Anthropogenic filtering of detrital zircon and rutile signals in the Yangtze River
- Author(s)
- Rujun Guo, Xianyan Wang, Xilin Sun, Wencke Wegner, Zengjie Zhang, Yawei Li, Chuanyi Wei, Taorui Zeng, Urs Klötzli, Chang'an Li
- Abstract
Detrital zircon and rutile U-Pb geochronology are widely used to reconstruct sediment provenances, tectonic evolution, and paleo-drainage patterns. However, the impact of anthropogenic dams on sediment transport processes and the resulting bias in provenance signals remains poorly understood. Here, we present an integrated analysis of new rutile grain size (Equivalent Spherical Diameters, ESD) and U-Pb ages data combined with published zircon datasets from the Yangtze River, revealing dam-induced modifications to sediments routing. Our results demonstrate a pronounced grain size partitioning of age distributions: Pre-Cenozoic zircons and rutiles dominate finer-grained fractions (ESD <63 μm), while Cenozoic grains exclusively concentrated in coarser fractions (ESD >63 μm, peaking at 125–250 μm). These younger detrital minerals originate from the distal headwaters of the Jinsha and Dadu Rivers, surviving transport over 3000 km before encountering major dams. Downstream attenuation of Cenozoic zircons is progressive, declining from 9 % at Tuotuohe River and 6 % at Shigu to <1 % at Yibin, with the Three Gorges Dam (TGD) exacerbating this depletion to 0.1 % at Yichang, reflecting a ∼ 95 % loss of the initial input. Similarly, Cenozoic rutiles decrease from 23 % at the Dadu River to below 4 % downstream of the TGD, underscoring its function as a selective filter for coarse metamorphic detritus. Downstream provenance signals show discrete attenuation phases: Cenozoic zircons exhibit abundance reductions at both Yibin (post-Xiluodu Dam) and Yichang (post-TGD), while Dadu-sourced rutiles display single-phase depletion at the TGD. These findings establish that large dams preferentially sequester coarse-grained, young detrital minerals, systematically skewing provenance signatures toward older, finer-grained populations. We conclude that anthropogenic sediment fragmentation through dam trapping induces fundamental biases, necessitating explicit correction in modern provenance studies to prevent erroneous tectonic and paleogeographic interpretations.
- Organisation(s)
- Department of Lithospheric Research
- External organisation(s)
- School of Geography and Ocean Science, Nanjing University, China University of Geosciences, Hubei University, Naturhistorisches Museum Wien (NHM), Sun Yat-sen University, Pingdingshan University, China Earthquake Administration, Chongqing Jiaotong University
- Journal
- Global and Planetary Change
- Volume
- 256
- ISSN
- 0921-8181
- DOI
- https://doi.org/10.1016/j.gloplacha.2025.105185
- Publication date
- 01-2026
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105121 Sedimentology, 105116 Mineralogy, 105101 General geology
- Keywords
- ASJC Scopus subject areas
- Oceanography, Global and Planetary Change
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/e8831cfb-270b-44f4-925b-651892a3947c