Sediment source-to-sink process variations of sandy-muddy transitional beaches and their morphological indications  

作　　者：Shaohua Zhao Feng Cai Hongshuai Qi Jianhui Liu Chao Cao Gen Liu Gang Lei 

机构地区：[1]Laboratory of Ocean and Coast Geology,Third Institute of Oceanography,Ministry of Natural Resources,Xiamen 361005,China [2]Key Laboratory of Marine Ecological Conservation and Restoration,Ministry of Natural Resources,Xiamen 361005,China [3]Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration,Xiamen 361005,China

出　　处：《Acta Oceanologica Sinica》2023年第7期10-24,共15页海洋学报（英文版）

基　　金：The National Natural Science Foundation of China under contract Nos 41930538,42076211 and 42076058;the Scientific Research Foundation of the Third Institute of Oceanography,Ministry of Natural Resources under contract Nos 2022017 and 2019006;the China Postdoctoral Science Foundation under contract No.2019M652248.

摘　　要：The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment source-to-sink process variations of such beaches and their morphological indications.The results show that the clay mineral assemblages of these SMT-Beaches mainly comprise of almost equal illite(~30%),kaolinite(~28%),chlorite(~22%),and smectite(~20%)contents.From the surrounding mountain rivers to the SMT-Beaches,clay mineral assemblages show distinct spatial changes characterized by a large decrease(~40%)in kaolinite,whereas the other three clay minerals present relative increases,especially clear for smectite.The muddy sediment sources of SMT-Beaches inferred from the clay mineralogy are mainly derived from nearby mountain rivers coupled with long-distance transport and penetration of the Changjiang River.The sandy sediments of these beaches are predominantly sourced from nearby mountain rivers,the weathering products of surrounding rocks in both mainland and island environments,and erosion of the“Old Red Sand”and“Red Soil Platform”.However,the sandy sediment sources of the SMT-Beaches are largely reduced because of the remarkable decrease in the river fluvial supply associated with intensive human activities such as dam construction and coastal reclamation.Subsequently,the sandy sections of SMT-Beaches present clear erosion and have revealed by both time series remote sensing images and a compilation of published literature.In contrast,the muddy sediment supply of SMT-Beaches is temporarily stable and relatively constant,resulting in the landward migration of the mudflats with relative transgression or accumulation.These findings highlight that the natural evolution processes of SMT-Beaches have been greatly reshaped by intensive human activities.

关 键 词：sandy-muddy transitional beach clay mineral sediment source human activity fluvial discharge morphological evolution 

分 类 号：P737[天文地球—海洋地质]