The Mato Perso Conduit System: evidence of silicic magma transport in the southern portion of the Paraná-Etendeka LIP, Brazil
The Mato Perso Conduit System: evidence of silicic magma transport in the southern portion of the Paraná-Etendeka LIP, Brazil
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马托佩尔索管道系统：巴西巴拉那-埃滕德卡 LIP 南部地区硅质岩浆输送的证据
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发表时间：
2018
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通讯作者：
L. Rossetti
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作者：
M. S. Simões;E. F. Lima;C. Sommer;L. Rossetti
Mato Perso管道系统位于巴西南部约120 km 2的区域，暴露了Parana-Etendeka LIP的火山岩。火山序列由玄武岩流定义，玄武岩流被平坦的氧化玻璃斑岩、切割下部熔岩的带状玻璃斑岩和覆盖所有单元的灰色平坦玻璃斑岩覆盖。流动形态确定的结构，纹理和囊泡分布的识别进行了观察。氧化玻璃斑岩显示出巨大的扁平带状核心和从泡状到泡沫状的流动顶部。在玄武岩流和氧化玻璃斑岩的顶部，灰色的平卧玻璃斑岩有尖锐的接触，局部显示基底角砾岩，并有平卧叶理。管道以带状玻璃斑岩和角砾岩为代表，这些玻璃斑岩和角砾岩在一个6 km宽的NW-SE向段中出露，该段被正断层向下抛向Antas河。在地质图比例尺上对这些单元的解释表明了侵入接触关系。条带状玻璃斑岩和氧化玻璃斑岩脉中脉状构造的识别是长英质岩浆搬运的证据。根据野外观测，我们提出了由断层相关管道系统供给的陆上氧化和灰色玻璃斑岩的就位。持续的高温岩浆系统确保了熔岩具有低粘度和长距离的移动。
The Mato Perso Conduit System is described from a ~ 120 km2 area in south Brazil exposing silicic volcanics of the Parana-Etendeka LIP. A volcanic succession is defined by basaltic flows covered by flat-lying oxidized vitrophyres, banded vitrophyres cutting the lower lavas and grey flat-lying vitrophyres covering all the units. Flow morphologies determined by the recognition of structures, textures, and vesicle distribution were observed. Oxidized vitrophyres display massive flat-lying banded cores and flow tops from vesicular to frothy. Grey flat-lying vitrophyres have sharp contacts in the top of both basalt flows and oxidized vitrophyres, locally exhibit basal breccia and have a flat-lying foliation. Conduits are represented by banded vitrophyres and breccias, which outcrop in a 6 km wide, NW-SE oriented segment downthrown by normal faults towards the Antas River. The interpretation of the units on the geological map scale indicates intrusive contact relations. Recognition of dike-like structures in banded vitrophyres and dykes of oxidized vitrophyre are evidence of felsic magma transport. Based on field observations, we propose the emplacement of subaerial oxidized and grey vitrophyres fed by a fault-related conduit system. Sustained high temperature magmatic systems ensure the silicic lavas have a low viscosity and travel great distances.