Himalayan Geology, Vol. 42 (2), 2021, pp. 329-335, Printed in India

Application of strontium-isotope stratigraphy to Ordovician rocks: A case study of the Tarim Basin in the Northwest China

ZHILING TANG

School of Electronic and Information Engineering, Chongqing Radio & TV University, Chongqing, 400052, China

Email: tzhil2000@163.com

Abstract: Sea-level oscillations and tectonic movements have strongly affected Ordovician strata in the Tarim Basin in the Northwest China. However, internal stratigraphic boundaries within the Ordovician are difficult to be identified due to lack of indicative fossils. Accordingly, this study applies the strontium-isotope stratigraphy to core samples from Well M15 in the Tarim Basin using an established Ordovician 87Sr/86Sr-age curve. Ordovician chronostratigraphic boundaries in Well M15 are identified, accompanied by verification of their accuracies using full-bore formation micro-imaging and conventional logging techniques (gamma ray and resistivity). The consistent Sr isotopic evolution in the basin with its global counterpart indicates that the Sr isotopic data of marine carbonates are of global relevance. Strontium-isotope stratigraphy is an effective tool for stratigraphic studies in absence of indicative fossils.

Keywords: Strontium isotopes, Stratigraphic boundaries, Ordovician, Tarim Basin, Northwest China