Sequence stratigraphy and evolution of quaternary sediments and related solid mineral resources in coastal zone of Deo Ngang to Deo Hai Van region

Abstract

      The  sequence stratigraphy and evolution of Quaternary sediments in the Deo Ngang to Deo Hai Van coastal zone have been studied for the first time. Based on the sequence stratigraphic model proposed by Tran Nghi (2012), the Binh-Tri-Thien coastal zone has 5 sequences that evoluted cyclically from bottom up corresponding to 5 glacial/interglacial cycles: (1) sequence 1: Early Pleistocene (Q₁¹); (2) Sequence 2: Early middle Pleistocene  (Q₁^2a), (3) Sequence 3: Late middle Pleistocene (Q₁^2b); (4) Sequence 4: Early late Pleistocene (Q₁^3a); (5) Sequence 5: Late late Pleistocene to Holocene (Q₁^3b-Q₂). Each sequence has 3 sedimentary systems tract from the bottom up. Each sedimentary systems tract corresponds to a facies complex: (1) The lowstand systems tract (LST) corresponds to the aluvial muddy  sand facies complex (S_maLST) and the dune sand facies complex (SmvLST); (2) The transgressive systems tract (TST) corresponds to the coastal sandy mud facies complex and the bay mud facies complex (M_sab,bTST) and the coastal sandy barrier bar sand facies (SmTST); (3) The highstand systems tract (HST) corresponds with the alluvial-bay sand facies complex (M_sabHST) and sand dune facies (SmvHST). Sedimentary evolution is shown by an increase in the maturity coefficient (Mt) of sand from 0,2 (sequence1) to 0,8 (sequence 5).