Collaborative Research: The Flood Basalt-Alkalic Magmatism-Kimberlite Connection and the Temporal-Spatial Evolution of the Siberian Mantle Plume

9612113 Renne本项目将开展野外、岩石学、地球化学的多学科研究。北西伯利亚地台迈麦查-科图伊地区一套超基性-碱性和基性岩的同位素和年代学研究。该地区的火山-深部杂岩体在时间和空间上与二叠纪-三叠纪西伯利亚洪水玄武岩省（SFBP）密切相关。作为这项研究的一部分，P.I.s还将包括具有SFBP地幔柱的碱性和拉斑岩脉冲的金伯利岩。碱性岩石橄榄石中3He/3He测量的初步数据表明3He的来源为下地幔，并将碱性-迈麦查相与羽状相关的SFBP联系起来。需要更多稀有气体同位素比值（He, Ne， Ar和Xe）的测量来证实。提出了对2.8 km厚的麦麦查-科图伊火山剖面的金伯利岩、超基性-碱性和基性岩进行ar /39Ar定年，以确定火山作用的年龄和持续时间。在两年的资助期内，还将对这些岩石进行Nd， Sr， pb同位素和微量元素分析，包括用TCP-MS对稀土元素进行分析。分析结果将用于检查卡拉迈金伯利岩、迈麦查-科图伊剖面的超基性-碱性和基性火山岩的起源，以及大量的以拉斑岩为主的SFBP的起源，是否存在共同的岩石成因联系（例如地幔衍生的羽流）。即使这些数据不支持这种假设，所获得的数据仍将有助于制定和证实其他岩石成因模型。

9612113 Renne This project is to conduct a multi-disciplinary study of field, petrologic, geochemical. isotopic and geochronological study of a suite of ultrabasic-alkaline and mafic rocks of Maimecha-Kotui region of the northern Siberian platform. The volcano-plutonic complexes of this region are closely associated in time and space with the Siberian Flood Basalt Province (SFBP) of permo-Triassic age. As part of this study The P.I.s will also include the kimberlites with the alkalic and tholeiitic pulses of the SFBP mantle plume. Preliminary data on 3He/3He measurements in olivines of the alkalic rocks suggest a lower mantle source for the 3He and links the alkalic-Maimecha phase to the plume-related SFBP. More noble gas isotope ratio measurements (He, Ne, Ar and Xe) are needed for confirmation. 40Ar/39Ar age dating of kimberlites and of the ultrabasic-alkaline and mafic rocks of the 2.8 km thick Maimecha-Kotui volcanic section are proposed to determine age and duration of volcanism. Nd, Sr, Pb-isotopic and trace elemental analyses, including the rare earth elements by TCP-MS, will also be performed on these rocks during the two-year tenure of the grant period. The analytical results will be used to examine whether there is a common petrogenetic link (e.g., mantle-derived plume) for the origin of the Kharamai kimberlites, the ultrabasic-alkaline and mafic volcanic rocks of the Maimecha-Kotui section, and for the voluminous, predominantly tholeiitic SFBP. In the event that these data do not support such a hypothesis, the acquired date will still be useful in formulating and substantiating other petrogenetic models.