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首页> 外文期刊>Journal of Volcanology and Geothermal Research >The relationship between Late Quaternary deformation and volcanism of Mt. Etna (eastern Sicily): new evidence from the sedimentary substratum in the Catania region
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The relationship between Late Quaternary deformation and volcanism of Mt. Etna (eastern Sicily): new evidence from the sedimentary substratum in the Catania region

机译：第四纪晚第四纪变形与火山活动的关系。埃特纳火山（西西里岛东部）：卡塔尼亚地区沉积层的新证据

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摘要

Stratigraphical and structural analyses have been carried out on the Late Quaternary foredeep succession forming the Etnean substratum in the Catania region (eastern Sicily), in order to investigate in detail the chronology of deformation events that have accompanied a significant period of the eruptive activity of Mt. Etna, i.e. from 240 ka to the Present. This episode was characterised, at about 200 ka, by a main change of the petrochemical features of the emitted products from sub-alkaline to alkaline. This can be related to an evolving mantle diapir located beneath the volcano. The new Stratigraphical and structural field data, presented in this paper, constrain the development, from 240 to 125 ka, of NW-SE-trending dextral faults associated with minor E-W- to NE-SW-oriented accommodation thrusts and NNW-SSE-trending normal faults that originated in a dominant transpressive regime. Strike-slip tectonics were active during the earlier emissions of sub-alkaline lavas (320-200 ka old) and part of the ancient alkaline products (180-100 ka old), from scattered eruptive systems which developed in local transtensive zones, distributed throughout the whole Etnean region. A major change in the mode of deformation, since 125 ka BP, was related to the propagation of a normal fault belt along the Ionian coast of the Catania region and the eastern sectors of the Etnean edifice. This process was associated with the growth of open folds that deformed the entire foredeep sequence exposed along the southern boundary of the Etnean edifice. During this period, eruptive activity concentrated along the main extensional features where steady and very efficient feeding systems originated. This resulted in a rapid increase in the volume of emitted alkaline products that gave rise to the construction of the modern stratovolcano during the last 80 ka. The collected data emphasise some main aspects of the relationship between tectonic deformation at a regional scale and volcanism in the Etna area. Firstly, the mode of deformation at the onset of Etnean volcanism seems to be inadequate to explain the emplacement at depth of a mantle diapir related to the occurrence of a hotspot, almost independent from the local crustal dynamics. On the other hand, the Late Quaternary structural assemblages recognised on the surface can be interpreted as direct effects of the Europe-Africa convergence, rather than as the products of deformation induced by the emplacement of the mantle diapir. In the different stages of Etnean evolution a direct relationship exists between the mode of deformation and the distribution as well as the capacity of the feeding systems. In particular, the amounts of emitted products in the different stages depend on the intensity of crustal stretching associated with deformation, rather than the volume of available molten material at depth. These conclusions represent a new perspective for the interpretion of the early stages and subsequent evolution of the volcanic activity of Mt. Etna. The proposed model also represents an useful tool in deciphering the relationship between the deformation path, seismicity and volcanic activity of Mt. Etna.
机译：在卡塔尼亚地区（西西里岛东部）形成第四纪的埃特尼亚基底的第四纪晚期前陆深层演替中，已经进行了地层和结构分析，目的是详细调查伴随着火山爆发活动的重要时期的变形事件的时间顺序。 。埃特纳火山，即从240 ka到现在。该事件的特征是，在大约200 ka时，排放物的石油化学特征从次碱性变为碱性，这是主要变化。这可能与位于火山下方的地幔底盘发育有关。本文介绍的新的地层和构造场数据将与NW-SE向右旋断层的发展从240 ka扩展到125 ka，这与较小的EW-向NE-SW导向的适应推力和NNW-SSE向相关正常的断层起源于显性压性机制。早期的亚碱性熔岩（320-200 ka年）和部分古代碱性产物（180-100 ka年）的早期散逸活动是走滑构造运动的产物，这些散发的喷发系统是在局部发散带发育的，分布在整个整个Etnean地区。自从125 ka BP以来，变形模式的主要变化与正常断层带沿卡塔尼亚地区的爱奥尼亚海沿岸和埃特尼大厦的东部传播有关。该过程与开放褶皱的生长有关，该褶皱使沿埃特尼大厦的南边界暴露的整个前深层序列变形。在此期间，爆发活动集中在主要的伸展特征上，而稳定和非常有效的饲养系统起源于此。这导致排放的碱性产物量迅速增加，这导致了最近80 ka期间建造的现代平流层火山。收集到的数据强调了区域规模的构造变形与埃特纳火山地区火山活动之间关系的一些主要方面。首先，埃特纳火山爆发时的变形模式似乎不足以解释与热点发生有关的地幔底盘深处的位移，这几乎与当地地壳动力学无关。另一方面，表面上公认的第四纪晚期构造组合可以解释为欧洲-非洲融合的直接影响，而不是由地幔底辟的进入引起的形变产物。在Etnean演化的不同阶段，变形模式与分布以及进料系统的容量之间存在直接关系。特别地，在不同阶段中排出的产物的量取决于与变形相关的地壳伸展的强度，而不是取决于深度处可用熔融材料的量。这些结论为解释Mt火山活动的早期阶段和随后的演化提供了新的视角。埃特纳火山。所提出的模型还代表了一个有用的工具，可用来解释山的变形路径，地震活动性和火山活动之间的关系。埃特纳火山。

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