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A geoarchaeological approach to late Quaternary environmental change in South Central TurkeyBoyer, Peter January 1999 (has links)
This thesis adopts a geoarchaeological approach to palaeoenvironmental research in the Konya basin of South-Central Turkey. It involves the analysis of sediment sequencesth rough cultural and alluvial depositsa crossa broad alluvial fan which has developed on the southern edge of the basin since the beginning of the Holocene. Sediments have been analysed by mineral magnetics, particle size, carbonate and organic matter content, and grouping into lithological units has been aided by statistical techniques including principal components analysis and discriminant analysis. Resultso f the analysis have shown a complex sequenceo f deposition across the alluvial fan throughout the Holocene, and within the sequences a number of archaeological sites ranging in date from the Early Neolithic to the Byzantine periods have been identified as being established on various land surfaces. During the early to mid Holocene, the predominant alluvial deposit across the fan was a fine-grained, heavy backswamp clay, deposition of which was time transgressive, i. e. area of deposition changed over this period as the course of the depositing river migrated laterally, and up/down fan. Evidence from the largest and earliest site studied, I; atalh6yiik, where archaeological excavation has recently recommenced, shows that the site was established during the Early Neolithic in an actively flooding alluvial environment. This has implications, not only for the populations inhabiting the site, but also for the wider reasoning behind the establishment of early agricultural settlements in the Near East. Other sites in the area up to the Early Bronze Age have also been seen to have been established in actively depositing alluvial settings. Shortly before c. 4000 BP there was a permanent change in the nature of alluvial deposition, with the heavy backswamp clay being replaced by a less fine-grained deposit of different origin. This initial change was concurrent with an apparent depopulation of the alluvial fan and a relationship between the two phenomena is possible. More importantly, there appear to have been major population changes and increased human influence on the environment of both the fan catchment and the wider region subsequent to these phenomena. Such changes appear to have had a long-term effect on the fan environment as the nature of the alluvial deposition remained relatively unaltered between these events and intensive irrigation schemes which restricted alluvial deposition in the early twentieth century.
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Mineral and Chemical Content of the Deep-Water Sediment Sequences of Bear Lake, Utah-IdahoBiesinger, James C. 01 May 1973 (has links)
Twenty-five piston cores 6 to 12 feet long were obtained from the deepwater sediments of Bear Lake, Utah-Idaho. Analyses of these cores revealed that the deep-water sediments of the lake are divided into two major S('f]Uflnces: a younger sequence rich in carbonate minerals, here called the carbonate sequence, and an older sequence rich in silicate minerals, referred to in this paper as the silt sequence. The carbonate sequence is composed of clay-sized quartz, aragonite, calcite, dolomite, montmorillonite, illite, kaolinite, chlorite, and amorphous material. The silt sequence consists of both silt- sized and claysized particles of quartz, calc ite, dolomite, montmorillonite, illite, kaolinite, chlorite, and amorphous material. Aragonite is absent in the silt sequence. The carbo nate sequence is rich in ostracod exoskeletons and pollen grains. Small quantities of woody material and dark, organic-rich wnes occur within the silt sequence. Chemical analyses for Mg, Ca, Fe, Mn, K, Zn, Na , and Sr were reformed on the sediments. Unusually high concentrations of Fe (8.25 percent) were found in the silt sequence, and of Sr (0 .110 percent), in the carbonate sequence. Isotopic analyses for o18 and c13 in the lake sediments indicate that formation of the authigenic carbonate minerals occurred under normal lake-bottom conditions.
From the data collected, the following conclusions or inferences are made. The carbonate sequence was deposited in water depths similar to, or grea ter than, those of the present. Within this sequence, aragonite is precipitating at present from solution in such quantities that it is responsible for the inversion of the average Ca/ Mg mole ratio of inflowing water of 2:1 to a Ca/ Mg mole ratio of 1:5 in the lake water. The high concentration of Mg +2 and possible high concentration of Sr+2 in the lake water have resulted in conditions favorable for development of protodolomite. Atypical X-ray diffraction patterns for calcite and dolomite, and the relative abundances of aragonite, calc ite, and dolomite reveal that protodolomite probably is, or has been, forming in Bear Lake.
The silt sequence was deposited in water shallow enough for rooted plants to establish themselves . In this shallow environment detrital sediments rich in kaolinitic clay derived from the· Bear Lake Plateau were altered to sediments rich in montmorillonitic clay and amorphous materials.
The sharp contact between the silt sequence and the overlying carbonate sequence apparently represents abrupt termination of widespread swampy depositional conditions in the Bear Lake graben, caused by flooding, which possibly resulted from the most recent major episode of downfaulting of Bear Lake Valley.
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