Sedimentology
Sh. Erfan; K. Rezaei; R. Lak; S. M. Ale Ali
Abstract
Lake Urmia is the greatest hayper salin Lake in the world. This Lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meter. Evaluation of past climate change in Lake Urmia, according to Clay Minerals, ...
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Lake Urmia is the greatest hayper salin Lake in the world. This Lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meter. Evaluation of past climate change in Lake Urmia, according to Clay Minerals, is the main subject for current study. For mineralogical and sedimentological investigations 18 sediment cores were collected from the east and west of Urmia lake. 96 samples from 18 sediment cores in transect to the center of lake were collected and studied by X-ray diffraction (XRD) technique. The clay minerals include Kaolinite, Illite and Montmorillonite. Kaolinite and Illite are the most important clay minerals in the Coastal plain of urmia lake. Origins of clay minerals in the Coastal plain of urmia lake are generally detrital, occurred by physical weathering and indicate composition of bed rock. The study of surface sediments indicates that amount of clay minerals from margin to center of the lake such as another detrital mineral (Quartz) is decreased. In addition, amount of them towards depth is increased. Therefore, it shows the presence of a high water level and cold - humid climate in the past (late Pleistocene).
SH Erfan; M.A Hamedi
Abstract
What referred as the MiyankallehPeninsula and the GorganGulf in the southeast of Caspian Sea is in fact a typical barrier island complex consisting of following major environments: 1) open sea, 2) MiyankallehBarrierIsland, and 3) Gorgan Lagoon. The major sub environments of this barrier complex are beach ...
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What referred as the MiyankallehPeninsula and the GorganGulf in the southeast of Caspian Sea is in fact a typical barrier island complex consisting of following major environments: 1) open sea, 2) MiyankallehBarrierIsland, and 3) Gorgan Lagoon. The major sub environments of this barrier complex are beach sand ridges, back barrier salt marsh; fresh water marsh; active, semi active, and stabilized sand dunes; and puffy grounds. The relics of sea- level changing and the major sedimentary structures of this complex are: different kinds of marine and non-marine ripple marks, some kinds of rill marks, swash & backwash, long shore currents & rip currents, mud cracks, parallel and perpendicular beach bars, many traces of faunas on the stoss slope of sand dunes, and small bays. The form and development of the Miyankalleh Barrier Island Complex depend on the presence and combination of several factors such as high sands, high- energy storms, and long shore currents in a micro tidal, high amplitude wave dominated regime in a gentle slope of this beach. The Khozini channel, which was the way of connecting the Gorgan Lagoon to the Caspian Sea was the result of unsuccessful man made channel filled & abandoned quickly by long shore currents of the Caspian Sea. Chemical analysis and core studies of the Zaghmarz region indicate this area was part of the shallow marine Caspian Sea in the past, which subsequently occupied by non-marine sediments. The human interferences caused the intensive geomorphologic changes and converted the depositional bank to the erosional coast in the western part of studied area. This event resulted in retreating of more than 40 meters landwards of this coast and revealed an old wooden ship beneath the six meters beach sand ridges.
