C. Benavente, S. Matheos, S. Barredo, F. Abarzúa, A. Mancuso
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引用次数: 0
Abstract
The lithostratigraphic units that conform the Sorocayense Group and fill the Sorocayense-Hilario sub-basin represent an alluvial-fluvial-lacustrine succession with significant volcanic supply during its deposition. They are namely the Cerro Colorado del Cementerio, Agua de los Pajaritos, Monina, Hilario and El Alcázar formations and present several carbonate levels. The genesis, diagenesis, and main controlling factors on continental carbonates present a means to understand basin evolution through the study of their petrography and chemical elemental composition through cathodoluminescence techniques. We have identified six microfacies: a) homogeneous micrite, b) bioclastic micrite, c) dolomicrite, d) laminated micrite, e) oncolitic packstone, and f) sparitic carbonate. Among these microfacies, six cementation and alteration phases have been identified: a) micritization, b) mechanical compaction, c) calcitic cementation, d) sparitic cementation, e) microsparitic cementation, and f) chemical compaction. This analysis allowed establishing a chronology of the diagenetic modifications undergone by the carbonates. Results support diagenesis was controlled mainly by tectonics showing major impact in carbonate facies identified at the flexural margin of the rift. The effect would have been linked to exertion of a paleohydrological effect favoring lateral meteoric water migration through faulting. The presence of dolomite in some of the microfacies is linked to the presence of montmorillonite as the dominant Mg-rich-phyllosilicate in clay assemblages most likely acting as the potential source. In turn, Mg is more likely to be replaced by Mn leading to luminescent carbonate microfacies.
整合索罗卡色岩群和充填索罗卡色岩群-希拉里奥亚盆地的岩石地层单元代表了一个冲积-河流-湖泊序列,其沉积过程中有大量的火山补给。它们分别是Cerro Colorado del Cementerio、Agua de los Pajaritos、Monina、Hilario和El Alcázar地层,并呈现出几个碳酸盐层。陆相碳酸盐岩的成因、成岩作用及其主控因素为利用阴极发光技术研究其岩石学和化学元素组成提供了了解盆地演化的手段。我们确定了6种微相:a)均质泥晶,b)生物碎屑泥晶,c)白云泥晶,d)层状泥晶,e)块状泥晶,f)空间质碳酸盐。在这些微相中,确定了6个胶结和蚀变阶段:a)泥晶化,b)机械压实,c)钙化胶结,d)空间胶结,e)微空间胶结,f)化学压实。通过这种分析,可以建立碳酸盐岩成岩作用变化的年表。结果表明成岩作用主要受构造控制,主要影响于裂谷弯曲边缘的碳酸盐岩相。这种影响可能与古水文作用的发挥有关,这种作用有利于通过断层的横向大气水迁移。在某些微相中白云岩的存在与蒙脱石的存在有关,蒙脱石是粘土组合中主要的富镁层状硅酸盐,最有可能是潜在的来源。镁更容易被锰取代,形成发光碳酸盐微相。
期刊介绍:
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.