New insights into the provenance of Cenozoic strata in the Qaidam Basin, northern Tibet: Constraints from combined U-Pb dating of detrital zircons in recent and ancient fluvial sediments

Provenance Analysis of the Paleogene Strata in the Northern Qaidam Basin, China: Evidences from Sediment Distribution, Heavy Mineral Assemblages and Detrital Zircon U‒Pb Geochronology

“…The plane distribution of sedimentary facies, presented by transition of the alluvial fans at basin margin to alluvial plain and lacustrine toward the basin interior, also suggests that sediments are delivered away from these mountains [49]. The published paleocurrent data observed from the Jls (southwest-directed flow [3]; named as Lake Mahai in Zhuang et al, 2011 [3]), Lulehe (southwest-directed flow [3]), and Dahonggou outcrops (southwest-or southeast-directed flow [4,12,50]) agree with delivery pathways of sediments from the Saishiteng Mountains and the Qilian Mountains. Isopach map shows that some local depocenters with relatively high NTG are developed close to basin margin and thin toward basin interior (Figure 3a).…”

“…However, the detrital zircon age spectrum of sample Xx1d-s mainly consist of the early to middle Paleozoic ages and the nearly equivalent late Paleozoic to early Mesozoic ages (Figure 6d) and implies that sample Xx1d-s should have a different provenance. Though the Permian plutonic terranes are exposed in both the central part of the Altyn Tagh Range (Figure 1) [9,31] and the western Saishiteng Mountains (Figure 1c) [9,12], the distinctive heavy mineral assemblages of Xx1d-s, the NTG ratios, and conglomerate percentages tends to support provenance from the Saishiteng Mountains.…”

“…The presence and absence of the late Paleozoic to early Mesozoic age group has been used as important evidence to infer provenance [4,12,13]. When the late Paleozoic to early Mesozoic zircons are presented as a major peak in age spectra of clastic rocks, the Qilian Mountains, in which the Permian-Triassic plutonic terranes are rarely exposed, is commonly excluded from the provenances in previous works [12,13]. However, the late Paleozoic and Mesozoic sedimentary strata are widely distributed in the Qilian Mountains and can supply considerable the late Paleozoic to early Mesozoic zircons [11,37].…”

“…Numerous approaches have been applied to provenance analysis in the Qaidam Basin, including clast composition of conglomerate [1][2][3], sandstone modal analysis [4][5][6][7], detrital mineral U-Pb geochronology [8][9][10][11][12][13], paleocurrent analysis [3,4,[10][11][12][13], heavy mineral analysis [4,5,[14][15][16], and element geochemistry [7,17], etc. However, some discrepancies still exist in previous results of provenance analysis.…”

“…in the Dahonggou area. Song et al (2019) [12] pointed out the Altyn Tagh range was the provenance of the upper Lulehe, Xiganchaigou, and lower Shangganchaigou Fms. in the Dahonggou area.…”