Problems and challenges in detection of pre-Mesozoic maar volcanoes: example from the Principalek Volcano in the Permian Krkonose Piedmont Basin
Problems and challenges in detection of pre-Mesozoic maar volcanoes: example from the Principalek Volcano in the Permian Krkonose Piedmont Basin
复制标题
前中生代玛珥火山探测中的问题和挑战：以二叠纪克尔科诺斯皮埃蒙特盆地普林尼莱克火山为例
DOI：
10.3190/jgeosci.170
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发表时间：
2014
影响因子：
1.4
通讯作者：
J. Balek
中科院分区：
文献类型：
--
作者：
J. Valenta;V. Rapprich;M. Stárková;Z. Skácelová;L. Fojtíková;F. Staněk;J. Balek
采用地质填图和地球物理方法，对捷克Vrchlabi西南部Principalek山的二叠系火山碎屑矿床进行了研究。火山碎屑岩暴露在几个小的连贯露头中，但许多解释都是基于碎屑。保存下来的纹理能够重建喷发的样式。火山活动开始于由细粒凝灰岩和底部的增生石所记录的呼吸岩浆喷发。随后，活动转变为俯冲-斯特隆堡/苏尔特采扬活动，产生金凤钻凝灰岩和金凤钻酮。这些事件之后是斯特隆波利期，以火山弹状碎屑凝灰岩角砾岩分类不清为证据。最上面的单元由焊接的熔岩凝集物和玄武岩熔岩组成，表明是夏威夷式的喷发。其中一个玄武岩喂养颈暴露在一个小的废弃采石场。对火山碎屑沉积的范围进行了地球物理调查。这些方法包括重力测量、磁力测量和直流电阻率层析成像。磁资料表明，火山碎屑矿床中部存在玄武岩脉。直流电层析成像证实了岩脉的存在，估算了火山碎屑沉积厚度，并为岩浆裂缝的大小和位置提供了证据。重力数据显示，与硅藻土有关的岩石密度较低，这可能是硅藻土与乡村岩石之间岩石密度对比较低的结果。我们认为这与沉积与火山活动的时间间隔较短有关，也与岩石圈与周围围岩的联合埋藏和成岩历史有关。
The Permian pyroclastic deposits on the Principalek Hill SW of Vrchlabi (Czech Republic) were investigated by means of geological mapping and geophysics. The pyroclastic rocks are exposed in several small coherent outcrops, yet many interpretations are based on debris. The preserved textures enable reconstruction of eruptive styles. The volcanism started with phreatomagmatic eruptions documented by the fine-grained tuff with accretionary lapilli at the base. Subsequently, the activity changed to phreato-Strombolian/Surtseyan producing lapilli-tuffs and lapillistones. These events were followed by a Strombolian phase as evidenced by ill-sorted scoriaceous tuff-breccias with volcanic bombs. The uppermost unit consists of welded lava agglutinates and basaltic lavas suggesting a Hawaiian style of eruption. One of the basaltic feeder necks is exposed in a small abandoned quarry. Geophysical surveys were carried out over the extent of pyroclastic deposits. These included gravimetry, magnetometry, and DC resistivity tomography. The magnetic data indicate the occurrence of basaltic dykes in the central part of the pyroclastic deposits. The DC tomography confirms the presence of dykes, enables estimation of the pyroclastic deposits thickness, and provides evidence for the size and position of the maar-diatreme. Gravity data yield an insignificant low associated with the diatreme, which is likely a product of low rock-density contrast between the diatreme and country rocks. We argue that this is due to short time gap between sedimentation and volcanic activity and also related to conjoint burial and diagenetic history of the diatreme and the surrounding country rocks.
德国西萨克森州埃伯斯布伦大区磁异常的起源
影响因子：
3.5
作者：
Schmidt;Nowaczyk;Kämpf;Schüller;Flechsig
通讯作者：
Flechsig