Sedimentary Model of Fine-Grained Dryland Meandering River Terminus Systems in a Semi-Arid or Arid Endorheic~Basin

Understanding sedimentary features and establishing accurate sedimentary models play an important role in deciphering sedimentary environments of ancient sedimentary rocks as well as establishing sedimentary architecture models of hydrocarbon reservoirs. This study reviews the theoretic development of dryland fluvial systems in arid endorheic basins and recent results of modern Bolivian R'o Colorado River meandering river terminus system.On the low-gradient coastal regions dryland river terminus systems are generally characterized by only one active meandering channel with a downstream reduction in cross-sectional area while other channels are abandoned and completely (or partially) filled. This study also points out controls on channel morphology in the dryland meandering river terminus systems. Infrequent but high magnitude thunderstorm-induced floods enhanceriver bank bleaches, whereby abundance of crevasse splays are triggered along the channel and amalgamations of crevasse splays lead to‘sheet sand’ on floodplain. Avulsions are generally initiated as crevasse channels andnew river channels cut through or superimpose on previous channels over time forming an apparently distributive pattern. In addition, this study proposes the sedimentary model of fine-grained dryland meandering river terminus systems, including channel deposits, overbank deposits and floodplain deposits. Crevasse splays deposits are the majorcomponent of overbank deposits in this meandering river terminus system. Distinctions in terms of sedimentary settings were also discussed between shallow-water deltas and dryland meandering river terminus systems, indicating significant differences in climate and slope for the two sedimentary systems. The proposed sedimentary model of dryland river terminus systems not only complements the current theory of sedimentary systems in endorheic basins, but also helps to accurately characterize hydrocarbon reservoirs as well as provides a new perspective on the exploration and developments of hydrocarbon~resources.