On the long-distance transport of Ferrar magmas
On the long-distance transport of Ferrar magmas
复制标题
论费拉尔岩浆的长距离输送
DOI：
10.1144/sp302.4
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发表时间：
2008
影响因子：
5.3
通讯作者：
P. Leat
中科院分区：
文献类型：
--
作者：
P. Leat
摘要对早侏罗世费拉尔大火成岩省（LIP）的分布和地球化学关系进行了研究，认为该省的岩浆源位于早侏罗世南极-非洲裂谷边缘，支持该省侵位的侧向流动模型。来自彭萨科拉山脉的公开数据和最新分析表明，费拉火山的主要岩浆类型——法齐奥火山化学类型（MFCT）出现在塞隆山脉、沙克尔顿山脉、威斯威努纳塔克山脉、彭萨科拉山脉（全南极洲）和南非，以及著名的维多利亚地、南极洲、澳大利亚东南部和新西兰的露头。化学成分显示出有些不同，但足够相似，可以认为它们代表着密切相关的岩浆。对离解释岩浆源距离的地球化学趋势分析表明，随着距离的增加，Mg#和MgO丰度呈下降趋势，这与横向流动模型相一致。圣甲虫峰化学类型（SPCT）在地球化学上是非常均匀的，它在塞隆山脉（Theron Mountains）和威斯威努纳塔克（which way Nunataks）以岩浆的形式出现，在维多利亚地（Victoria Land）以熔岩的形式出现。尽管如此，Mg#、MgO、Ti/Y和Ti/Zr均随离解释源距离的增加而下降，这与岩浆横向流动过程中分馏结晶的发生一致。心流发生在堤防或（更有可能的）技能中。没有发现喂食堤防蜂群。MFCT的流动距离至少为4100公里，SPCT为3700公里，是地球上解释过的最长的横向岩浆流动。
Abstract The distribution and geochemical relationships of the Early Jurassic Ferrar large igneous province (LIP) are examined and it is concluded that they support the lateral flow model for the emplacement of the province, with a source along the strongly magmatic Early Jurassic Antarctica–Africa rifted margin. Published data and new analyses from the Pensacola Range are used to show that the dominant magma type in the Ferrar, the Mount Fazio chemical type (MFCT), occurs in the Theron Mountains, Shackleton Range, Whichaway Nunataks, Pensacola Mountains (all Antarctica) and South Africa, as well as well-known outcrops in Victoria Land, Antarctica, SE Australia and New Zealand. Chemical compositions are shown to be somewhat varied, but similar enough for them to be considered as representing closely related magmas. Examination of geochemical trends with distance from the interpreted magma source indicates that Mg# and MgO abundances decline with distance travelled, and it is argued that this is consistent with the lateral flow model. The Scarab Peak chemical type (SPCT), which occurs as sills in the Theron Mountains and Whichaway Nunataks, and as lavas in Victoria Land, is geochemically very homogeneous. Despite this, Mg#, MgO, Ti/Y and Ti/Zr all fall with distance from the interpreted source, consistent with fractional crystallization occurring during the lateral flow of the magmas. Flow took place in dykes or (more likely) sills. No feeder dyke swarm has been identified. The distances flowed, at least 4100 km for MFCT and 3700 km for SPCT, are the longest interpreted lateral magma flows on Earth.