Mafic Late Miocene–Quaternary volcanic rocks in the Kamchatka back arc region: implications for subduction geometry and slab history at the Pacific–Aleutian junction
Mafic Late Miocene–Quaternary volcanic rocks in the Kamchatka back arc region: implications for subduction geometry and slab history at the Pacific–Aleutian junction
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DOI：
10.1007/s00410-009-0447-9
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发表时间：
2010-05
影响因子：
3.5
通讯作者：
A. Volynets;T. Churikova;G. Wörner;B. Gordeychik;P. Layer
中科院分区：
文献类型：
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作者：
A. Volynets;T. Churikova;G. Wörner;B. Gordeychik;P. Layer
新的~（40）Ar/~（39）Ar和~（14）C年龄将堪察加弧后大量的基性火山活动限定在中新世（3-6 Ma）和晚更新世至全新世（<1 Ma）。微量元素和同位素组成表明，较老的岩石来自亏损地幔，通过俯冲流体熔融（>20%）。较年轻的岩石形成于弧后，熔融程度较低，涉及富集的地幔成分。弧前和堪察加盆地中部也被晚更新世的高原熔岩和盾状火山覆盖。因此，这些大规模喷发的焦点随着时间的推移而迁移，这可能是皇帝海山俯冲和板块在地形增生期间回滚期间变陡的环境中高流体通量的结果。全新世火山活动的北方终止点位于堪察加半岛之下俯冲太平洋板块的边缘，弧后地区没有观察到“板缘效应”。
New40Ar/39Ar and published14C ages constrain voluminous mafic volcanism of the Kamchatka back-arc to Miocene (3–6 Ma) and Late Pleistocene to Holocene (<1 Ma) times. Trace elements and isotopic compositions show that older rocks derived from a depleted mantle through subduction fluid-flux melting (>20%). Younger rocks form in a back arc by lower melting degrees involving enriched mantle components. The arc front and Central Kamchatka Depression are also underlain by plateau lavas and shield volcanoes of Late Pleistocene age. The focus of these voluminous eruptions thus migrated in time and may be the result of a high fluid flux in a setting where the Emperor seamount subducts and the slab steepens during rollback during terrain accretions. The northern termination of Holocene volcanism locates the edge of the subducting Pacific plate below Kamchatka, a “slab-edge-effect” is not observed in the back arc region.