In this study Late Cretaceous stratum in central Iran, Baharestan section in Isfahan area, was evaluated by biozonation and paleobathymetry.?These sediments have 89 meters thick, and strata have been formed of marl an...In this study Late Cretaceous stratum in central Iran, Baharestan section in Isfahan area, was evaluated by biozonation and paleobathymetry.?These sediments have 89 meters thick, and strata have been formed of marl and marl limestone. In order to indicate the ancient depth of Upper Cretaceous at this time, planktonic and benthic foraminifera were studied. The percentage of the total planktonic foraminifera to the whole sample of foraminifera after the removal of indwell benthic foraminifera (%P*) using the formula?D?=?e(3.58718 + (0.03534?×?%P*))?was identified and depth of 200 - 450 meters was achieved for them. In the present investigation, 30 planktonic species of 11 genus have been identified. The Upper Cretaceous deposit was divided to 6 biozones on the basis of planktonic foraminifera which are cosmopolitan and consist of: Biozone 1—Marginotruncana sigali-Dicarinella primitiva?partial range zone;?Biozone 2—Dicarinella concavata?interval zone;?Biozone 3—Dicarinella asymetrica?total range zone;Biozone 4—Globotruncanita elevata?partial range zone;Biozone 5—Globotruncana ventricosa?interval zone;Biozone 6—Radotruncana calcarata?interval zone.?Based on planktonic foraminifera, the Upper Cretaceous sediments in the study area are of the Turonian-Late Campanian ages.展开更多
The early Eocene is a period with very high atmospheric CO2 levels, which receives many interests from climate modelling aspects. To simulate the early Eocene paleoclimate, a realistic reconstruction for land-sea dist...The early Eocene is a period with very high atmospheric CO2 levels, which receives many interests from climate modelling aspects. To simulate the early Eocene paleoclimate, a realistic reconstruction for land-sea distribution, paleotopography and paleobathymetry is the fundamental step. Here, we present global paleogeographic reconstructions for the early Eocene(~55 Ma), based on integrated paleogeographic data set, the plate-tectonic reconstruction software(GPlates) and geographic information system software(ArcGIS). Comparing with previous paleogeographic reconstructions, we improve the reconstructions by incorporating many recent geologic data and data set, including:(1) Better representations of the Tethys Sea,some marginal or inland seas in the East and Southeast Asia, Atlantic and Arctic region, and the Drake Passage and Tasmanian Gateway;(2) integrated paleoelevation data of global high plateaus and mountains, especially the paleotopography of East Asia,and adopting the latest paleotopographic reconstruction data of the Antarctica;and(3) using the latest data set of oceanic crust paleo-age and oceanic sediment thickness to reconstruct the paleobathymetry.展开更多
文摘In this study Late Cretaceous stratum in central Iran, Baharestan section in Isfahan area, was evaluated by biozonation and paleobathymetry.?These sediments have 89 meters thick, and strata have been formed of marl and marl limestone. In order to indicate the ancient depth of Upper Cretaceous at this time, planktonic and benthic foraminifera were studied. The percentage of the total planktonic foraminifera to the whole sample of foraminifera after the removal of indwell benthic foraminifera (%P*) using the formula?D?=?e(3.58718 + (0.03534?×?%P*))?was identified and depth of 200 - 450 meters was achieved for them. In the present investigation, 30 planktonic species of 11 genus have been identified. The Upper Cretaceous deposit was divided to 6 biozones on the basis of planktonic foraminifera which are cosmopolitan and consist of: Biozone 1—Marginotruncana sigali-Dicarinella primitiva?partial range zone;?Biozone 2—Dicarinella concavata?interval zone;?Biozone 3—Dicarinella asymetrica?total range zone;Biozone 4—Globotruncanita elevata?partial range zone;Biozone 5—Globotruncana ventricosa?interval zone;Biozone 6—Radotruncana calcarata?interval zone.?Based on planktonic foraminifera, the Upper Cretaceous sediments in the study area are of the Turonian-Late Campanian ages.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41690114, 41888101 & 41430531)
文摘The early Eocene is a period with very high atmospheric CO2 levels, which receives many interests from climate modelling aspects. To simulate the early Eocene paleoclimate, a realistic reconstruction for land-sea distribution, paleotopography and paleobathymetry is the fundamental step. Here, we present global paleogeographic reconstructions for the early Eocene(~55 Ma), based on integrated paleogeographic data set, the plate-tectonic reconstruction software(GPlates) and geographic information system software(ArcGIS). Comparing with previous paleogeographic reconstructions, we improve the reconstructions by incorporating many recent geologic data and data set, including:(1) Better representations of the Tethys Sea,some marginal or inland seas in the East and Southeast Asia, Atlantic and Arctic region, and the Drake Passage and Tasmanian Gateway;(2) integrated paleoelevation data of global high plateaus and mountains, especially the paleotopography of East Asia,and adopting the latest paleotopographic reconstruction data of the Antarctica;and(3) using the latest data set of oceanic crust paleo-age and oceanic sediment thickness to reconstruct the paleobathymetry.
