Facies Analysis of the Neogene Delta of the Amur River, Sakhalin, Russian Far East: Controls on Sand Distribution
Clare Davies, Sarah Poynter, David Macdonald, Rachel Flecker, Larisa Voronova, Vladimir Galverson, Pavel Kovtunovich, Lidiya Fot’yanova, Eric Blanc, 2005. "Facies Analysis of the Neogene Delta of the Amur River, Sakhalin, Russian Far East: Controls on Sand Distribution", River Deltas–Concepts, Models, and Examples, Liviu Giosan, Janok P. Bhattacharya
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Miocene-Pliocene sediments in the northern part of Sakhalin, in the Russian Far East, contain substantial hydrocarbon reservoirs and are the target of further exploration. These sandstones are well sorted and have been interpreted as the deltaic deposits of the paleo-Amur River, sourced from the Russian mainland. Despite their economic importance, no facies interpretation of the sediments from the onshore sections, nor the paleogeographic evolution of the delta through the Neogene, have previously been published.
From outcrop we have identified nine facies associations recording deposition in delta-top, beach, delta-front, transitional, and offshore marine settings. The distribution of these facies associations through time indicates that the paleo-Amur delta prograded east across Sakhalin in two major episodes: first in the Early-Middle Miocene and later in the Late Miocene-Pliocene. These delta-top to delta-front sandstone deposition events are separated by a more mud-rich episode. To the east, limited terrigenous supply resulted in accumulation of biosiliceous sediments. Paleogeographic reconstructions show that the distribution of sand and biosiliceous marine sediment was probably controlled by a combination of tectonic configuration and persistent patterns of longshore currents.
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Deltas are amongst the most environmentally and economically important coastal sedimentary environments. Studies of deltas lag behind research in both fluvial and deep-water depositional systems, as well as more geomorphologically oriented land studies. This knowledge lag reflects both a reorientation of the petroleum industry in the last two decades toward deep-water systems, as well as the difficulty of working across the shoreline with the traditional tools used for oceanographic or land-based work. However, deltaic studies are experiencing a renewed focus, because of their global importance in environmental and other societal concerns. This volume stems from a special session: Deltas: Old and New, held at the Annual Geological Society of America conference in October 2002, that was convened to highlight these new directions in deltaic research.