کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6349191 1622134 2016 49 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Paleoenvironmental reconstruction of the Late Santonian Songliao Paleo-lake
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Paleoenvironmental reconstruction of the Late Santonian Songliao Paleo-lake
چکیده انگلیسی
The Late Cretaceous is often characterized as having a variable greenhouse climate, however, the relatively few continental sites preserving geologic records from this time exist limiting information on terrestrial climate and environments. Worldwide, the Songliao Basin (SLB) of northeastern China is one of the largest Cretaceous-age continental rift basins. Thus, this well-preserved lacustrine deposit provides a unique record of terrestrial paleoenvironmental conditions during the Cretaceous. Here, we report organic geochemical data from Late Cretaceous-age lacustrine deposits (lower Nenjiang Formation) from the eastern side of the SLB. Outcrop samples were collected from the Houjingou section and the following analyses were performed: (1) total organic carbon (TOC) content and isotopic composition, (2) biomarker distribution, including the identification and determination of relative amounts of both aliphatic and aromatic hydrocarbons and steranes, and (3) compound specific stable carbon and hydrogen isotopic compositions of n-alkanes. The biomarker distribution and stable carbon isotopic values (δ13C) of the TOC indicate organic matter (OM) from the uppermost section of the first member of the Nenjiang Formation (Upper K2n1) was mainly sourced from aquatic macrophytes and land plants. In the lower part of the second member of the Nenjiang Formation (Lower K2n2) the biomarker distribution and δ13C of both the TOC and n-alkanes indicate that OM was sourced from a mixture of algae, bacteria, and higher plants. As a result of marine transgression, seawater incursions, indicated by the presence of 24-n-propyl-cholestanes and 24-iso-propyl-cholestanes, occurred episodically in Lower K2n2. The negative hydrogen isotopic composition (δ2H) of short chain n-alkanes in Lower K2n2 indicates an extremely humid environment and it is likely that an influx of freshwater caused large-scale flooding of the Songliao Paleo-lake. High-resolution biomarker and stable isotope records from the Houjingou section demonstrate abrupt environmental changes in the Songliao Paleo-lake following seawater incursions during the Late Cretaceous.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Palaeogeography, Palaeoclimatology, Palaeoecology - Volume 457, 1 September 2016, Pages 290-303
نویسندگان
, , , , , , ,