东非造山运动

东非造山运动 (EAO)是东西两块冈瓦纳大陆(澳洲–印度–南极洲与非洲–南美)沿莫桑比克带于新元古代拼合的主要阶段。^{[2]:320–321, 324}

东非和库嘎造山带^{[1]:Fig. 10, p. 19}

冈瓦纳大陆的拼合

1980年代早期，麦克威廉姆斯首先提出了冈瓦纳大陆在晚前寒武纪期间由两个更古老的碎块沿泛非洲莫桑比克带拼合而来。^[3]十年后，这次合并被命名为东非造山运动，不过人们也同时认识到它的过程远比原来所想要复杂。先是几个零碎的曾组成罗迪尼亚超大陆的克拉通互相拼合，接着才是两大块陆地互相拼合，形成相对短命的冈瓦纳超大陆。^[2]

关于这次合并，有两个假说。^[4]其一，EAO从岛弧合并为主的增生运动在新元古代发展为碰撞造山运动，同时阿扎尼亚与刚果-坦桑尼亚-班韦乌卢板块于约640Ma相撞。^[5]其二，约750-530Ma的东冈瓦纳拼合过程分多个阶段，可将东非造山运动分为两个主要时期：早些的EAO(约750-620Ma)和更晚的库嘎造山运动(约570-530Ma)。^[6]在前者发生时，后者体现为两个同时发生的事件：分别是印度和澳-东南极、印度-阿扎尼亚的碰撞。另外，后一种情况的两个造山带在马达加斯加相交，是阿扎尼亚-印度碰撞的理论位置，库嘎造山运动的这一部分应被重新命名为马达加斯加造山运动。^{[7]:256–257}

侵蚀与寒武纪大爆发

东非造山运动最终形成了跨冈瓦纳山脉，有超过8000km长、1000km宽。这山系的沉积区也被称为冈瓦纳扇，在美国以约10km厚的沉积物覆盖了100000km²。沉积过程持续了超过2.6亿年，约550Ma的寒武纪大爆发就在这时发生。这些空前的沉积可能为早期动物的多样化提供了物质基础。^[8]

造山带受到的侵蚀猛烈到到奥陶纪就变成了埃塞俄比亚的夷平面。^{[9]:33–64[10]:287–296}

新生代

新生代东非裂谷主要从东非的元古代裂谷前系统所遗留的复杂模式演化而来。^[11]:325它穿过坦桑尼亚克拉通东部的莫桑比克带。^{[12]:106–108}

参考

1. Meert 2003
2. Stern 1994
3. McWilliams 1981，Abstract
4. For a discussion see Meert 2003，Discussion, p. 31; Collins & Pisarevsky 2005，Comparisons with other models, pp. 256–257; Meert & Lieberman 2008，Assembling Gondwana: polyphase or simple?, pp. 9–11; Nance, Murphy & Santosh 2014，Pannotia (Gondwana), pp. 12, 14
5. Azania was defined by Collins & Windley 2002，Discussion, pp. 334–335 and named by Collins & Pisarevsky 2005，第244頁
6. Meert 2003，Abstract
7. Collins & Pisarevsky 2005，Comparisons with other models
8. Squire et al. 2006，Abstract
9. Abbate, Ernesto; Bruni, Piero; Sagri, Mario. Geology of Ethiopia: A Review and Geomorphological Perspectives. Billi, Paolo (编). Landscapes and Landforms of Ethiopia. World Geomorphological Landscapes. 2015. ISBN 978-94-017-8026-1. doi:10.1007/978-94-017-8026-1_2. 
10. Coltorti, M.; Dramis, F.; Ollier, C.D. Planation surfaces in Northern Ethiopia. Geomorphology. 2007, 89 (3–4). doi:10.1016/j.geomorph.2006.12.007. 
11. Ring 1994，Conclusions
12. Aulbach, Rudnick & McDonough 2011，Geology and samples

资料

• Aulbach, S.; Rudnick, R. L.; McDonough, W. F. Evolution of the lithospheric mantle beneath the East African Rift in Tanzania and its potential signatures in rift magmas 478. 2011: 105–125 [6 January 2018]. ISBN 978-0-8137-2478-2. doi:10.1130/2011.2478(06).  |journal=被忽略 (帮助)
• Collins, A. S.; Pisarevsky, S. A. Amalgamating eastern Gondwana: The evolution of the Circum-Indian Orogens. Earth-Science Reviews. 2005, 71 (3–4): 229–270. Bibcode:2005ESRv...71..229C. CiteSeerX 10.1.1.558.5911  . doi:10.1016/j.earscirev.2005.02.004. 
• Collins, A. S.; Windley, B. F. The tectonic evolution of central and northern Madagascar and its place in the final assembly of Gondwana (PDF). The Journal of Geology. 2002, 110 (3): 325–339 [6 January 2018]. Bibcode:2002JG....110..325C. doi:10.1086/339535. hdl:2440/34282  . 
• McWilliams, M. O. Palaeomagnetism and Precambrian tectonic evolution of Gondwana 4. 1981: 649–687. ISBN 9780444419101. doi:10.1016/S0166-2635(08)70031-8.  |journal=被忽略 (帮助)
• Meert, J. G. A synopsis of events related to the assembly of eastern Gondwana (PDF). Tectonophysics. 2003, 362 (1): 1–40 [6 January 2018]. Bibcode:2003Tectp.362....1M. doi:10.1016/S0040-1951(02)00629-7. 
• Meert, J. G.; Lieberman, B. S. The Neoproterozoic assembly of Gondwana and its relationship to the Ediacaran–Cambrian radiation. Gondwana Research. 2008, 14 (1): 5–21. Bibcode:2008GondR..14....5M. S2CID 2814283. doi:10.1016/j.gr.2007.06.007. 
• Nance, R. D.; Murphy, J. B.; Santosh, M. The supercontinent cycle: a retrospective essay. Gondwana Research. 2014, 25 (1): 4–29. Bibcode:2014GondR..25....4N. doi:10.1016/j.gr.2012.12.026. 
• Ring, U. The influence of preexisting structure on the evolution of the Cenozoic Malawi rift (East African rift system). Tectonics. 1994, 13 (2): 313–326 [6 January 2018]. Bibcode:1994Tecto..13..313R. doi:10.1029/93TC03188. 
• Squire, R. J.; Campbell, I. H.; Allen, C. M.; Wilson, C. J. Did the Transgondwanan Supermountain trigger the explosive radiation of animals on Earth? (PDF). Earth and Planetary Science Letters. 2006, 250 (1): 116–133 [11 September 2017]. Bibcode:2006E&PSL.250..116S. doi:10.1016/j.epsl.2006.07.032. 
• Stern, R. J. Arc assembly and continental collision in the Neoproterozoic East African Orogen: implications for the consolidation of Gondwanaland (PDF). Annual Review of Earth and Planetary Sciences. 1994, 22 (1): 319–351 [6 January 2018]. Bibcode:1994AREPS..22..319S. doi:10.1146/annurev.ea.22.050194.001535.