New maastrichtian oxygen and carbon isotope record: Additional evidence for warm low latitudes
New maastrichtian oxygen and carbon isotope record: Additional evidence for warm low latitudes
复制标题
新的马斯特里赫特氧和碳同位素记录：温暖低纬度地区的额外证据
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
T. B. Afanasyeva
中科院分区：
文献类型：
--
作者：
Y. Zakharov;A. Popov;Y. Shigeta;O. P. Smyshlyaeva;E. Sokolova;R. Nagendra;T. Velivetskaya;T. B. Afanasyeva
白垩纪通常以温室条件为特征。然而，我们对科里亚克高原和库页岛(俄罗斯远东)生物成因碳酸盐的同位素组成的数据表明，在马斯特里赫特山脉期间，高纬度和中纬度地区的温度急剧下降，只有马斯特里赫斯山脉早期和晚期略有升温。同时，马斯特里赫特时期低纬地区的气候条件也有相互矛盾的证据。关于西部内海(北美)和其他一些地区马斯特里赫特软体动物的新的和以前公布的同位素数据表明，根据所研究的大多数马斯特里赫斯浮游有孔虫的氧同位素组成计算的热带深海表面温度显然被低估了。热带浮游有孔虫的同位素温度异常低。这可能既反映了首先由热带上升流影响引起的当地条件，也反映了马斯特里赫特浮游有孔虫在弱分层(混合)海洋条件下在热带大范围垂直间隔内迁徙的能力。马斯特里赫斯的平均热带深海表层古温度估计可能在26.6-30.2℃左右，但显然没有达到阿尔比安晚期和都灵晚期的水平(32±3℃)。早期马斯特里赫期末期和白垩纪-第三纪界线时间的负碳同位素漂移似乎与气温下降和大气和水圈中氧含量的最终减少有关。
The Cretaceous period was generally characterized by greenhouse conditions. Nevertheless, our data on isotopic composition of biogenic carbonates from the Koryak Upland and Sakhalin (Russian Far East) show that during the Maastrichtian, temperatures dropped sharply at high and middle latitudes, with only a slight warming in the early Late Maastrichtian. At the same time, there is contradictory evidence on climatic conditions for low latitude areas during Maastrichtian time. The new and previously published isotopic data on Maastrichtian mollusks in the Western Interior Seaway (North America) (WIS) and some other areas suggest that tropical deep-sea surface temperatures calculated from the oxygen isotopic composition of the majority of investigated Maastrichtian planktic foraminifera are, obviously, underestimated. Unusually low isotopic temperatues were obtained for tropical planktic foraminifera. This probably reflects both local conditions provoked, first of all, by the influence of tropical upwelling zones, and the ability of Maastrichtian planktic foraminifera to migrate within a large vertical interval in the tropical zone in conditions of weakly stratified (well-mixed) ocean. The average tropical deep-sea surface paleotemperature estimates for the Maastrichtian could have been about 26.6–30.2°C, but, apparently, did not reach the level denoted for the Late Albian and Turonian (32±3°C). Negative carbon-isotopic shifts at the end of the early Maastrichtian and the Cretaceous-Tertiary boundary time seem to be connected with the fall of temperature and eventual reduction of oxygen content in the atmosphere and hydrosphere.