EAGER: Sedimentologyand Tephrochronology of Caves in the Melinau Karst, Sarawak, Malaysia

马来西亚沙捞越Melinau喀斯特洞穴的沉积学和年代学唐纳德·A·麦克法兰，克莱蒙特·麦肯纳学院EAR-0952398ABSTRACT马来西亚沙捞越古农木鲁国家公园成立于1974年，旨在保护其世界级的地下环境，并于2000年被确认为世界遗产。目前，这一遗产包括约295公里绘制的洞穴，包括世界上一些最大的通道和洞穴。这项建议的重点是解决在几个木鲁洞穴的沉积物中保存的突出的火山灰层的年龄和来源，使用这个独特的计时器来了解洞穴的沉积历史，并分离出木鲁洞穴中同时存在的地球化学特征。PIS认为，间接证据表明火山灰层是由更年轻的托巴喷发形成的--这是一次起源于苏门答腊岛北部的灾难性事件，被认为是过去100万年地球历史上最猛烈的火山事件。如果木鲁火山灰真的来自托巴，它将为研究火山灰落下的模式提供有价值的新见解，从而可能对东南亚的生态系统和人类人口产生影响。如果火山灰被证明来自其他地方，那么它一定代表了一次迄今未被认识到的意义重大的喷发。在任何一种情况下，在木鲁石笋中确定相应的地球化学特征，都可能为从东南亚洞穴中开发古喷发记录奠定基础。

Sedimentology and Tephrochronology of caves in the Melinau Karst, Sarawak, Malaysia.Donald A. McFarlane, Claremont McKenna CollegeEAR - 0952398ABSTRACT Gunung Mulu National Park, Sarawak, Malaysia, was established in 1974 to protect its world-class subterranean environment, and recognized for World Heritage status in 2000. Currently, this heritage incorporates some 295 kms of mapped cave, including some of the largest passages and chambers in the World. This proposal focuses on resolving the age and origin of a prominent volcanic ash layer preserved in the sediment deposits of several Mulu caves, on using that distinctive chrono-marker to understand the depositional history of the caves, and on isolating a concurrent geochemical signature in Mulu speleothems.PIs believe that the circumstantial evidence points to the ash layer being formed by the Younger Toba eruption - a cataclysmic event originating in northern Sumatra that is recognized as the most violent volcanic event in the past million years of Earth history. If the Mulu ash does prove to come from Toba, it will provide valuable new insights into the pattern of ash-fall and hence it's probable impact on ecosystems and human populations in southeast Asia. If the ash proves to originate elsewhere, then it must represent a hitherto unrecognized eruption of great significance. In either case, identifying a corresponding geochemical signature in a dated Mulu stalagmite may lay the groundwork for developing paleo-eruption records from speleothems Southeast Asia.