Author:
HUGHES NIGEL C.,MYROW PAUL M.,MCKENZIE N. RYAN,HARPER D. A. T.,BHARGAVA O. N.,TANGRI S. K.,GHALLEY K. S.,FANNING C. M.
Abstract
AbstractThe Pele La Group in the Wachi La section in the Black Mountains of central Bhutan represents the easternmost exposure of Cambrian strata known in the Himalaya. The group contains a succession of siliciclastic rocks with minor amounts of carbonate, the uppermost unit of which, the Quartzite Formation, bears age-diagnostic trilobite body fossils that are approximately 493 Ma old. Trilobite species includeKaolishania granulosa, Taipaikia glabraand the new speciesLingyuanaspis sangae.A billingsellid brachiopod,Billingsellacf.tonkiniana, is co-occurrent. This fauna is precisely correlated with that of a specific stratigraphic horizon within the upper part of theKaolishaniaZone, Stage 9 of the Cambrian System, Furongian Epoch of the North China block, and thus represents the youngest Cambrian sedimentary rocks yet known from the Himalaya. The faunal similarity suggests proximity between North China and the Himalayan margin at this time. This unit was deposited in a predominantly storm-influenced shelf and shoreface environment. U–Pb geochronological data from detrital zircon grains from the fossil-bearing beds of the Quartzite Formation and strata of the underlying Deshichiling Formation show grain age spectra consistent with those from Cambrian rocks of the Lesser and Tethyan Himalaya in Tibet, India and Pakistan. These data support continuity of the northern Gondwanan margin across the Himalaya. Prominent peaks of approximately 500 Ma zircons in both the Quartzite and Deshichiling formations are consistent with the Furongian (late Cambrian) age assignment for these strata. The presence of these relatively young zircon populations implies rapid post-cooling erosion of igneous bodies and subsequent deposition which may reflect the influence of a widespread Cambro-Ordovician orogenic event evident in the western Himalaya.
Publisher
Cambridge University Press (CUP)
Reference137 articles.
1. Cenozoic tectonic evolution of the Himalayan orogen as constrained by along-strike variation of structural geometry, exhumation history, and foreland sedimentation
2. Geyer G. & Uchman A. 1995. Ichnofossil assemblages from the Nama Group (Neoproterozoic–Lower Cambrian) in Namibia and the Precambrian–Cambrian boundary problem revisited. In Morocco ’95, The Lower–Middle Cambrian Standard of Western Gondwana (eds Geyer G. & Landing E. ), pp. 175–202. Beringeria Special Issue 2.
3. Correlation of lithotectonic units across the eastern Himalaya, Bhutan
Cited by
67 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献