کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4749276 | 1642212 | 2009 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Evidence of increasing surface water oligotrophy during the Campanian-Maastrichtian boundary interval: Calcareous nannofossils from DSDP Hole 390A (Blake Nose)
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فسیل شناسی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Evidence of increasing surface water oligotrophy during the Campanian-Maastrichtian boundary interval: Calcareous nannofossils from DSDP Hole 390A (Blake Nose) Evidence of increasing surface water oligotrophy during the Campanian-Maastrichtian boundary interval: Calcareous nannofossils from DSDP Hole 390A (Blake Nose)](/preview/png/4749276.png)
چکیده انگلیسی
The latest Cretaceous (Campanian-Maastrichtian) is characterized by several global cooling and intermittent warming events. These climatic changes influenced the palaeoceanography substantially, including changes of the deep water sources and surface water currents. One of the most prominent episodes of climatic cooling occurred during the Campanian-Maastrichtian transition. This study focuses on the palaeoclimate and palaeoceanography of the Campanian-Maastrichtian transition by analysing the calcareous nannofossils of DSDP Hole 390A (139.92-126.15Â mbsf; Blake Nose). For the examination of calcareous nannofossils sixty samples were processed using the settling technique. Biostratigraphical index taxa (Broinsonia parca constricta, Uniplanarius trifidus, and Tranolithus orionatus) suggest a late Campanian age for the major part of the studied section. The calcareous nannofossils are well preserved, highly abundant (6.80 billion specimens/gram sediment) and diverse (80 species/sample). The assemblages are dominated by Prediscosphaera spp. (20.5%), Watznaueria spp. (20.3%) and Retecapsa spp. (9.8%). Cool water taxa (Ahmuellerella octoradiata, Gartnerago segmentatum, and Kamptnerius magnificus), however, appear less frequently and do not exceed more than 1%. Due to their rarity these cool water taxa do not support the existence of an intense cooling phase during the Campanian-Maastrichtian transition at DSDP Hole 390A. Around 133Â mbsf several nannofossil taxa, however, show a distinctive turnover. Mesotrophic species like Discorhabdus ignotus, Zeugrhabdotus bicrescenticus and Zygodiscus exmouthiensis are abundant below 133Â mbsf, whereas oligotrophic taxa like Watznaueria spp., Eiffellithus spp. and Staurolithites flavus become common above this level. These changes imply a decrease in the input of nutrients, perhaps caused by a reorganization of ocean currents (Palaeo Gulf Stream) and reduced upwelling.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Micropaleontology - Volume 73, Issues 1â2, October 2009, Pages 26-36
Journal: Marine Micropaleontology - Volume 73, Issues 1â2, October 2009, Pages 26-36
نویسندگان
Christian Linnert, Jörg Mutterlose,