羅清華2006-07-252018-06-282006-07-252018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/11840隕石撞擊事件可能引發起地球內部的大規模岩漿作用、大型礦床的形成、地磁反 轉與氣候變遷，進而導致生物大規模絕滅等地球演化上的重大事件。因此，隕石撞擊 事件的研究工作對地球演化之研究具有相當程度的重要性。亞洲、澳洲、西太平洋與 印度洋地區廣佈tektite 與microtektite ，統稱為”Australasian tektites” ，雖然這個撞擊 事件跟生物絕滅與地磁逆轉等效應間的關係，還不是很清楚；而且撞擊事件形成的隕 石坑構造位置，仍有待找尋。但由於Australasian strewn field 堪稱地表分布面積最大， 也是最年輕的Strewn field ，且與石器時代人類生活有著密切關係，因此，相關之研究 工作更形重要。在探討隕石撞擊與地球演化事件關聯性時，事件發生的時序與時間是 項最為關鍵性的角色，因此，本研究計畫就Australasian strewn field 內的Australasian tektite 與Darwin Glass 進行定年學與地球化學分析工作，期望結果能提供時間的控制 點，討論撞擊與地球演化事件間之因果關係。 截至目前，本工作已完成Darwin Glass 的分析工作，並已發表一篇論文：Lo, C.-H., Howard, K.T., Chung, S.-L. and Meffre, S. (2002) Laser-fusion 40 Ar/39 Ar ages of Darwin impact glass. Meteoritics & Planetary Science 37, 1555-1562Darwin Glass represents the impart-related siliceous glass that formed in Tasmania, close to the Australasian Strewn Field. Three samples of such glass were dated using 40 Ar/39 Ar single-grain laser fusion technique, yielding isochron ages of 796-815 ka with an overall weighted mean of 816 ± 8 ka. These age data are statistically indistinguishable from those recently reported for the Australasian tektites from Southeast Asia and Australia (761-816 ka). However, considering the compositional and textural differences and the disparity from the presumed impact crater area for Australasian tektites, the Darwin glass is more likely to have resulted from an individual impact event. We therefore infer that multiple impacts, owing probably to a cometary explosion in the atmosphere, may have occurred in SE Asia and Australia during the mid-Pleistocene.application/pdf110901 bytesapplication/pdfzh-TW國立臺灣大學地質科學系暨研究所澳亞隕石撞擊事件氬同位素定年學Darwin GlassAustralasian tektitesImpact event40 Ar/39 Ar datingreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/11840/1/922116M002007.pdf