Origin of the 100-kyr Climate Cycle: Isolating Temperature and Ice Volume, 0-2Ma.

根据该奖项，PI将测试有关100 kyr气候周期起源的假设-过去约1 Ma地球气候系统的主要特征。这些知识对于理解全球地球系统的内部运作至关重要。 PI将采用详细的氧同位素和Mg/Ca古温度估计来反卷积过去200万年来d18 O上的冰量和温度分量的历史，这一过渡时期通常被称为“中更新世过渡”（MPT）。在此之前，底栖有孔虫氧同位素数据显示，占主导地位的41-kyr气候，其次是一个相对突然的100-kyr周期，持续到现在。温度和冰量的相对影响，在整个过渡，并在相对稳定的制度之前和之后的MPT，仍然是未知的。对100 kyr气候周期起源的假设的检验，无论是冰动力学、风化层侵蚀、二氧化碳逐渐变化还是热带触发的结果，都依赖于对海洋同位素的解释，主要是冰量记录。这一解释现在受到质疑，因此，对这些假设的真正检验有待于更可靠的全球冰量记录的发展。作为温度代用指标，PI将使用一种称为流动时间分辨分析（FT-TRA）的创新方法分析Mg/Ca，该方法几乎消除了污染物相的影响，并提供了d18 O分析的同一种有孔虫钙化温度估计的精度和准确度。 他们将把我们的分析集中在ODP第202航次恢复的两个新钻井现场。这些站点（1238和1242）位于热带太平洋东部的“冷舌”和“暖池”，并位于监测太平洋中央水的水深。

Under this award the PIs will test the hypotheses regarding the origin of the 100-kyr climate cycle - the dominant feature of Earth's climate system over the past ~1 Ma. This knowledge is fundamental to understanding the inner workings of the global Earth system. The PIs will employ detailed oxygen isotope and Mg/Ca paleotemperature estimates to deconvolve the history of the ice-volume and temperature components on d18O over the past two million years, a time of transition commonly referred to as the "Mid-Pleistocene Transition" (MPT). Prior to that time, benthic foraminiferal oxygen isotope data reveal a dominant 41-kyr climate, followed by a relative abrupt onset of a 100-kyr cycle that persists to the present. The relative influence of temperature and ice volume across this transition, and in the relatively stationary regimes before and after the MPT, remains unknown. Tests of hypotheses on the origin of the 100 kyr climate cycle, whether a result of ice dynamics, regolith erosion, gradual CO2 change, or tropical triggering, have relied on interpretation of the marine isotopes as primarily an ice volume record. This interpretation is now in questions and thus, true tests of these hypotheses await the development of more reliable records of global ice volume. As a temperature proxy the PIs will analyze Mg/Ca using a new and innovative method called flow through time resolved analysis, or FT-TRA which virtually eliminates effects of contaminant phases and provided precision and accuracy of estimates of calcification temperature in the same species of foraminifera analyzed for d18O. They will focus our analyses on two new drill sites, recovered by ODP Leg 202. These sites (1238 and 1242) are placed in the eastern tropical Pacific "cool tongue" and "warm pool", and are at water depths situated to monitor Pacific Central Water.