Cretaceous coastal mountain building and potential impacts on climate change in East Asia

Crustal thickness and elevation variations control mountain building and climate change at convergent margins. As an archetypal Andean-type convergent margin, eastern Asia preserves voluminous subduction-related magmas ideal for quantifying these processes and their impacts on climate. Here we use Sr/Y and Ce/Y proxies to show that the crust experienced alternating thickening and thinning episodes during the Late Mesozoic. We identify a noticeably thickened (50–55 km) crust associated with tectonic shortening at 120-105 Ma, corresponding to the emergence of a > 2500-m-high coastal mountain range. Using climate modeling, we demonstrate that the mountain uplift changed Asian atmospheric circulation and precipitation patterns, increased inland aridity (~ 15 %), and prompted the eastward desert expansion, contributing significantly to the arid zonal belt across mid- to low-latitude Asia. These findings, compatible with independent geological, geophysical, and climatic observations, have ..., Sr/Y and Ce/Y proxies  Crustal thickness controls the Sr/Y variability of arc magmas by affecting the stabilization of mineral phases, which fractionates Sr (plagioclase) and Y (garnet) (14,21). Sr is compatible and partitions into plagioclase at low pressures (<10 kbar); at high pressures (>12 kbar), Sr becomes incompatible and enters the liquid phase, and plagioclase is less abundant (64). By contrast, Y is incompatible at low pressures and tends to partition into garnet and amphibole at high pressures (19). Consequently, Sr/Y is a qualitative indicator of the pressures (i.e., crustal depths) at which partial melting and crystal fractionation occur (22,23). Chapman et al. (21) suggest that the Sr/Y ratios of intermediate magmas vary with crustal thickness in the North American Cordillera, with larger Sr/Y ratios signifying greater pressures and, hence, crustal thicknesses. Based on large data sets of global arc lavas, Profeta et al. (19) propose Sr/Y and La/Yb empirical correlat..., , **README**

We have submitted (1) Rb/Sr and Sr/Y filtering criteria (**Figure S1.pdf**), (2) filtered geochemical data for intermediate-felsic rocks from South China used for plots of Sr/Y versus calculated crustal thickness (**Supplementary Table S1.xlsx**), (3) filtered geochemical data for mafic rocks from South China used for plots of Ce/Y versus calculated crustal thickness (**Supplementary Table S2.xlsx**), (4) available elevation and crustal thickness data from the Andes (**Supplementary Table S3.xlsx**), (5) geochemical data used for paleoelevation reconstruction of eastern South China in East Asia (**Supplementary Table S4.xlsx**), and (6) dataset of South China magmatic rocks (**Dataset of South China magmatic rocks.xlsx**). (1) is uploaded as Supplemental information file, and (2)-(6) are uploaded as data files. Detailed descriptions are given below.

**Descriptions**

**(1) Rb/Sr and Sr/Y filtering criteria**

(A-C) Rb/Sr versus Sr/Y diagrams for Jurassic to Cretaceous inter...