Electron microprobe characterization of ash layers in sediments from the central Bransfield basin (Antarctic Peninsula): evidence for at least two volcanic sources
Electron microprobe characterization of ash layers in sediments from the central Bransfield basin (Antarctic Peninsula): evidence for at least two volcanic sources
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DOI：
10.1017/s0954102002000214
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发表时间：
2002-12-01
影响因子：
1.6
通讯作者：
Smellie, JL
中科院分区：
文献类型：
--
作者：
Fretzdorff, S;Smellie, JL
布兰斯菲尔德海峡是一个狭窄的活动裂谷，有三个海底盆地，将南设得兰群岛与北方南极半岛隔开。布兰斯菲尔德海峡的火山活动在0.75 Ma之前开始，并继续进行，最近在欺骗岛、布里奇曼岛和企鹅岛的陆上喷发，海底热液活动和许多年轻的玄武岩海山位于沿着裂谷轴。重力岩心是从布兰斯菲尔德盆地中部的五个地点收集的。硅藻土泥与陆源碎屑和不连续的灰层互层，厚度可达10 cm，是所有岩心中最常见的沉积物类型。灰层内玻璃碎片的主要元素组成，除了最上层，成分相似的火山碎屑单位保存在欺骗岛，一个年轻的（< 0.75马）活跃的成层火山。最上层的火山灰层在成分上不能与任何已知的来源相匹配。它的存在表明，除了欺骗岛之外，还有一个火山中心为布兰斯菲尔德盆地提供了火山灰。根据成分独特的火山灰层的浅地层位置，仅在海底以下几分米，其源火山可能在历史时期（<几百年）活跃。
Bransfield Strait, a narrow active rift with three submarine basins, separates the South Shetland Islands from northern Antarctic Peninsula. Volcanism in Bransfield Strait commenced prior to 0.75 Ma and continues, with recent subaerial eruptions at Deception, Bridgeman and Penguin islands, submarine hydrothermal activity and numerous young basaltic seamounts located along the rift axis. Gravity cores were collected from five locations within the central Bransfield basin. Diatomaceous mud interbedded with terrigenous detritus and discrete ash layers up to 10 cm thick are the commonest sediment types in all the cores. The major element compositions of glass shards within the ash layers are, apart from the uppermost layer, compositionally similar to pyroclastic units preserved on Deception Island, a young (< 0.75 Ma) active stratovolcano. The uppermost ash layer cannot be closely matched compositionally to any known source in the Antarctic-Scotia Sea-southem South America region. Its presence indicates that a volcanic centre other than Deception Island contributed ash to the Bransfield basin. Based on the shallow stratigraphical position of the compositionally distinctive ash layer, only a few decimetres beneath the seafloor, its source volcano was probably active in historical times (< few hundred years).