On causal links between flood basalts and continental breakup
On causal links between flood basalts and continental breakup
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DOI：
10.1016/s0012-821x(98)00282-9
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发表时间：
1999-03-15
影响因子：
5.3
通讯作者：
Besse, J
中科院分区：
文献类型：
--
作者：
Courtillot, V;Jaupart, C;Besse, J
近三十年来，人们一直注意到大陆溢流玄武岩和解体之间的时间巧合。在过去的300 Ma中产生了八种主要的大陆溢流玄武岩。最近的一次是埃塞俄比亚圈闭，大约在30 Ma时爆发了100万年。红海和亚丁湾的裂谷，可能还有东非裂谷，大约在同一时间开始。第二个类似陷阱的事件发生在2 Ma左右，真正的洋壳将在接下来的几个万年内形成。我们发现类似的关系为60马格陵兰陷阱和北大西洋，65马德干陷阱和西北印度洋，132马巴拉那陷阱和南大西洋，184马卡鲁陷阱和西南印度洋，和200马大西洋中部边缘洪水玄武岩和开放的大西洋中部。250马西伯利亚和258马峨眉山陷阱似乎与主要的，如果流产，裂谷阶段。裂陷不对称、明显的三联点和裂陷扩展（朝向溢流玄武岩区）是共同的特征，这些特征可能与溢流玄武岩、向海倾斜反射层和洋壳产生的相对时间有关，取决于若干与羽流和岩石圈有关的因素。我们提出了一个混合的情况下，“主动/被动”裂谷占这些意见。在所有情况下，一个活跃的组成部分（地幔柱和由此产生的溢流玄武岩）是一个主要洋盆分裂的先决条件。但是，抬升必须由板块边界力所允许，并受岩石圈结构中预先存在的不均匀性的影响。最好的例子是大西洋，其大规模的几何形状与三个大盆地是由三个地幔柱的影响点。(C)1999 Elsevier Science B. V.保留所有权利。
Temporal coincidence between continental flood basalts and breakup has been noted for almost three decades. Eight major continental flood basalts have been produced over the last 300 Ma. The most recent, the Ethiopian traps, erupted in about 1 Myr at 30 Ma. Rifting in the Red Sea and Gulf of Aden, and possibly East African rift started at about the same time. A second trap-like episode occurred around 2 Ma and formation of true oceanic crust is due in the next few Myr. We find similar relationships for the 60 Ma Greenland traps and opening of the North Atlantic, 65 Ma Deccan traps and opening of the NW Indian Ocean, 132 Ma Parana traps and South Atlantic, 184 Ma Karoo traps and SW Indian Ocean, and 200 Ma Central Atlantic Margin flood basalts and opening of the Central Atlantic Ocean. The 250 Ma Siberian and 258 Ma Emeishan traps seem to correlate with major, if aborted, phases of rifting. Rifting asymmetry, apparent triple junctions and rift propagation (towards the flood basalt area) are common features that may, together with the relative timings of flood basalt, seaward dipping reflector and oceanic crust production, depend on a number of plume- and lithosphere- related factors. We propose a mixed scenario of 'active/passive' rifting to account for these observations. In all cases, an active component (a plume and resulting flood basalt) is a pre-requisite for the breakup of a major oceanic basin. But lifting must be allowed by plate-boundary forces and is influenced by pre-existing heterogeneities in lithospheric structure. The best example is the Atlantic Ocean, whose large-scale geometry with three large basins was imposed by the impact points of three mantle plumes. (C) 1999 Elsevier Science B.V. All rights reserved.