History of scoria-cone eruptions on the eastern shoulder of the Kenya-Tanzania Rift revealed in the 250-ka sediment record of Lake Chala near Mount Kilimanjaro
History of scoria-cone eruptions on the eastern shoulder of the Kenya-Tanzania Rift revealed in the 250-ka sediment record of Lake Chala near Mount Kilimanjaro
复制标题
乞力马扎罗山附近查拉湖 250ka 沉积物记录揭示了肯尼亚-坦桑尼亚裂谷东肩火山渣锥喷发的历史
DOI：
10.1002/jqs.3140
复制
发表时间：
2019
影响因子：
2.3
通讯作者：
Martin-Jones C
中科院分区：
文献类型：
--
作者：
Martin-Jones C
重建过去喷发的时间和频率对于评估未来火山活动的倾向很重要，但在东非裂谷等火山区，只存在零星的喷发历史。了解珊瑚锥体油田的火山史尤其具有挑战性，因为那里的火山喷发往往很少见，沉积物受到强烈的风化。在这里，我们利用乞力马扎罗山附近查拉湖约250-ka的沉积记录中保存的一系列火山灰(火山灰)层，从位于肯尼亚-坦桑尼亚裂谷东部肩部的火山锥重建了火山活动的历史。根据玻璃化学、结构特征和已知的喷发年代学，查拉湖序列中的七个可见和两个不可见(隐蔽)的盖夫拉层被归因于乞力马扎罗山(坦桑尼亚北部)和丘鲁山(肯尼亚南部)火山田的活动。Chala湖记录的Chala火山喷发记录证实了其近期活动的地质和历史证据，并提供了七次以前未知的喷发的一级年龄估计。
Reconstructions of the timing and frequency of past eruptions are important to assess the propensity for future volcanic activity, yet in volcanic areas such as the East African Rift only piecemeal eruption histories exist. Understanding the volcanic history of scoria‐cone fields, where eruptions are often infrequent and deposits strongly weathered, is particularly challenging. Here we reconstruct a history of volcanism from scoria cones situated along the eastern shoulders of the Kenya–Tanzania Rift, using a sequence of tephra (volcanic ash) layers preserved in the ~250‐ka sediment record of Lake Chala near Mount Kilimanjaro. Seven visible and two non‐visible (crypto‐) tephra layers in the Lake Chala sequence are attributed to activity from the Mt Kilimanjaro (northern Tanzania) and the Chyulu Hills (southern Kenya) volcanic fields, on the basis of their glass chemistry, textural characteristics and known eruption chronology. The Lake Chala record of eruptions from scoria cones in the Chyulu Hills volcanic field confirms geological and historical evidence of its recent activity, and provides first‐order age estimates for seven previously unknown eruptions. Long and well‐resolved sedimentary records such as that of Lake Chala have significant potential for resolving regional eruption chronologies spanning hundreds of thousands of years.