澳亚散布区(英语:Australasian strewnfield)是最大且最年轻的似曜岩散布区,研究表明形成似曜岩的陨石撞击可能发生在约79万年前的东南亚,科学家最近估计其可能覆盖约10%–30%的地球表面[1]

澳亚散落区的位置,深色阴影代表似曜岩的发现地

特征

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澳亚散布区有约79万年的历史[2][3],范围覆盖大部分东南亚泰国老挝越南柬埔寨中国华南地区),陨石撞击产生的物质亦横跨太平洋印度洋,分布菲律宾印度尼西亚马来西亚爪哇澳大利亚塔斯马尼亚等地区。自1960年代以来,科学家们普遍认为散布区从中国南部的海南向南延伸至澳大利亚,或大约10%的地球表面,随后在非洲和塔斯马尼亚的发现则将这比例进一步扩大到20%[1]。最近在西藏北部和广西的新发现将散布地增加至约地球表面的30%左右,即近1.5亿平方公里[1]

陨石坑

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地球撞击资料库列出了大约26个已知年龄小于100万年的陨石坑,除了位于摩洛哥的3公里阿古达尔陨石坑(Agoudal Crater)之外,几乎所有陨石坑的直径都小于2公里。最接近100万年这一时间段的是哈萨克斯坦14公里长的扎马辛陨石坑英语Zhamanshin crater,其曾一度被认为是澳亚散布区的源头[4]

然而由于澳亚散布区的巨大规模,科学家们推测其原生陨石坑比现时已知的陨石坑要大得多[1][5][6]。格哈特·施密特(Gerhard Schmidt)和约翰·T·瓦森(John T. Wasson)在1993年认为该陨石坑位于湄公河谷下方14–17公里[7],杰克·哈通(Jack Hartung)和克里斯蒂安·科贝尔英语Christian Koeberl在隔年提出原生陨石坑位于柬埔寨的洞里萨湖[6],同年比利·P·格拉斯(Billy P. Glass)认为陨石坑位在柬埔寨,其直径在32–114公里之间[5],而查尔斯·施内茨勒英语Cherles Schnetzler和约翰·F·麦克霍恩(John F. Mchone)则表示原生陨石坑在老挝南部,直径约35–40公里[8]。格拉斯随后在1999年也将老挝南部或邻近地区视为可能的源头[9][10],李孟阳和魏国彦认为陨石坑可达90–116公里[9],而格拉斯等人则用铍-10假设陨石坑位于老挝南部到海南之间,有可能在东京湾[11][12]。最近的2019年,凯利·西埃(Kelly Sieh)等人基于4项证据表明该原生陨石坑位于老挝南部的布拉万火山场之下[13]。另一方面,在泰国中部发现层状似曜岩的瓦森推测所谓的澳亚散布区可能只是一连串分布在中南半岛的小型多重撞击事件[14][15],但此推论却被科学界认为只会衍生出更多的问题[6]

南极洲威尔克斯地陨石坑被认为是可能的主撞击坑[16],此撞击也有可能引发了78.1万年前的布容尼斯-松山反转[17][18]

直立人

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在中国南部广西壮族自治区百色市发掘出的与似曜岩一起发现的考古文物表明,该地区在撞击期间和撞击后居住著直立人[19][20][21][22],在碎片场内亦发现了石器以及可能由撞击火灾引起的木炭层[19]

参见

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参考资料

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  1. ^ 1.0 1.1 1.2 1.3 Povenmire H., Liu W. and Xianlin I. (1999) "Australasian tektites found in Guangxi Province, China,"页面存档备份,存于互联网档案馆) 30th Annual Lunar and Planetary Science Conference, Houston, March 1999.
  2. ^ Schneider D.A., Kent D.V. & Mello G.A. 1992. A detailed chronology of the Australasian impact event, the Brunhes-Matuyama geomagnetic polarity reversal, and global climatic change. Earth and Planetary Science Letters 111, 395-405.
  3. ^ Pillans, B., Simmonds, P., et al (2012) "Tektites, minitektites and microtektites from the Kalgoorlie region, Western Australia"页面存档备份,存于互联网档案馆), Australian Regolith and Clays Conference, Mildura, 7–10 February 2012.
  4. ^ B.P. Glass (1979), Zhamanshin crater, a possible source of Australasian tektites? Geology, July 1979, v. 7, p. 351-353
  5. ^ 5.0 5.1 Glass B.P. and Pizzuto J.E. (1994) "Geographic variation in Australasian microtektite concentrations: Implications concerning the location and size of the source crater,"页面存档备份,存于互联网档案馆) J of Geophysical Research, vol 99, no E9, 19075-19081, Sept 1994.
  6. ^ 6.0 6.1 6.2 Hartung J. and Koberl C. (1994) "In search of the Australasian tektite source crater: the Tonle sap hypothesis"页面存档备份,存于互联网档案馆), Meteoritics.
  7. ^ Schmidt G. and Wasson J. (July 1993) "Masses of the impactor, the Australasian tektites, and size estimates of the main source crater"页面存档备份,存于互联网档案馆), Meteoritics, vol 28 no .3, 430
  8. ^ Schnetzler C. C. and Mchone J.F. (1996) "Source of Australasian tektites: Investigating possible impact sites in Laos"页面存档备份,存于互联网档案馆), Meteoritics and Planetary Science, Vol. 31, p. 73-76
  9. ^ 9.0 9.1 Lee M.Y. and Wei K.Y. (2000) "Australasian microtektites in the South China Sea and West Philippine Sae: implications for age, size and location of the impact crater", Meteoritics and Planetary Science, vol 35, no. 6, 1151-1155.
  10. ^ Glass B.P. (1999) "Muong Nong-type Australasian tektites: implications regarding the parent material and source area,"页面存档备份,存于互联网档案馆) Ninth Annual V.B.m Goldschmidt Conference, Massachusetts, August 1999.
  11. ^ P. Ma et al (2001)10Be in Muong Nong-Type Australasian Tektites: Constraints on the Location of the Source Crater页面存档备份,存于互联网档案馆), Lunar and Planetary Science XXXII (2001)
  12. ^ Whymark, A. (2013) Review Of The Australasian Tektite Source Crater Location And Candidate Structure In The Song Hong-Yinggehai Basin, Gulf Of Tonkin页面存档备份,存于互联网档案馆), 44th Lunar and Planetary Science Conference (2013)
  13. ^ Sieh, Kerry; Herrin, Jason; Jicha, Brian; Schonwalder Angel, Dayana; Moore, James D. P.; Banerjee, Paramesh; Wiwegwin, Weerachat; Sihavong, Vanpheng; Singer, Brad; Chualaowanich, Tawachai; Charusiri, Punya. Australasian impact crater buried under the Bolaven volcanic field, Southern Laos. Proceedings of the National Academy of Sciences. December 30, 2019, 117 (3): 1346–1353. Bibcode:2020PNAS..117.1346S. PMC 6983392 . PMID 31889003. doi:10.1073/pnas.1904368116 . 
  14. ^ Wasson et al (1995) Field recovery of layered tektites in northeast Thailand. Evidence of a large-scale melt sheet. J. Geophysics. Res. 100, 14383-14390.
  15. ^ Wasson, J.T. (1991) Layered tektites: A multiple impact origin for the Australasian tektites. Earth Planet. Sci. Lett. 102, 95-105
  16. ^ Schmidt, RA. Australites and Antarctica. Science. 1962, 138 (3538): 443–444. Bibcode:1962Sci...138..443S. PMID 17794921. S2CID 5626171. doi:10.1126/science.138.3538.443. Abstract. 
  17. ^ Glass B.P. & Heezen B.C. 1967. Tektites and geomagnetic reversals. Scientific American 217, 32-38.
  18. ^ Glass, B. P., Swincki, M. B., & Zwart, P. A. (1979). "Australasian, Ivory Coast and North American tektite strewnfields - Size, mass and correlation with geomagnetic reversals and other earth events"页面存档备份,存于互联网档案馆) Lunar and Planetary Science Conference, 10th, Houston, Tex., March 19–23, 1979, p. 2535-2545.
  19. ^ 19.0 19.1 Handaxe and tektites in Bose, China. [2012-04-23]. (原始内容存档于2011-08-30). 
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  21. ^ SCI/TECH | Asia's oldest axe tools discovered. BBC News. 2000-03-03 [2015-10-20]. (原始内容存档于2023-05-31). 
  22. ^ Antón, Susan C.; Swisher, Iii, Carl C. Early Dispersals of Homo from Africa. Annual Review of Anthropology (Annual Reviews). October 2004, 33: 271–296. doi:10.1146/annurev.anthro.33.070203.144024.