Growth and dispersal of a southeast African large igneous province
Growth and dispersal of a southeast African large igneous province
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东南非洲大型火成岩省的生长和扩散
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Nicole Grobys
中科院分区：
文献类型：
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作者：
K. Gohl;G. Uenzelmann‐Neben;Nicole Grobys
莫桑比克海脊（MOZR）和阿古拉斯高原（AP）是非洲东南部海域的突出的水深升高的隆起，与水深表达较少的隆起相连。直觉上，这一观察结果意味着高原和隆起经历了一个相关的地壳形成过程。深部地壳海底地震仪数据和多通道地震反射剖面从南部MOZR显示其主要是海洋地壳起源与过度的火山喷发和岩浆增生阶段的证据。地壳柱的下三分之二显示出P波速度大于7.0 km/s，增加到7.5至1.5 km/s。
7.6 km/s在地壳底部。这些速度表明，下地壳是由大量的幔源物质增生形成的，相当于海洋层3。MOZR的速度-深度模型和地震反射数据与AP的相似，这表明一个更大的东南非洲大火成岩省（LIP）必须在140至95 Ma之间形成，处于高度变化的岩浆和火山活动阶段。东南非洲LIP的时间，规模和形成历史与Kerguelen-Heard高原相似，这引起了对当时幕式岩浆生成相关过程的猜测。
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.