Characteristics and Geological Conditions of Coastal Zone Quaternary Sediment Formations in The Binh -Tri -Thien Area under The Context of Global Sea Level Change

Abstract

Quaternary sediments in the Binh Tri Thien coastal zone are diverse in both material composition and development history. From land to sea, there are 4 structural regions: i) marginal plain region; ii) Coastal lagoon region; iii) Coastal sand dunes region; and iv) Monocline coastal subsidence region. In the vertical direction, all four regions have five sedimentary cycles as follows: a) Early Pleistocene (Q11); b) Early middle Pleistocene (Q12a); c) Late middle Pleistocene (Q12b); d) Early late Pleistocene (Q13a); e) Late late Pleistocene (Q13b-Q2). Four structural zones are characterized by different lithofacies complexes: 1) In the lowstand systems tract (LST) at the beginning of each cycle in all 4 structural zones, the SmaLST facies complex is present; 2) In the transgressive systems tract (TST), there are the following lithofacies complexes: a) region I: MsbTST; b) region II: MlgTST; c) region III: SmTST; d) region IV: Msam,mTST; 3) In the highstand systems tract (HST) there are the following facies complexes: a) Region I: (MsabHST); b) Region II: MslgHST; c) Region III: SmvHST; d) Region IV: SmmHST. The difference in sedimentary facies in the transgressive and highstand systems tract depends on the differentiation of four geological structure regions.