Redefinicion de la formacion farellones en la Cordillera de los Andes de Chile Central (32-34°S)
Redefinicion de la formacion farellones en la Cordillera de los Andes de Chile Central (32-34°S)
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智利中部 (32-34°S)
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
R. Villarroel
中科院分区：
文献类型：
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作者：
S. Rivano;E. Godoy;M. Vergara;R. Villarroel
摘要。根据在阿空加瓜谷北部Cerro拉格洛里亚北方侧出露的一个新的、更完整的参考地层剖面，提出了Farellones组的重新定义。这个新的参考剖面和暴露在Farellones的修改剖面现在应被视为地层的复合层型。重新定义的Farellones组包括一个下部流纹英安岩凝灰质至熔结凝灰岩段，以及一个由玄武安山岩组成的上部段，由流纹英安岩穹隆侵入。前者可能与破火山口型喷发有关，而后者则代表了成层火山的熔岩流和火山灰的相互作用。在南纬33°和34°之间，地层的露头仅限于其上段，就像Farellones地区的情况一样。在那个地方，以前的作者包括蚀变流和火山碎屑岩，可以对应于Abanico组，下段没有代表。
ABSTRACT. Based on a new and more complete reference stratigraphic section exposed at the northern flank of Cerro La Gloria, north of the Aconcagua valley, a redefinition of the Farellones Formation is proposed. This new reference section and the modified section exposed at Farellones should now be considered the composite stratotype of the formation. As redefined the Farellones Formation includes a lower, rhyolitic-dacitic, tuffaceous to ignimbritic member, and an upper member made up of basaltic andesites, intruded by rhyodacitic domes. While the former is probably related to caldera-type eruptions, the latter represents an interfingering of flows and tephra from stratovolcanoes. Between parallels 33° and 34°S the outcrops of the formation are restricted to its upper member, as is the case in the Farellones area. At that locality, where previous authors included altered flows and pyroclastic rocks that could correspond to the Abanico Formation, the lower member is not represented.