Insolation forcing of coccolithophore productivity in the western tropical Indian Ocean over the last two glacial-interglacial cycles
Insolation forcing of coccolithophore productivity in the western tropical Indian Ocean over the last two glacial-interglacial cycles
复制标题
DOI：
10.1002/2017pa003102
复制
发表时间：
2017-07
期刊：
影响因子：
--
通讯作者：
D. Tangunan;K. Baumann;J. Pätzold;R. Henrich;M. Kučera;R. Pol-Holz;J. Groeneveld
中科院分区：
文献类型：
--
作者：
D. Tangunan;K. Baumann;J. Pätzold;R. Henrich;M. Kučera;R. Pol-Holz;J. Groeneveld
我们在取自热带印度洋西部（IO）的核心 GeoB12613-1 中提出了跨越过去 300ka 的新的颗石藻生产力重建，该区域的温暖和贫营养表层水主要来自东部 IO。应用基于组合的校准生产力指数表明，估计初级生产力（EPP）从 300 ka 下降到现在，重建的 EPP 值范围为 91 至 246 g C/m2/yr。颗石藻组合和颗石石组分 Sr/Ca 表明生产力变化的三个主要阶段，主要变化在 160 ka 和 46 ka。生产力和水柱分层记录显示出主导的进动和倾角周期性，这似乎控制了研究区最近两个冰期-间冰期旋回的古生产力。由于响应最大日照的信风增强导致温跃层变浅，导致 EPP 达到峰值。与东部 IO 生产力和层化颗石藻数据的比较表明，与我们的记录具有良好的一致性，表明我们的研究区域受到强烈的热带太平洋影响。这两个记录都显示从 300 ka 到 160 ka 的生产力很高，解释为由于沃克环流更强，而从 160 ka 到现在的生产力下降是其强度减弱的结果。
We present a new coccolithophore productivity reconstruction spanning the last 300 ka in core GeoB12613-1 retrieved from the western tropical Indian Ocean (IO), an area that mainly derives its warm and oligotrophic surface waters from the eastern IO. Application of a calibrated assemblage-based productivity index indicates a reduction in estimated primary productivity (EPP) from 300 ka to the present, with reconstructed EPP values ranging from 91 to 246 g C/m2/yr. Coccolithophore assemblages and coccolith fraction Sr/Ca indicate three main phases of productivity change, with major changes at 160 and 46 ka. The productivity and water-column stratification records show both dominant precession and obliquity periodicities, which appear to control the paleoproductivity in the study area over the last two glacial-interglacial cycles. Shallowing of the thermocline due to strengthening of the trade winds in response to insolation maxima resulted to peaks in EPP. Comparison with the eastern IO productivity and stratification coccolithophore data reveals good correspondence with our records, indicating a strong tropical Pacific influence in our study area. Both of these records show high productivity from 300 ka to 160 ka, interpreted to be due to stronger Walker Circulation while the declining productivity from 160 ka to the present day is a consequence of its weakening intensity.