Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as pla...Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with theδ18O-based age, it is suggested that ash Layer A is cor-related to the youngest Toba tuff （YTT）, Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic erup-tion event.展开更多
A volcanic ash layer was observed in the 3 ice cores on the Nelson Ice Cap,Antarctica.A comparison of major elemental composition of glass shards from the 3 tephra layers with average whole-rock compositions of 1967-1...A volcanic ash layer was observed in the 3 ice cores on the Nelson Ice Cap,Antarctica.A comparison of major elemental composition of glass shards from the 3 tephra layers with average whole-rock compositions of 1967-1970 eruptions on the Deception Island and of glass shards from other suspected De- ception Island eruptions collected from Antarctic ice and firn indicate that the most reasonable source for the tephra in the Nelson Ice Cap cores is the 1970 eruption on the Deception Island.From the depth of the vol- canic ash layer and measured density profile of the cores,the net accumulation rate at the summit,Core GW,is 1200 g·cm^(-2)·a^(-1) during the past 20 years,and the net accumulation rates are 700 g·cm^(-2)·a^(-1) and 6 g·cm^(-2)·a^(-1) at sites N30 and N50,respectively.In the eastern part of the Nelson Ice Cap,the accu- mulation rate may be higher than that in the northern part,because no volcanic ash in ice cores was observed at similar depths collected from this region.展开更多
基金The National Natural Science Foundation of China under contract Nos 41106052 91228101 and 41306056the Fundamental Research Funds for National Nonprofit Institute Grant under contract No.JG0910
文摘Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with theδ18O-based age, it is suggested that ash Layer A is cor-related to the youngest Toba tuff （YTT）, Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic erup-tion event.
基金the National Natural Science Foundation of China the State Committee for Antarctic Research of China
文摘A volcanic ash layer was observed in the 3 ice cores on the Nelson Ice Cap,Antarctica.A comparison of major elemental composition of glass shards from the 3 tephra layers with average whole-rock compositions of 1967-1970 eruptions on the Deception Island and of glass shards from other suspected De- ception Island eruptions collected from Antarctic ice and firn indicate that the most reasonable source for the tephra in the Nelson Ice Cap cores is the 1970 eruption on the Deception Island.From the depth of the vol- canic ash layer and measured density profile of the cores,the net accumulation rate at the summit,Core GW,is 1200 g·cm^(-2)·a^(-1) during the past 20 years,and the net accumulation rates are 700 g·cm^(-2)·a^(-1) and 6 g·cm^(-2)·a^(-1) at sites N30 and N50,respectively.In the eastern part of the Nelson Ice Cap,the accu- mulation rate may be higher than that in the northern part,because no volcanic ash in ice cores was observed at similar depths collected from this region.
