Temperature and melting of a ridge-centred plume with application to Iceland. Part I: Dynamics and crust production
Temperature and melting of a ridge-centred plume with application to Iceland. Part I: Dynamics and crust production
复制标题
以山脊为中心的羽流的温度和融化，适用于冰岛。
DOI：
10.1111/j.1365-246x.2004.02311.x
复制
发表时间：
2004
影响因子：
2.8
通讯作者：
A. Junge
中科院分区：
文献类型：
--
作者：
T. Ruedas;H. Schmeling;G. Marquart;A. Kreutzmann;A. Junge
摘要
在这项研究和一篇论文中，建立了具有不同温度异常的ΔTp和不同比例的滞留熔体ϕEX的羽流系统中对流和熔体产生的数值模型。超过保留阈值的熔体分别用于形成脊状结壳和羽状壳，其厚度对ΔTP和ϕEX的变化很敏感。计算的地壳厚度与大洋中脊和冰岛的观测结果相比较，证实了早先的发现，即上地幔冰岛热柱的ΔTp约为150K-200K，冰岛地壳是厚的。它还表明，部分熔融的地幔中保留的熔体比例至多为1%。在首选的模式中，羽流融化发生在大约25到110公里的深度，距离扩散中心最高可达∼250公里。文中利用数值模型得到的温度场和熔体分数场作为地震速度异常和大地电磁响应函数的输入。此外，模型还表明，通过增强熔融、活跃的上升流和熔融区的范围和几何形状的综合作用，羽流的高温导致地壳厚度与羽流超温呈超线性增长。
SUMMARY
In this study and a companion paper, numerical models of convection and melt generation in a ridge-centred plume system are developed for plumes with different temperature anomalies ΔTP and varying fractions of retained melt ϕex. The produced melt in excess of the retention threshold is used to generate ridge and plume crust respectively, whose thickness is found to be sensitive to changes in ΔTP and ϕex. Comparison of calculated crustal thicknesses with observations from mid-oceanic ridges and from Iceland confirms earlier findings that ΔTP of the Iceland plume in the upper mantle is about 150–200 K and that the Icelandic crust is thick. It also suggests that the retained melt fraction in partially molten mantle is at most 1 per cent. In the preferred model, plume melting occurs between ca. 25 and 110 km depth, at up to ∼250 km from the spreading centre. The temperature and melt fraction fields from the numerical models are used as input for the derivation of seismic velocity anomalies and magnetotelluric response functions in the companion paper. Furthermore, the models reveal that the high temperatures of plumes result in a superlinear increase of crustal thickness with plume excess temperature through the combined effects of enhanced melting, active upwelling and the extent and geometry of the melting zone.
影响因子：
3.9
作者：
MCKENZIE, D;BICKLE, MJ
通讯作者：
BICKLE, MJ