Late Cretaceous aeolian desert system within the Mesozoic fold belt of South China: Palaeoclimatic changes and tectonic forcing of East Asian erg development and preservation

Abstract

This study recognises and identifies the Late Cretaceous aeolian desert system from the Jianshi Basin, located in the intra-continental orogen within the Yangtze Block, South China. Erg deposits comprise aeolian dunes and dry aeolian sandsheets with alluvial facies associations at the margin and show an alluvial-aeolian depositional system. Palaeowind reconstruction of aeolian dune foresets showed that the dominant prevailing winds were westerlies, followed by northeasterlies and subordinate northwesterlies and southeasterlies. It is possible that monsoon rains recharged the water inflow system and caused the development of fluvial sand bodies at the margin of the Jianshi desert during the early deposition stage. The alluvial deposits in the study area were related to regional tectonism, while the dry aeolian system was dominated by mid- and low-latitudinal subtropical highs and the monsoonal climate. Orogenic topography, combined with planetary-scale subtropical high-pressure systems, blocked the transport of moisture, enclosed the low-lying land, and led to the aridification and development of desert depositional systems in the East Asian interior. Moreover, fault-controlled subsidence provided accommodation space in desert basins for alluvial and aeolian deposits. Based on the results obtained from palaeowind reconstructions, the divergent axis of subtropical highs during the Late Cretaceous was located in mid- and low-latitude areas of the Jianshi, Jianghan, Xinjiang, and Hengyang basins in South China. The relatively scattered nature of palaeowinds in the Jianshi Basin and adjacent deserts may indicate a seasonal drift in the divergent axis under the influence of a monsoonal climate.