million-year-old Emeishan volcanic province of southwest China overlies and is interbedded with Middle Permian carbonates that contain a record of the Guadalupian mass extinction. Sections in the region thus provide an opportunity to directly monitor the relative timing of extinction and volcanism within the same locations. These show that the onset of volcanism was marked by both large phreatomagmatic eruptions and extinctions amongst fusulinacean foraminifers and calcareous algae. The temporal coincidence of these two phenomena supports the idea of a cause-and-effect relationship. The crisis predates the onset of a major negative carbon isotope excursion that points to subsequent severe disturbance of the ocean-atmosphere carbon cycle.

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The Deccan Volcanic Province is one of the world's largest continental flood basalt provinces, and derives additional importance because its eruptions (64–67 Ma) straddle the Cretaceous–Tertiary boundary. To better assess the environmental impact of Deccan volcanism, and its possible effect upon Cretaceous–Tertiary boundary biota, it is necessary to document the stratigraphy, chronology and volume of the eruptions. New chemostratigraphical data permit mapping of the SE Deccan. These data strengthen the likelihood that the Rajahmundry Traps of eastern India were originally fed by long-distance flows, and are an extension of the Main Deccan Volcanic Province. An east–west cross-section reveals a depression or ‘moat’ around the SE periphery of the Deccan Volcanic Province. This provided a site in which shallow lakes initially formed, and along which later lava eruptions became channelled and confined. Published palaeomagnetic data indicate that the lavas of the SE Deccan were erupted during Chron 29R, coeval with the Cretaceous–Tertiary boundary, and the chemostratigraphic data place the associated lake sediments (i.e. Lameta Group) beneath and within lavas of the Wai Subgroup. Finally, these new map data are combined with previous work to provide a quantitative estimate for the original Deccan Volcanic Province eruptive volume of c . 1.3 × 10 6 km 3 .

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