Sedimentology, palaeoecology and palaeoenvironmental evolution of the 1985 Lhasa to Golmud Geotraverse

Abstract

Abstract Vertical and horizontal measurements of almost 30 km of sections were made along the Geotraverse route at 113 localities ranging in age from Ordovician to Tertiary. Over 280 palaeocurrent measurements were taken and 200 thin sections were studied. Ordovician strata occur only in the Kunlun Terrane, w here thick metamorphosed sequences of elastics and carbonates occur. These are tentatively interpreted as platform margin and slope deposits. During Carboniferous times in the Kunlun Terrane transgressive late-Dinantian marine limestones with tropical to subtropical Eurasian reefoidal faunas overlie fluviatile redbeds derived from an unroofed orogenic belt. The Lhasa Terrane contains shelf basin elastics with low -diversity faunas succeeded by thick late Carboniferous/early Permian glacio-marine mixtites deposited by iceberg meltout. Permian carbonate ramp and shelf facies with reefoidal developments occur over both the Lhasa and Qiangtang Terranes, with coal-bearing elastics and fluviatile redbeds also occurring in the latter.