Petrogenesis of the earliest Early Cretaceous mafic rocks from the Cona area of the eastern Tethyan Himalaya in south Tibet: Interaction between the incubating Kerguelen plume and the eastern Greater India lithosphere?
Petrogenesis of the earliest Early Cretaceous mafic rocks from the Cona area of the eastern Tethyan Himalaya in south Tibet: Interaction between the incubating Kerguelen plume and the eastern Greater India lithosphere?
复制标题
DOI：
10.1016/j.lithos.2007.06.024
复制
发表时间：
2008
期刊：
影响因子：
3.5
通讯作者：
Di‐Cheng Zhu;X. Mo;G. Pan;Zhidan Zhao;G. Dong;Yuruo Shi;Z. Liao;Li-quan Wang;Changyong Zhou-Changyong
中科院分区：
文献类型：
--
作者：
Di‐Cheng Zhu;X. Mo;G. Pan;Zhidan Zhao;G. Dong;Yuruo Shi;Z. Liao;Li-quan Wang;Changyong Zhou-Changyong
冈瓦纳大陆东部的分裂和凯尔盖朗地幔柱活动之间的关系是一个有争议的话题。藏南喜马拉雅山东段科纳地区广泛出露科纳基性岩石，本文对科纳基性岩石进行了研究，以评价这种关系。科纳基性岩主要由块状玄武岩流和闪长岩或岩脉组成，并分为三组。第1组由玄武岩流和闪长岩床或岩脉组成，以较高的TiO 2和P2 O 5含量和OIB样微量元素模式为特征，其Nd（T）值范围较大（+1.84 ~+4.67）。第1组闪长岩的年龄为144.7± 2.4Ma。第2组为辉长岩岩床或横切辉长岩侵入体，其特征为TiO 2和P2 O 5含量较低，微量元素模式为“亏损”型，具有相对较高的、均匀的Nd（T）值（+5.68 ~+6.37）。第2组辉长岩型闪长岩脉的年龄为131.1± 6.1Ma。第3组玄武质熔岩与晚侏罗世-早白垩世泥质沉积物互层;它们的成分介于第1组和第2组之间，微量元素模式从平坦到略微富集。Sr-Nd同位素数据和REE模拟表明，不同程度的部分熔融不同的地幔源成分（富集石榴石-单斜辉石橄榄岩组1和尖晶石-二辉橄榄岩组2，分别）可以解释的科纳镁铁质岩石的化学多样性。的科纳基性岩石和玄武岩之间的地球化学相似性可能创建的Kerguelen羽的时空约束的基础上，似乎表明，孵化Kerguelen羽模型是更合理的比一个模型的正常裂谷（nonplume）的科纳基性岩石的代。第1组被解释为与孵化的Kerguelen羽-岩石圈相互作用有关;第2组可能与无水岩石圈和上升的贫化软流圈之间的相互作用有关，软流圈被来自Kerguelen羽的“液滴”富集，而第3组可能归因于热侵蚀，导致岩石圈在浅地壳水平的岩浆房/岩浆池的长期孵化期间部分熔融。Cona基性岩石可能与冈瓦纳大陆东部岩石圈从150-145 Ma到130 Ma的逐渐减薄有关。我们的新观察似乎表明，Kerguelen羽可能早在最晚的侏罗纪或最早的白垩纪时期就已经开始孵化，孵化的Kerguelen羽可能在大印度，印度东部和澳大利亚西北部的分裂中发挥积极作用。
The relationship between the breakup of eastern Gondwanaland and the Kerguelen plume activity is a subject of debate. The Cona mafic rocks are widely exposed in the Cona area of the eastern Himalaya of south Tibet, and are studied in order to evaluate this relationship. Cona mafic rocks consist predominantly of massive basaltic flows and diabase sills or dikes, and are divided into three groups. Group 1 is composed of basaltic flows and diabase sills or dikes and is characterized by higher TiO2and P2O5content and OIB-like trace element patterns with a relatively large range of ɛNd(T) values (+1.84 to +4.67). A Group 1 diabase sill has been dated at 144.7±2.4 Ma. Group 2 consists of gabbroic sills or crosscutting gabbroic intrusions characterized by lower TiO2and P2O5content and “depleted” N-MORB-like trace element patterns with relatively higher, homogeneous ɛNd(T) values (+5.68 to +6.37). A Group 2 gabbroic diabase dike has been dated at 131.1±6.1 Ma. Group 3 basaltic lavas are interbedded with the Late Jurassic–Early Cretaceous pelitic sediments; they have compositions transitional between Groups 1 and 2 and flat to slightly enriched trace element patterns. Sr–Nd isotopic data and REE modeling indicate that variable degrees of partial melting of distinct mantle source compositions (enriched garnet–clinopyroxene peridotite for Group 1 and spinel-lherzolite for Group 2, respectively) could account for the chemical diversity of the Cona mafic rocks. Geochemical similarities between the Cona mafic rocks and the basalts probably created by the Kerguelen plume based on spatial–temporal constraints seem to indicate that an incubating Kerguelen plume model is more plausible than a model of normal rifting (nonplume) for the generation of the Cona mafic rocks. Group 1 is interpreted as being related to the incubating Kerguelen plume–lithosphere interaction; Group 2 is likely related to an interaction between anhydrous lithosphere and rising depleted asthenosphere enriched by a “droplet” originating from the Kerguelen plume, while Group 3 may be attributed to thermal erosion resulting in the partial melting of lithosphere during the long-term incubation of a magma chamber/pond at a shallow crustal level. The Cona mafic rocks are probably related to a progressively lithospheric thinning beneath eastern Gondwanaland from 150–145 Ma to 130 Ma. Our new observations seem to indicate that the Kerguelen plume may have started its incubation as early as the latest Jurassic or earliest Cretaceous period and that the incubating Kerguelen plume may play an active role in the breakup of Greater India, eastern India, and northwestern Australia.