Structural evolution of the Pleistocene Cimini trachytic volcanic complex (Central Italy)
Structural evolution of the Pleistocene Cimini trachytic volcanic complex (Central Italy)
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DOI：
10.1007/s00445-005-0028-3
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发表时间：
2006-05-01
影响因子：
3.5
通讯作者：
De Rita, D
中科院分区：
文献类型：
--
作者：
Cimarelli, C;De Rita, D
已处理了结构、地貌、地球物理和火山学数据，以建立一个专门的地理信息系统，通过该系统重建了更新世粗面岩Cimini火山（意大利中部）的结构演变。Cimini杂岩的演化经历了3个主要的近场阶段：（1）浅部岩盖侵入，沿着NW和NE向断裂上升，并停滞在构成火山基岩的中新生代和上新世-更新世沉积单元之间的接触处：（2）沿岩盖生长引起的膨胀形成的径向和切向裂隙侵位熔岩穹丘;（3）熔结凝灰岩喷发和橄榄-粗晶熔岩的最终喷出。穹丘类型有火山穹丘和低熔岩穹丘两种，其形态受隆起区斜面位置的控制。一些圆顶显示有隆起的上新世热变质粘土沉积物，这表明一个隐圆顶状的增长。中新生代单元顶部与上新世-更新世沉积杂岩顶部的对比表明，岩帽侵位在中新生代沉积杂岩的地堑中，被浅侵入体抬升的上新世-更新世沉积物充填。通过分析水系网络和构造地貌，推导出了作用于Cimini地区的应力模式。玫瑰图显示了一个大的分散的线性反映当地存在的径向和切向断裂。最常见的北西和北东向伸展线性构造具有区域意义，并控制了导致岩盖侵位的岩浆上升。
Structural, geomorphological, geophysical and volcanological data have been processed for the implementation of a dedicated GIS through which the structural evolution of the Pleistocene trachytic Cimini volcano (central Italy) has been reconstructed. The evolution of the Cimini complex includes three main close-in time phases: (1) intrusion of a shallow laccolith, rising along NW and NE trending faults and stagnating at the contact between the Mesozoic-Cenozoic and the Pliocene-Pleistocene sedimentary units constituting the bedrock of the volcano; (2) emplacement of lava domes along radial and tangential fractures formed by the swelling induced by the laccolith growth; (3) ignimbrite eruptions and final effusion of olivine-latitic lavas. Domes are both of Pelean and low lava dome type and their morphology was controlled by the location on the inclined surface of the swelled area. Some domes show to have uplifted upper Pliocene thermally metamorphosed clay sediments, suggesting a cryptodome-like growth. Comparison of the top of the Mesozoic-Cenozoic units with the top of the upper Pliocene-Pleistocene sedimentary complex, suggests that the laccolith emplaced in a graben of the Mesozoic-Cenozoic sedimentary complex filled by the Pliocene-Pleistocene sediments uplifted by the shallow intrusion. Stress patterns acting on the Cimini area have been deduced analysing the drainage network and the morphotectonic lineaments. Rose diagrams show a large dispersion of the lineaments reflecting the local presence of radial and tangential fractures. The most frequent extensional NW and NE trending lineaments have regional significance and controlled the magma uprise leading to the laccolith emplacement.