GRGC: High Resolution Stable Isotopic Fluctuations in Tropical Marine Waters

9419176 Grammer该项目的重点是使用巴哈马和伯利兹的海洋文石水泥，以提高热带海洋最近一次冰消期间稳定同位素骨骼记录的分辨率。 具体而言，我们将解决：1）与新仙女木事件之前的“融水脉冲”相关的明显变暖趋势的时间和幅度，以及迄今为止仅从冰芯记录中知道的明显更早的更高频率的冷却事件：2）近地表热带海洋沃茨在大约10- 14 ka期间的绝对温度（3）这些热带海洋胶结物在多大程度上记录了甚高频（2、5、11、22和83年）气候信号。 使用无机碳酸盐胶结物确定古海洋学和古气候变化，提供了一个机会，既可以提高海洋骨骼材料同位素记录的准确性，也可以提高热带海洋高频变化的分辨率。 这些水泥提供了一个连续的记录同位素变化的十年和可能更高的频率范围内，在数百年的时间段。 这种程度的分辨率是目前可用的海洋骨骼记录所不可能达到的，这提供了一个独特的机会，可以将热带海洋中的高频气候事件与最近记录在冰芯数据中的事件进行比较并可能相互关联。 初步工作已经确定，我们目前的样品集包含的水泥年龄范围为10.9-13.6ka（AMS 14 C），水泥的平均生长速率约为1 mm/10年， 生长了大约50-500年。 由于水泥的长期性质，许多样品在时间上重叠。 同位素的水泥表现出强烈的亏损趋势，在18 O在这段时间内，相关的值与海洋骨骼记录。 此外，由于个别胶结物中的年代至世纪尺度记录，有强有力的证据表明，胶结物记录了热带海洋中的高频同位素波动。 我们目前的数据集显示，同位素位移的时间和幅度有很强的相关性，如在新仙女木冷却事件之前报道的“融水脉冲”，以及其他更高频率的变化到更冷的条件下，迄今为止只在冰芯中报道的证据。 该提案要求提供资金，以扩大我们的初步调查结果，对这些个别水泥进行高密度AMS 14 C取样断面结合微取样（100微米尺度）同位素分析，以评估热带海洋中这些高频同位素变化。我们预计能够记录的变化，至少在十年的规模，并可能在更高的分辨率，由于连续和重叠的记录个别水泥。 这些数据应该可以提高热带海洋同位素记录的准确性和分辨率，并对我们对快速气候变化以及高纬度转移转移到热带地区的可能性的理解产生直接影响

9419176 Grammer This project focuses on the use of marine aragonite cements from the Bahamas and Belize to increase the resolution of the stable isotopic skeletal record during the latest deglaciation for tropical oceans. Specifically we will address: 1) the timing and magnitude of the apparent warming trend associated with the "melt water pulse" immediately preceding the Younger Dryas event, as well as apparent earlier higher frequency cooling events, to date only known from ice core records: 2) the absolute temperature of near surface tropical ocean waters during the period from about 10-14ka (radiocarbon age); and 3) to what degree the very high frequency (2,5,11,22 and 83yr) climate signals may be recorded in these tropical marine cements. The use of inorganic carbonate cements to determine paleo- oceanographic and paleoclimatic changes provides an opportunity to increase both the accuracy of the isotopic record derived from marine skeletal material, as well as to increase the resolution of high-frequency changes in the tropical oceans. These cements provide a continuous record of isotopic changes on a decadal and possibly higher frequency scale, over time periods of several hundreds of years. This degree of resolution has not been possible with the currently available marine skeletal records, and provides a unique opportunity to compare and possibly correlate the high- frequency climatic events in the tropical oceans with those recently documented in the ice core data. Preliminary work has established that our present sample set contains cements that range in age from 10.9-13.6ka (AMS 14C), that the cements grew at average rates of approximately 1mm/10yr, and that the cements grew for periods of approximately 50-500 years. Because of the long-lived nature of the cements, many of the samples overlap in time. Isotopically the cements exhibit a strong depletion trend in 18O over this time interval that correlates well with those values reported fo r the marine skeletal records. In addition, because of the decadal to century scale record within individual cements, there is strong evidence that the cements are recording high-frequency isotopic fluctuations in the tropical oceans. Our present data set shows a strong correlation in both the timing and magnitude of the isotopic shift as reported for the "melt-water pulse" immediately preceding the Younger Dryas cooling event as well as evidence for other higher frequency shifts to cooler conditions that to date has only been reported in ice cores. This proposal requests funds to expand upon our preliminary findings by doing high density AMS 14C sampling transects combined with microsampled (100 um scale) isotopic analysis on these individual cements to evaluate these high-frequency isotopic shifts in the tropical oceans. We anticipate being able to document changes on at least a decadal scale, and possibly at a higher resolution, due to the continuous and overlapping record of the individual cements. This data should increase both the accuracy and resolution of the isotopic records in tropical oceans, and have direct impact on our understanding of rapid climate change and the potential for high latitude shift to be carried over into the tropics