کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4718324 1639102 2014 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Paleoclimatic and paleoenvironmental records of the Oligocene–Miocene transition, central Jylland, Denmark
ترجمه فارسی عنوان
پرونده های پالئوسلیمتیک و پالووآنتیولوژیکی انتقال جفتی اولیگوسنای، مرکزی جیلند، دانمارک
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی


• The Oligocene–Miocene (O/M) transition onshore Denmark has been studied.
• Combined dinocyst, δ13C and magnetostratigraphy position the O/M boundary.
• New geochemical data show a decrease in MAT of ~ 2 °C near the O/M boundary.
• The temperature minimum coincides with a distinct sequence boundary (SB B).
• This supports a correlation between the global Mi-1 cooling event and SB B.

A multidisciplinary study of the Oligocene/Miocene (O/M) transition was carried in two boreholes (Harre-1 and Horn-1) from the Danish land area in order to improve the understanding of the paleoclimatological and environmental changes across the Mi-1, the earliest Miocene cooling event. Dinoflagellate cyst (dinocyst) biostratigraphy, supported by re-evaluation of the foraminiferid biostratigraphy, a new set of magnetic data and stable carbon isotope (δ13C) records were applied to improve the age model for the studied succession; as well as the positioning of the O/M boundary. These data further enabled a correlation of the two investigated profiles with the well-established stratigraphical framework for the Danish area.The BIT index (an organic proxy indicating the relative input of soil-derived organic matter), dinocyst assemblages and palynofacies have been applied for establishing the paleoenvironmental changes across the Oligocene/Miocene (O/M) boundary. Our data indicate a shallowing upward trend in the latest Oligocene, resulting in the establishment of a very restricted marine setting in the earliest Miocene. Our study confirms that the O/M boundary is located at a sequence boundary (the local sequence boundary B — SB B) and corresponds to an increase in terrestrial organic matter input.A mean air temperature record based on the MBT′/CBT proxy reveals an ~ 2 °C drop in temperature at the O/M and the sequence boundary. Our findings confirm previous suggestions that this sequence boundary is a result of the glacio-eustatic sea level fall related with the Mi-1 cooling event. The unconformity at the sequence boundary probably correlates with the coldest part of Mi-1, and thus no deposits from this period have been preserved. This suggests that the temperature drop might have been greater than 2 °C.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Geology - Volume 350, 1 April 2014, Pages 1–15
نویسندگان
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