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.

Values of δ¹⁸O of zircon from the central Sierra Nevada batholith (SNB), California, yield fresh insight into the magmatic evolution and alteration history of this classic convergent margin batholith. Direct comparison of whole-rock and zircon (Zrc) δ¹⁸O provides evidence for modest (0.5‰), but widespread, alteration, which has complicated interpretation in previous whole-rock δ¹⁸O studies. Four discrete belts of δ¹⁸O values are recognized in the central Sierra. A small belt of plutons with relatively low δ¹⁸O(Zrc) values (5·2–6·0‰) intrudes the foothills, with a sharp increase of δ¹⁸O revealing the concealed Foothills Suture; high δ¹⁸O(Zrc) values (7·0–8·5‰) dominate the rest of the western SNB. East of the axis of the Sierra, δ¹⁸O is distinctly lower (6·75–5·75‰), and decreases monotonically to the Sierra Crest. A sharp 1‰ increase of δ¹⁸O in the eastern Sierra reveals a second crustal boundary, with the fourth belt hosted in high-δ¹⁸O North American crust in the White Mountains and Owens and Long Valleys. Correlated O, Sr, and Pb isotope ratios reveal differences in magma generation between the western and eastern Sierra. The western Sierra experienced massive crustal recycling, with substantial melting and mobilization of accreted oceanic and volcanic arc rocks; crustal contamination affects many western SNB plutons. In contrast, the eastern Sierra was dominated by voluminous recycling of the lithospheric mantle and lower crust, with minimal crustal contamination. Batholith-wide shifts in δ¹⁸O occur between pulses of Cretaceous magmatism that may be linked to tectonic reorganizations of magma sources. Within intrusive suites, δ¹⁸O may be unchanged (Tuolumne); increase (Sonora and Whitney); or decrease (Sequoia and John Muir) with time. These trends show stable long-lived sources, or those where recycling and contamination may increase or decrease with time. Overall, δ¹⁸O reveals diverse magma system behavior at a range of scales in the Sierran arc.