气候变化领域集成服务门户(CCPortal): Age model, stable isotopes, major element proportions and endmember unmixing results from four western tropical Atlantic cores

CCPortal

DOI	https://doi.org/10.1594/PANGAEA.831553
	Age model, stable isotopes, major element proportions and endmember unmixing results from four western tropical Atlantic cores
	Govin; Aline; Chiessi; Cristiano Mazur; Zabel; Matthias; Sawakuchi; André Oliveira; Heslop; David; Hörner; Tanja; Zhang; Yancheng; Mulitza; Stefan
发布日期	2014-04-22
数据集类型	dataset
英文简介	We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12° N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9° N, while the core at 12° N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9° N) and of Amazon material ("%-Amazon", at 12° N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during interglacials in comparison to glacial periods. High %-Andes values observed during periods of high austral summer insolation reflect the increased delivery of suspended sediments by Andean tributaries and enhanced Amazonian precipitation, in agreement with western Amazonian speleothem records. Increased Amazonian rainfall reflects the intensification of the South American monsoon in response to enhanced land-ocean thermal gradient and moisture convergence. However, low %-Amazon values obtained at 12° N during the same periods seem to contradict the increased delivery of Amazon sediments. We propose that reorganizations in surface ocean currents modulate the northwestward transport of Amazon material. In agreement with published records, the seasonal North Brazil Current retroflection is intensified (or prolonged in duration) during cold substages of the last 250 ka (which correspond to intervals of high DJF or low JJA insolation) and deflects eastward the Amazon sediment and freshwater plume.
空间范围	Median Latitude: 11.946956 * Median Longitude: -48.198216 * South-bound Latitude: 5.433333 * West-bound Longitude: -58.330000 * North-bound Latitude: 37.799833 * East-bound Longitude: -10.166500
时间范围	1995-07-09T00:00:00 - 2001-04-21T20:21:00
语种	英语
国家	国际
学科大类	气候变化
学科子类	气候变化
文献类型	数据集
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/233548
推荐引用方式 GB/T 7714	Govin,Aline,Chiessi,et al. Age model, stable isotopes, major element proportions and endmember unmixing results from four western tropical Atlantic cores.2014-04-22.https://doi.org/10.1594/PANGAEA.831553.