Detrital zircon geochronology and geochemistry of Jurassic sandstones in the Xiongcun district, southern Lhasa subterrane, Tibet, China: implications for provenance and tectonic setting
- 18 April 2018
- journal article
- research article
- Published by Cambridge University Press (CUP) in Geological Magazine
- Vol. 156 (4), 683-701
- https://doi.org/10.1017/s0016756818000122
Abstract
Jurassic sandstones in the Xiongcun porphyry copper–gold district, southern Lhasa subterrane, Tibet, China were analysed for petrography, major oxides and trace elements, as well as detrital zircon U–Pb and Hf isotopes, to infer their depositional age, provenance, intensity of source-rock palaeo-weathering and depositional tectonic setting. This new information provides important evidence to constrain the tectonic evolution of the southern Lhasa subterrane during the Late Triassic – Jurassic period. The sandstones are exposed in the lower and upper sections of the Xiongcun Formation. Their average modal abundance (Q21F11L68) classifies them as lithic arenite, which is also supported by geochemical studies. The high chemical index of alteration values (77.19–85.36, mean 79.96) and chemical index of weathering values (86.19–95.59, mean 89.98) of the sandstones imply moderate to intensive weathering of the source rock. Discrimination diagrams based on modal abundance, geochemistry and certain elemental ratios indicate that felsic and intermediate igneous rocks constitute the source rocks, probably with a magmatic arc provenance. The detrital zircon ages (161–243 Ma) and εHf(t) values (+10.5 to +16.2) further constrain the sandstone provenance as subduction-related Triassic–Jurassic felsic and intermediate igneous rocks from the southern Lhasa subterrane. A tectonic discrimination method based on geochemical data of the sandstones, as well as detrital zircon ages from sandstones, reveals that the sandstones were most likely deposited in an oceanic island-arc setting. These results support the hypothesis that the tectonic background of the southern Lhasa subterrane was an oceanic island-arc setting, rather than a continental island-arc setting, during the Late Triassic – Jurassic period.Keywords
This publication has 105 references indexed in Scilit:
- Geochemical and Isotopic Signatures of Surficial Sediments from the Western Continental Shelf of India: Inferring Provenance, Weathering, and the Nature of Organic MatterJournal of Sedimentary Research, 2013
- Eocene Neotethyan slab breakoff in southern Tibet inferred from the Linzizong volcanic recordTectonophysics, 2009
- Geochemical and isotopic constraints on the age and origin of the Nidar Ophiolitic Complex, Ladakh, India: Implications for the Neo-Tethyan subduction along the Indus suture zoneTectonophysics, 2008
- Provenance and tectonic setting of Late Proterozoic Buem sandstones of southeastern Ghana: Evidence from geochemistry and detrital modesJournal of African Earth Sciences, 2006
- Archean crustal evolution in the northern Yilgarn Craton: U–Pb and Hf-isotope evidence from detrital zirconsPrecambrian Research, 2004
- Middle Cretaceous back-arc formation and arc evolution along the Asian margin: the Shyok Suture Zone in northern Ladakh (NW Himalaya)Tectonophysics, 2000
- Tectonic setting discrimination in clastic sequences: an example from the Late Proterozoic Erris Group, NW IrelandPrecambrian Research, 1989
- The CIW index: A new chemical index of weatheringSedimentary Geology, 1988
- Rare earth element geochemistry of Australian Paleozoic graywackes and mudrocks: Provenance and tectonic controlSedimentary Geology, 1985
- Classification of Sandstone: Analysis and ProposalThe Journal of Geology, 1971