J. A. Murra, Edgardo G. Baldo, Sebastián O. Verdecchia, Carlos D. Ramacciotti, C. Galindo
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引用次数: 0
摘要
El Escorial大理岩（Cushamen变质杂岩）和角闪岩在Mamil Choique组（261-286 Ma）的二叠纪花岗岩中形成变质隔膜。变质作用发生在El Escorial西南120km的麻粒岩相混合片麻岩中，发生在311±27Ma（独居石中的CHIME方法）。大理石为钙质（方解石>95%，R.I.：0.5至2.5%），87Sr/86Sr值在0.70768至0.70825之间（n=10）。这项工作中提供的数据，加上之前的贡献，可以将库沙门变质杂岩的硅化碳酸盐序列的沉积年龄限制在约385至335 Ma之间。这表明至少在中泥盆纪和早石炭世（中密西西比纪）之间的冈瓦纳大陆西南部最南部存在混合碳酸盐-硅碎屑台地。
Los mármoles cálcicos de El Escorial (Complejo Metamórfico Cushamen, Macizo Norpatagónico): caracterización isotópica de 87Sr-86Sr y edad de sedimentación
The El Escorial marbles (Cushamen Metamorphic Complex) along with amphibolites form metamorphic septa within the permian granitoids of the Mamil Choique Formation (261-286 Ma). The metamorphism, determined in granulite facies migmatic gneisses septa cropping out 120 km southwest of El Escorial, occurs at 311 ± 27 Ma (CHIME method in monazite). The marbles are calcitic (calcite > 95%, R.I.: 0.5 to 2.5%) and show 87Sr/86Sr values between 0.70768 and 0.70825 (n = 10). The data provided in this work, added to previous contributions, allow to constraints the sedimentation age of the silicic-carbonate successions of the Cushamen Metamorphic Complex between ca. 385 and 335 Ma. This suggests the existence of a mixed carbonate-siliciclastic platform at least in the southernmost portion of southwestern Gondwana between Middle Devonian and early Carboniferous (Middle Mississippian).
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This journal publishes original and review articles on geology and related sciences, in Spanish or English, in three issues a year (January, May and September). Articles or notes on major topics of broad interest in Earth Sciences dealing with the geology of South and Central America and Antarctica, and particularly of the Andes, are welcomed.
The journal is interested in publishing thematic sets of papers and accepts articles dealing with systematic Paleontology only if their main focus is the chronostratigraphical, paleoecological and/or paleogeographical importance of the taxa described therein.
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