Investigation of Deep-Sea Volcanic Ash Layers from Equatorial Pacific Cores
Investigation of Deep-Sea Volcanic Ash Layers from Equatorial Pacific Cores
复制标题
赤道太平洋核心的深海火山灰层调查
DOI：
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发表时间：
1973
期刊：
影响因子：
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通讯作者：
I. Carmichael
中科院分区：
文献类型：
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作者：
F. Bowles;R. N. Jack;I. Carmichael
对取自赤道东部和东南太平洋的 56 个岩心的 128 个火山灰样本进行痕量和微量元素分析，可以识别和关联海底广阔区域的各个火山灰层。已经划定了火山灰沉积的三个主要地区，可能的来源地区是危地马拉、萨尔瓦多、尼加拉瓜、哥伦比亚或厄瓜多尔。对大陆浮石样本的分析表明，危地马拉高地特克潘-奇马尔特南戈盆地和萨尔瓦多伊洛潘戈湖地区附近有喷口。许多（或许是全部）火山灰层的历史都不超过 30 万年。两个最广泛（400,000 和 300,000 平方公里）和最大（43 和 19 平方公里）火山灰降落的年代初步确定分别为 54,000 和 220,000 年。这些灰层共同构成了所谓的“Worzel Ash”。这两层中最广泛的一层出现在所有三个火山灰区域，也可能与墨西哥湾大约 60,000 年的火山灰层相关。一些灰层与一系列底层反射体的相关性表明，在中美洲上层 100 m 沉积物中看到的整个反射体序列可归因于离散的火山灰层。
Trace and minor element analysis of 128 volcanic ash samples from 56 cores taken in the eastern equatorial and southeastern Pacific Ocean has allowed identification and correlation of individual volcanic ash layers over wide areas of the ocean floor. Three principal areas of ash deposition have been delineated, with probable source areas in Guatemala, El Salvador, Nicaragua, and Colombia or Ecuador. Analyses of continental pumice samples indicate vents near the Tecpan-Chimaltenango basin in the Guatemalan Highlands and the Lake Ilopango region of El Salvador. Many, perhaps all, of the ash layers do not date beyond 300,000 yrs. The two most extensive (400,000 and 300,000 km2) and voluminous (43 and 19 km3) ash falls have been tentatively dated at 54,000 and 220,000 yrs, respectively. Together these ash layers comprise the so-called “Worzel Ash.” The most extensive of the two layers occurs in all three ash areas and may also correlate with an ash horizon in the Gulf of Mexico dated at approximately 60,000 yrs. The correlation of some ash layers with a sequence of subbottom reflectors suggests that the entire sequence of reflectors seen in the upper 100 m of sediment off Central America can be attributed to discrete layers of volcanic ash.