This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation（middleelate Devonian） in southcentral Iran ar...This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation（middleelate Devonian） in southcentral Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bahram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments： shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east（Sardar section） and thins in southern locations（Hutk section）. Three 3rdorder cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.展开更多
Surface sediment data acquired by the grab sampling technique were used in the present study to produce a high-resolution and full coverage surface grain-size mapping. The objective is to test whether the hypothetical...Surface sediment data acquired by the grab sampling technique were used in the present study to produce a high-resolution and full coverage surface grain-size mapping. The objective is to test whether the hypothetically natural relationship between the surface sediment distribution and complex bathymetry could be used to improve the quality of surface sediment patches mapping. This is based on our hypothesis that grain-size characteristics of the ridge surface sediments must be intrinsically related to the hydrodynamic condition, i.e. storm-induced currents and the geometry of the seabed morphology. The median grain-size data were obtained from grab samples with inclusive bathymetric point recorded at 713 locations on the high-energy and shallow shelf of the Spiekeroog Barrier Island at the German Bight of the Southern North Sea. The area features two-parallel shoreface-connected ridges which is situated obliquely WNW-SSE oriented and mostly sandy in texture. We made use the median grain-size (d50) as the predictand and the bathymetry as the covariable to produce a high-resolution raster map of median grain-size distribution using the Cokriging interpolation. From the cross-validation of the estimated median grain-size data with the measured ones, it is clear that the gradient of the linear regression line for Cokriging is leaning closer towards the theoretical perfect-correlation line (45°) compared to that for Anisotropy Kriging. The interpolation result with Cokriging shows more realistic estimates on the unknown points of the median grain-size and gave detail to surface sediment patchiness, which spatial scale is more or less in agreement with previous studies. In addition to the moderate correlation obtained from the Pearson correlation (r = 0.44), the cross-variogram shows a more precise nature of their spatial correlation, which is physically meaningful for the interpolation process. The present study partially contributes to the framework of habitat mapping and nature protection that is to fill the gaps 展开更多
基金a part of project of the Hormozgan University and two master theses of the senior author, which is supported by the Department of Geology at Hormozgan University of Bandar Abbas, Iran
文摘This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation（middleelate Devonian） in southcentral Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bahram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments： shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east（Sardar section） and thins in southern locations（Hutk section）. Three 3rdorder cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.
文摘Surface sediment data acquired by the grab sampling technique were used in the present study to produce a high-resolution and full coverage surface grain-size mapping. The objective is to test whether the hypothetically natural relationship between the surface sediment distribution and complex bathymetry could be used to improve the quality of surface sediment patches mapping. This is based on our hypothesis that grain-size characteristics of the ridge surface sediments must be intrinsically related to the hydrodynamic condition, i.e. storm-induced currents and the geometry of the seabed morphology. The median grain-size data were obtained from grab samples with inclusive bathymetric point recorded at 713 locations on the high-energy and shallow shelf of the Spiekeroog Barrier Island at the German Bight of the Southern North Sea. The area features two-parallel shoreface-connected ridges which is situated obliquely WNW-SSE oriented and mostly sandy in texture. We made use the median grain-size (d50) as the predictand and the bathymetry as the covariable to produce a high-resolution raster map of median grain-size distribution using the Cokriging interpolation. From the cross-validation of the estimated median grain-size data with the measured ones, it is clear that the gradient of the linear regression line for Cokriging is leaning closer towards the theoretical perfect-correlation line (45°) compared to that for Anisotropy Kriging. The interpolation result with Cokriging shows more realistic estimates on the unknown points of the median grain-size and gave detail to surface sediment patchiness, which spatial scale is more or less in agreement with previous studies. In addition to the moderate correlation obtained from the Pearson correlation (r = 0.44), the cross-variogram shows a more precise nature of their spatial correlation, which is physically meaningful for the interpolation process. The present study partially contributes to the framework of habitat mapping and nature protection that is to fill the gaps
