A warm interglacial episode during oxygen isotope stage 11 in northern Chile
A warm interglacial episode during oxygen isotope stage 11 in northern Chile
复制标题
智利北部氧同位素第 11 阶段的一次温暖间冰期事件
DOI：
10.1016/s0277-3791(96)00062-5
复制
发表时间：
1996
影响因子：
4
通讯作者：
N. Guzmán
中科院分区：
文献类型：
--
作者：
Luc Ortlieb;A. Diaz;N. Guzmán
智利北方梅希约内斯半岛（23°S）中更新世海岸沉积物的古生物学、地貌地层学和年代学数据表明，在氧同位素第11阶段高海台事件期间，气候条件特别温暖。一个异常的暖水软体动物组合来自于被指定为该间冰期的地点，其中包括几种生活在6°S（或14°S）以北的外来物种，这些物种在随后的中更新世和晚更新世（或全新世）间冰期时期并不存在于该地区。在强烈的厄尔尼诺事件发生后，在南纬23°的受保护地区，现在可能只发现两种这种生活在生活区外的物种。热异常软体动物组合（TAMA）中的许多物种与秘鲁中北部（9°S）桑塔附近的一个封闭的浅泻湖中的物种在一个短暂的中全新世时期是相同的。因此，新的发现表明，泻湖和受保护的海湾比开放的海洋环境要温暖得多。40万事实上，冷水动物在暴露的海岸线部门的共同出现，当时表明，沿海涌升活动和洪堡电流的影响并没有强烈减少。在中Brunhes事件期间，泻湖和受保护海湾中普遍存在的温水条件可能反映了比现在普遍存在的特别温暖的空气温度和不同的海洋-大气关系。这些数据支持氧同位素第11阶段是最温暖的间冰期的假设，至少在南半球是如此。
Combined paleontological, morphostratigraphic and geochronologic data from emerged Middle Pleistocene coastal deposits in Mejillones Peninsula (23°S), northern Chile, strongly suggest that climatic conditions were particularly warm during the particularly warm during the Oxygen Isotope Stage 11 high seastand episode. An anomalous warm-water molluscan assemblage from localities assigned to that interglaciation included several extralimital species, presently living only north of 6°S (or 14°S), that were not present in the area during subsequent Middle and Late Pleistocene, or Holocene, interglacial episodes. Only two of these extralimital species may be found nowadays at the 23°S latitude, in a protected locality, immediately after the occurrence of strong El Niño events. Many of the species of the thermally anomalous molluscan assemblage (TAMA) are the same as those which lived in a closed shallow lagoon near Santa, north-central Peru (9°S) during a brief mid-Holocene episode. The new findings thus indicate that lagoonal and protected embayments were significantly warmer than the open marine environment ca. 400 ka. Actually, the co-occurrence of cool water fauna in exposed sectors of the coastline at that time suggests that the coastal upwelling activity and the Humboldt Current effects were not strongly reduced. The warm-water conditions prevailing in lagoons and protected bays during the Mid-Brunhes episode may reflect particularly warm air temperatures and distinct ocean-atmosphere relationships than those prevalent nowadays. These data support the hypothesis that the Oxygen Isotope Stage 11 was the warmest interglaciation, at least in the southern hemisphere.