Towards interactive global paleogeographic maps, new reconstructions at 60, 40 and 20 Ma

Abstract

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Eccentricity-paced monsoon variability on the northeastern Tibetan Plateau in the Late Oligocene high CO 2 world

“…Temporal and spatial distributions of carbonate δ 18 O and δ 13 C across Asia support the notion that, during the Oligocene, regional moisture in the Lanzhou Basin was predominantly transported by the Asian summer monsoon from the western Pacific and Northern Indian Oceans, with a smaller additional winter moisture transport by the westerlies from the shallow proto-Paratethys Sea ( 25 ), which was located to the west of the Tibetan Plateau ( Fig. 1A ) ( 26 ). Thus, the high-resolution Rb/Sr and χ lf records from the Lanzhou Basin, which reflect regional pedogenesis and magnetic mineral transport, were predominantly controlled by changes in summer monsoon precipitation on orbital time scales.…”

“…which was located to the west of the Tibetan Plateau (Fig. 1A) (26). Thus, the high-resolution Rb/Sr and  lf records from the Lanzhou Basin, which reflect regional pedogenesis and magnetic mineral transport, were predominantly controlled by changes in summer monsoon precipitation on orbital time scales.…”

“… ( A ) Topographic map of Asia with schematic summer monsoon, westerlies, and summer intertropical convergence zone (ITCZ) at present ( 11 ) and with the Late Oligocene proto-Paratethys Sea that was located west of the Tibetan Plateau ( 26 ). ( B ) Topographic map of the Lanzhou Basin and surrounding mountains with the location of the studied Duitinggou section (red solid circle).…”

Miocene high elevation in the Central Alps

“…For instance, the sensitivity of δ 18 O w to regional, global, and topographic variations in paleotemperature, environmental conditions of an air mass prior to orographic ascent, evapotranspiration, water vapor recycling, and changes in vapor source has been shown to introduce uncertainties in stable-isotopebased elevation reconstructions (e.g., Mulch, 2016;Botsyun et al, 2020, Botsyun andEhlers 2021). In particular, isotopic changes over continental Europe could be related to a variety of factors such as declining pCO 2 levels (Pagani et al, 1999), variable ocean circulation and sea surface temperatures (Flower and Kennett, 1994;Wright et al, 1992), sea-level fluctuations (Foster and Rohling, 2013), paleogeographic changes (Herold et al, 2008;Poblete et al, 2021), and other processes affecting δ 18 O w (Botsyun et al, 2019;Poulsen et al, 2007;Risi et al, 2008;Roe et al, 2016;Sewall and Fricke, 2013;Sturm et al, 2010). We thus compare our newly refined near-sea-level δ 18 O estimate with paleoclimate simulations from the isotope-enabled ECHAM5-wiso atmospheric general circulation model (iGCM), which predicts changes in δ 18 O of precipitation.…”

Existence of a continental-scale river system in eastern Tibet during the late Cretaceous–early Palaeogene

“…Although some studies inferred that paleoseawater likely originated from the northwest (e.g., the proto-Paratethys Sea; Wang et al 49 ), this recharge model cannot explain the observation that late Cretaceous marine deposits were absent between the Qiangtang and the Simao-Khorat Basins 47 . Rather, the pronounced southward thickening trends of the evaporite marker intervals 50 , together with the terrestrial palaeogeographic reconstruction of East Asia spanning the late Cretaceous-early Palaeogene transition (e.g., Poblete et al 51 ) likely argue for a transgression of the Neo-Tethyan Ocean from the south or southwest (e.g., refs. 48,50 ).…”