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首页> 外文期刊>Paleoceanography >Insolation forcing of coccolithophore productivity in the western tropical Indian Ocean over the last two glacial-interglacial cycles
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Insolation forcing of coccolithophore productivity in the western tropical Indian Ocean over the last two glacial-interglacial cycles

机译：在过去的两个冰川 - 中间峡湾循环中，在西部热带印度洋中的缺失迫使抗Coccolthophore生产力

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摘要

We present a new coccolithophore productivity reconstruction spanning the last 300ka 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 300ka to the present, with reconstructed EPP values ranging from 91 to 246gC/m(2)/yr. Coccolithophore assemblages and coccolith fraction Sr/Ca indicate three main phases of productivity change, with major changes at 160 and 46ka. 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 to 160ka, interpreted to be due to stronger Walker Circulation while the declining productivity from 160ka to the present day is a consequence of its weakening intensity.
机译：我们展示了一种新的Coccoltholeophore生产力重建，跨越从西部热带印度洋（IO）检索到的核心Geob12613-1中的最后300ka，这是一个主要来自IO东部的温暖和寡营养表面水域。校准的基于组件的生产率指数的应用表明，估计的初级生产率（EPP）从300KA到现在的降低，重构的EPP值范围为91至246g / m（2）/ Yr。 Coccolthophore组件和Coccolith馏分Sr / Ca表示生产率变化的三个主要阶段，160和46ka的主要变化。生产率和水柱分层记录显示出显性的预测和倾斜周期，似乎在最后两个冰川 - 中间峡峡循环上控制研究区域的古形原营率。由于对贸易风的加强响应不呈现出态度最大值而导致的热量潜水导致EPP中的峰值。与东部IO生产力和分层COCCLETHOCHOLORE数据的比较揭示了与我们的记录良好的对应，表明我们的研究区具有强烈的热带太平洋影响。这两个记录显示出300至160ka的高生产率，被解释为由于沃克循环强，而160ka到现在的生产力下降是其弱化强度的结果。

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