Depth of alkalic magma reservoirs below Kolekole cinder cone, southwest rift zone, East Maui, Hawaii
Depth of alkalic magma reservoirs below Kolekole cinder cone, southwest rift zone, East Maui, Hawaii
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DOI：
10.1016/j.jvolgeores.2005.01.001
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发表时间：
2005-07-15
影响因子：
2.9
通讯作者：
Fein, C
中科院分区：
文献类型：
--
作者：
Chatterjee, N;Bhattacharji, S;Fein, C
科莱科莱火山锥位于西南裂谷上，靠近东毛伊岛的顶峰地区，毗邻哈雷阿卡拉火山口。喷发的熔岩由硬粒质微玄武岩和碧玄岩组成。硬硅钙石中含有26 ~ 33%的橄榄石和单斜辉石斑晶。虽然单斜辉石斑晶的核心是不平衡的整体岩石成分，恢复矩阵组成通过图像分析表明，边缘的单斜辉石斑晶和斜长石微斑晶是在平衡与矩阵在许多样品。平衡压力计算单斜辉石边缘液体平衡，并从平衡组成的多相饱和液体，产量值在4.4和11.2 kb之间。此外，基于单斜辉石组合物的气压计表明，单斜辉石斑晶的核心结晶在约2.5 kb的压力高于轮辋。因此，Kolekole的碱性岩浆存在于延伸到壳幔边界以下的储层中。计算出的基质成分的低Mg含量表明，在下地壳和上地幔岩浆房中发生了广泛的高压分离结晶的母岩浆。(c)2005 Elsevier B. V.保留所有权利。
The Kolekole cinder cone is located on the southwest rift near the summit area of East Maui, adjacent to the Haleakala Crater. The erupted lavas consist of ankaramitic picro-basalts and basanites. The ankaramites contain 26 to 33 modal percent olivine and clinopyroxene phenocrysts. Athough the cores of the clinopyroxene phenocrysts are not in equilibrium with the bulk rock compositions, recovered matrix compositions through image analysis indicate that the rims of the clinopyroxene phenocrysts and plagioclase microphenocrysts are in equilibrium with the matrix in many samples. Equilibrium pressures calculated from clinopyroxene rim-liquid equilibrium, and from equilibrium compositions of multiple phase-saturated liquids, yield values between 4.4 and 11.2 kb. In addition, barometry based on clinopyroxene composition indicates that the cores of the clinopyroxene phenocrysts crystallized at approximately 2.5 kb higher pressures than the rims. Therefore, the alkalic magmas of Kolekole resided in reservoirs that extended well below the crust mantle boundary. The low Mg-content of the calculated matrix compositions indicates that extensive high pressure fractional crystallization of parental magmas occurred in the lower crust and upper mantle magma chambers. (c) 2005 Elsevier B.V. All rights reserved.