Petrological, Geochemical, and Statistical Analysis of Eocene–Oligocene Sandstones of the Western Thrace Basin, Greece and Bulgaria
Petrological, Geochemical, and Statistical Analysis of Eocene–Oligocene Sandstones of the Western Thrace Basin, Greece and Bulgaria
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DOI：
10.2110/jsr.2012.31
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发表时间：
2012-07
影响因子：
2
通讯作者：
L. Caracciolo;H. Eynatten;R. Tolosana-Delgado;S. Critelli;P. Manetti;P. Marchev
中科院分区：
文献类型：
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作者：
L. Caracciolo;H. Eynatten;R. Tolosana-Delgado;S. Critelli;P. Manetti;P. Marchev
摘要 罗多匹造山带自晚白垩世至早始新世以来，在新特提斯洋分支瓦尔达尔洋盆闭合后的增生过程中形成。通过多学科方法，包括砂岩岩石学以及碎屑和火山碎屑沉积物的地球化学，我们重建了罗多比造山带的揭顶历史，并描述了希腊和保加利亚色雷斯盆地西部地区晚始新世和渐新世之间的形成和演化特征。 127 个砂岩样本的碎屑模式提供了三种独特岩相的证据：石英岩、石英长岩和火山碎屑岩。岩相成分证明了来自对应于三个主要构造单元的三个关键源区的贡献：环罗多辉带、杂色杂岩（超镁铁杂岩）和片麻岩-混合岩杂岩。这三种岩相反映了不同构造环境的多种物源，从石英石岩演化到石英长石岩再到火山碎屑岩，分别对应于碰撞造山带、地壳隆起和火山弧环境。主要元素和微量元素的地球化学数据用于讨论构造背景判别图的有效性，并将其与狄金森模型进行比较，以及区分和表征（i）岩石学上均质的片麻岩提供的次盆地和（ii）火山对砂岩成分的贡献。多元统计技术用于揭示控制沉积物成分的复杂因素网。双图分析强调了两个独立过程的影响：(1) 碳酸盐相和硅酸盐相之间的混合，以及 (2) 从镁铁质烃源岩到长英质烃源岩的演化。后者表明地壳深处的供应率逐渐增加。希腊东北部和保加利亚东南部色雷斯盆地砂岩套的成分演化与罗多彼地区的各个地球动力学阶段密切相关。色雷斯砂岩的物源分析提供了造山带砂相关盆地随时间变化的性质的示例，并且可能有助于对类似地球动力学环境的一般理解。
Abstract The Rhodopian Orogen developed since the Late Cretaceous–early Eocene during accretionary processes following the closure of the Vardar ocean basin, a branch of Neotethys. Through a multidisciplinary approach, including sandstone petrology and geochemistry of the clastic and volcanoclastic sediments, we reconstruct the unroofing history of the Rhodopian orogen and characterize the formation and the evolution of the western portions of the Thrace basin, in Greece and Bulgaria, between the late Eocene and Oligocene. Detrital modes of 127 sandstone samples provide evidence of three distinctive petrofacies: quartzolithic, quartzofeldspathic, and volcanoclastic. The petrographic composition gives evidence of contributions from three key source areas corresponding to the three main tectonic units: the Circum-Rhodope Belt, the Variegated Complex (ultramafic complex), and the Gneiss–Migmatite Complex. The three petrofacies reflect multiple provenance from different tectonic settings as they evolve from quartzolithic to quartzofeldspathic to volcanoclastic, corresponding to collisional orogen, crustal block uplift, and volcanic arc settings, respectively. Geochemical data on major elements and trace elements are used to discuss the efficacy of tectonic-setting discrimination diagrams and compare them to the Dickinson model as well as to distinguish and characterize (i) petrographically homogeneous gneiss-supplied subbasins and (ii) volcanic contributions to sandstone composition. Multivariate statistical techniques are used to unravel the complex web of factors controlling sediment composition. Biplot analysis highlights the influence of two independent processes: (1) mixing between carbonate and silicate phases, and (2) evolution from mafic to felsic source rocks. The latter indicates progressively increasing supply rates from deeper crustal levels. The compositional evolution of the sandstone suites of Thrace basin in NE Greece and SE Bulgaria is strictly related to various geodynamic stages of the Rhodope region. Provenance analysis of Thrace sandstones provide an example of the changing nature of orogenic belt sand associate basins through time, and may contribute to the general understanding of similar geodynamic settings.