| 加拿大LITHOPROBE计划与Superior Province地质演化 |
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| 引用本文：黄始琪,董树文,陈宣华,施炜.2016.加拿大LITHOPROBE计划与Superior Province地质演化[J].地球学报,37(s1):21-36. |
| DOI：10.3975/cagsb.2016.s1.03 |
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| 基金项目:国家专项“深部探测技术与实验研究”(编号: SinoProbe-08-01) |
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| 中文摘要:加拿大岩石圈探测计划LITHOPROBE通过地质、地球物理、地球化学多种探测方法, 综合研究了加拿大地表至岩石圈地幔的地质结构和演化过程, 对北美最大太古代Superior Province克拉通的形成及增生研究堪称经典。2 720—2 680 Ma, Superior Province西部、中部和南部各原始地体及介于其间的晚太古代洋壳通过连续增生和碰撞拼贴为一体, 使得各地体原始排列方向及边界平移断层原始走向皆为近东西向。以3.0 Ga North Caribou地体为核心, 北侧Hudson Bay地体于2 720 Ma与其发生碰撞, 南部Winnipeg River地体于2 720—2 700 Ma与其碰撞并在English River盆地形成同造山期浊积岩; 往南, 相对年轻的Wabigoon 地体于2 710—2 700 Ma与Winnipeg River地体拼接, 更南侧的Wawa-Abitibi地体又拼贴于Wabigoon地体之上, 并在Quetico盆地形成同造山浊积岩和杂砂岩; 最南侧的Minnesota River Valley地体于2 680 Ma与其北侧地体拼接为一体, 先前洋壳俯冲于碰撞边界之下; 2 730—2 680 Ma, 在Superior Province东北部部发生了多期变形变质和增生活动, 形成该区北西走向造山带, 在Quebec中部地区形成巨大的马蹄形山系。Superior Province西部CWS和中部AG岩石圈地震剖面显示, 主要的地壳和地幔岩石圈俯冲带都向北缓倾; 以Timiskaming型砾岩沉积, 碱性岩浆岩发育, 壳源花岗岩侵位, 区域变质作用, 热液循环, 金矿脉定位以及造山后冷却诸多地质活动为特征, 2 680—2 600 Ma Superior Province发生克拉通化, 表明该时期Superior Province存在一个稳定的热扩散地幔隆起带。2 000 km规模原始地块和洋壳的增生及与之相伴的地块推覆和叠置, 揭示Superior Province各地体新太古代的拼合是一个似板块活动过程。 |
| 中文关键词:LITHOPROBE, Superior Province 太古代 克拉通 增生 |
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| LITHOPROBE Program and Geological Evolution of Superior Province in Canada |
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| Abstract:Combining geological, geophysical and geochemical explore methods, LITHOPROBE program of Canada successfully researched the structural features and evolutionof the lithosphere of Canada. The study about the formation and evolution of Superior Province craton which is the largest Archean craton of North America is very typical. Disparate fragment of Mesocarchean to Eoarchean protocontinental crust and intervening tracts of Neoarchean oceanic crust were assembled through successive accretionary and collisional events between 2 720 and 2 680 Ma, resulting in the first-order easterly alignment of terranes. The 3.0 Ga North Cariobou terrane acted as a nucleus during collision with the Hudson Bay terrane to the north at 2 720 Ma, and the Winnipeg River terrane on the south(2 720–2 700 Ma), where synorogenic turbidites were trapped in the English River basin. Docking of the juvenile Wabigoon terrane further to the south occurred at 2 710–2 700 Ma, followed by collision of the Wawa-Abitibi terrane and syntectonic deposition of Quetico basin turbidites and Porcupine group wackes. The final event welded the Minnesota River Valley terrane to the southern Superior margin and tectonically underplated a wedge of probable oceanic crust beneath it. Polyphase deformation and metamorphism occurred at 2 730 to 2 680 Ma in the northeastern Superior Province andeast-trending belts and structures bend into northerly trends through a broad oroclinal flexure in central Quebec. In the regional LITHOPROBE transects CWS and AG, prominent crust reflectivity and mantle lithospheric features dip gently northward to central North Caribou latitudes.Several late-tectonic events recognized across the Superior Province characterized the cratonization process between 2 680 and 2 600 Ma. Deposition of “Timiskaming-type” conglomerates, alkaline magmatism, emplacement of crust-derived granites, regional metamorphism, hydrothermal fluid circulation, lode gold localization, and post-orogenic cooling express thermal relaxation and stabilization of a refractory lithosphere mantle keel. The progressive accretion of protocontinental and oceanic domains on a 2 000 km length scale, coupled with three-dimensional evidence for terrane stacking, provide compelling evidence that plate-tectonic-like processes drove Neoarchean assembly of the Superior Province. |
| keywords:LITHOPROBE Superior Province Archean craton accretion |
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