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首页> 外文期刊>South African Journal of Geology: Being the Transaction of the Geological Society of South African: Syndie die Verhandelinge van die Geologiese Vereniging van Suid-Afrika >GROWTH AND DISPERSAL OF A SOUTHEAST AFRICAN LARGE IGNEOUS PROVINCE
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GROWTH AND DISPERSAL OF A SOUTHEAST AFRICAN LARGE IGNEOUS PROVINCE

机译：东南非洲大火成岩省的生长和分布

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摘要

The Mozambique Ridge (MOZR) and the Agulhas Plateau (AP) are prominent bathymetrically elevated rises off south-eastern Africa connected by a rise of less bathymetric expression. Intuitively, this observation would imply that the plateaus and rises underwent a related crustal formation. Deep crustal ocean-bottom seismometer data and a multichannel seismic reflection profile from the southern MOZR show evidence for its predominantly oceanic crustal origin with excessive volcanic eruption and magmatic accretion phases. The lower two-thirds of the crustal column exhibit P-wave velocities of more than 7.0 km/s, increasing to 7.5 to 7.6 km/s at the crustal base. These velocities suggest that the lower crust was accreted by large volumes of mantle-derived material to form an over-thickened equivalent of an oceanic layer 3. The velocity-depth model and the seismic reflection data of the MOZR resemble those of the AP, which suggests that a greater Southeast African Large Igneous Province (LIP) must have formed between 140 and 95 Ma in phases of highly varying magmatic and volcanic activities. The timing, size, and formation history of the Southeast African LIP is similar to those of the Kerguelen-Heard Plateau, which invites speculation about related processes of episodic magma generation at that time.
机译：莫桑比克海岭（MOZR）和阿古拉斯高原（AP）是南部非洲南部东南部的一个以等轴测图表示的上升而突出的等轴测图升高的上升。凭直觉来看，这种观察暗示着高原和上升经历了相关的地壳形成。深部地壳海底地震仪数据和来自MOZR南部的多通道地震反射剖面显示了其主要为海洋地壳起源，火山喷发和岩浆增生阶段过多的证据。地壳柱下部的三分之二显示出P波速度超过7.0 km / s，在地壳基础处增加到7.5至7.6 km / s。这些速度表明，下地壳会被大量的地幔衍生物质所吸收，从而形成了海洋层3的超厚等效物。MOZR的速度-深度模型和地震反射数据类似于AP的速度-深度模型和地震反射数据。这表明，在岩浆和火山活动高度变化的阶段中，必须在140至95 Ma之间形成更大的东南非洲大火成岩省（LIP）。东南部LIP的时间，规模和形成历史与Kerguelen-Heard高原的相似，这引起了关于当时岩浆形成的相关过程的推测。

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