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Clastic sediment composition constitutes a key archive of Earth history, controlled by allogenic and autogenic processes that impact weathering, erosion, sediment transfer, and deposition. Deciphering those processes can provide valuable insights into ancient and modern tectonic, geomorphic, climatic, and anthropogenic controls that shape sediment routing systems over a wide range of temporal and spatial scales. However, in order to clearly identify the controls on sediment composition, it is necessary to exclude sources of bias that may mask or diminish the original provenance signal. Such biases may be natural, including mineral fertility, sediment recycling, and grain size, or analytical. This special collection arises from the fifth meeting of the working group on sediment generation held at the University Milano‐Bicocca in Milan, Italy, from 28 to 30 June 2022. The collation includes studies that investigate biasing factors affecting all steps of the sediment cascade and all stages of sample collection, preparation, and analysis, as well as case studies that aim to disentangle original provenance signals from geological, environmental, or analytical noise. Plain Language Summary: This text introduces the special collection collating contributions arising from the fifth meeting of the working group on sediment generation (WGSG), held at the University Milano‐Bicocca in Milan, Italy, from 28 to 30 June 2022. The WGSG aims at contributing to the understanding of siliciclastic sediment generation. Sediment composition reflects the tectonic, geomorphic, climatic, and anthropogenic characteristics of the Earth surface. Sedimentary successions therefore provide the possibility to interpret ancient Earth surface conditions. The theme of this fifth special collection is the identification and mitigation of natural and analytical bias, that may arise, for example, through the subjective selection of sampling sites or analytical techniques. Bias can create noise, which may prevent the correct interpretation of past Earth surface conditions. The collation includes studies that investigate specific biasing factors, as well as case studies that aim to disentangle original compositional signals from analytical and environmental noise. Key Points: Numerous biasing factors and processes exist that complicate the understanding of source‐to‐sink relationshipsBias is defined as any systematic error that is introduced by selecting specific samples, proxies, or procedures17 papers dealing with natural and methodological/analytical biases are presented [ABSTRACT FROM AUTHOR]

The Yarlung Tsangpo, draining the Himalayan‐Tibetan orogen along the Indus‐Yarlung suture zone, receives detritus from the deformed remnants of both Indian margin to the south and Asian margin to the north. High resolution petrographic, heavy‐mineral and geochemical datasets, combined with published geochronological data, allow us to monitor compositional changes, estimate erosion rates and investigate lithologic, climatic and anthropic controls on sediment fluxes along this large sediment‐routing system entirely developed within high mountain areas. Sediment generated from the Lhasa Block along the southern margin of Asia is characterized by abundant feldspar and volcanic rock fragments, amphibole‐dominated transparent heavy mineral suite and high concentrations of K, Rb, Be, Th and Pb. Himalayan‐derived sand, instead, is characterized by sedimentary to low‐rank metasedimentary rock fragments, poor transparent heavy mineral suite dominated by durable recycled (zircon, tourmaline) or metamorphic minerals (chloritoid, garnet) and high Ca concentration. Sand from the ophiolitic suture is distinguished by serpentinite grains and mafic volcanic or metavolcanic detritus, transparent heavy mineral suite including olivine, Cr‐spinel, enstatite and clinopyroxene, and high Mg, Cr, Ni and low rare earth elements. Himalayan detritus is prominent in Yarlung Tsangpo upper reaches, whereas detritus from the Lhasa Block becomes progressively predominant in the middle and lower reaches. Provenance budgets based on integrated petrographic, heavy‐mineral and geochemical datasets indicate that ca. 83% of the detritus is supplied by the Lhasa Block and the rest mostly from the Himalaya (ca. 12%) and subordinately from the ophiolitic suture (5%). A low average erosion rate of ca. 0.06 mm/a was estimated for the Yarlung Tsangpo catchment upstream of the Namche Barwa syntaxis, which resulted from dry climate, relatively mild average relief and sediment storage in wide valley tracts of the middle and lower reaches. The decrease in sediment flux recorded in recent decades is mainly ascribed to growing human activities, which are becoming a prominent control on sediment generation and transportation even in the high‐mountain area of South Tibet. [ABSTRACT FROM AUTHOR]