ORIGIN AND GEODYNAMIC ENVIRONMENT OF TURBIDITE FORMATION IN QUẢNG NINH AREA, EAST BẮC BỘ

ĐẶNG MỸ CUNG¹, NGUYỄN LINH NGỌC², TRỊNH XUÂN HÒA¹, NGUYỄN VĂN TUẤN¹

¹Việt Nam Institute of Geosciences and Mineral Resources
²Ministry of Natural Resources and Environment

Abstract: The Upper Ordivician - Middle Silurian Cô Tô and Tấn Mài Formations in the Quảng Ninh area, East Bắc Bộ, consist mainly of polymictic sandstone, acidic tuffaceous sandstone, tuffaceous silty claystone, cherty claystone, shale, quartz-sericite schist, chlorite-sericite-quartz schist and dark- to black-grey sericite schist. Typical turbidite structure shows that these beds belong to a turbidite formation.

The petrographical, petrogenetic and geochemical characteristics of major elements show that lithological composition of sandstone of the studied formations is generated from orogeny or regenerated orogeny, which is related to geodynamic environment of convergent plate margin in tectonic context of “subduction zone” or “plate collision”. Geochemical characteristics of major elements, trace elements, rare earth elements show that the Cô Tô and Tấn Mài Formations in the Quảng Ninh area were formed in geodynamic environment - tectonic context of active continental margin.