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首页> 外文期刊>Journal of Volcanology and Geothermal Research >On the use of unconformities in volcanic stratigraphy and mapping: Insights from the Aeolian Islands (southern Italy)
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On the use of unconformities in volcanic stratigraphy and mapping: Insights from the Aeolian Islands (southern Italy)

机译：关于不整合在火山岩地层和制图中的使用：风神群岛（意大利南部）的见解

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The approach to volcanic stratigraphy and mapping in the Aeolian Islands has found the concept of Unconformity-Bounded Units (UBUs) extremely useful for purposes of stratigraphic classification and correlation. Volcanic unconformities (erosive and collapse unconformities) relative to processes of internal modification of a volcano are classified separately from sea level-driven unconformities. The erosive unconformities formed during periods of volcanic quiescence are generally characterized by angular relationships and lithological change between the products below and above an unconformity, and may be associated with paleosols or epiclastic horizons. The collapse unconformities related to calderas and lateral collapses represent surfaces of structural truncation along the collapse borders, passing outside of the collapse to erosive unconformities developed during the corresponding repose periods. Instead, the sea level-driven unconformities are marine and subaerial erosive surfaces bounding in pairs the depositional cycles relative to sea level highstands, which are recorded in raised marine terraces. Most unconformities can be correlated on a variable scale from local (volcanic island) to regional (inter-island) by means of careful stratigraphic analysis targeted to identify the corresponding stratigraphic hiatus in the volcanic successions in different points of observation. This helps to solve the problems arising from the difficult recognition of the unconformities in the field moving away from the type locality due to their variable features. A practical nomenclature scheme for a hierarchy of UBUs to be applied in volcanic areas can be established on the basis of the areal magnitude of the bounding unconformities and their importance in the volcano history, passing through a slight modification of the International Stratigraphic Guide's rules. Combined with lithostratigraphic units (mapped rock bodies) and lithosomes (eruptive centres), the UBUs provide a useful stratigraphic synthesis of a volcanic area by means of a framework of time-stratigraphic unconformable surfaces. Moreover, UBUs can be directly interpreted in terms of volcanic activity units with a time-stratigraphic significance, thus providing the key elements for the eruptive history of a volcano and the definition of its event stratigraphy. (C) 2019 Published by Elsevier B.V.
机译：风成群岛的火山地层和制图方法发现，不整合边界单元（UBU）的概念对于地层分类和相关性极为有用。相对于火山内部修改过程，火山不整合（侵蚀和塌陷不整合）与海平面驱动的不整合分开分类。火山静止期间形成的侵蚀性不整合面通常以不整合面上下之间的产品之间的角度关系和岩性变化为特征，并且可能与古土壤或表层碎屑岩有关。与破火山口和侧向塌陷有关的塌陷不整合面代表沿塌陷边界的结构截断面，在塌陷的外部传递到在相应的休养期期间形成的侵蚀不整合面。相反，海平面驱动的不整合面是成对界定相对于海平面高位的沉积周期的海洋和地下侵蚀表面，这些沉积周期记录在凸起的海洋阶地中。可以通过仔细的地层分析来确定大多数不整合面，从局部（火山岛）到区域（岛间），以识别不同观测点的火山演替中相应的地层裂隙。这有助于解决由于难以识别由于其可变特征而远离类型局部性的领域中的不合格所引起的问题。通过略微修改《国际地层学指南》的规则，可以根据边界不整合面的面积大小及其在火山历史中的重要性，为在火山区中应用的UBU等级建立实用的命名法。与时间地层不整合面的框架相结合，UBU与岩石地层学单元（映射的岩石体）和岩石小体（火山喷发中心）相结合，为火山区提供了有用的地层综合。此外，可以用具有时间地层意义的火山活动单位直接解释UBU，从而为火山的爆发历史及其事件地层的定义提供关键要素。 （C）2019由Elsevier B.V.发布

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