华北克拉通东部太古宙壳幔作用与地壳生长方式

This proposal selects Archean Wutai-Western Hengshan-Yunzhong, Miyun-Chengde,Fuxin-Jinzhou, Anshan-Benxi, Jiaodong and Western Shandong metamorphic basement terranes that show typical plate-subduction or mantle-plume dynamic regimes with Eoarchean, Paleoarchean, Mesoarchean to Neoarchean geological signatures for investigations in lithological associations recording various crust/mantle interaction regimes at different evolutional stages. Combined with features of deformation and metamorphism and PTt trajectories, we are going to synthetically determine thermodynamic systems for every crust/mantle interaction regime. We systematically studies the lithological associations, petrology, mineralogy, whole-rock geochemistry and Sr-Nd-Pb isotopic systematics, zircon U-Pb-Lu-Hf-O isotopic systematics of the crust/mantle interactions in plate-subduction and mantle-plume and subduction-plume regimes, integrating εNd-t and εHf-t diagrams, and will determe time, petrogenesis of the every lithological associations, crustal growth and recycling features of every metamorphic terrane, and correctly distinguish geological signatures related by slab-subduction from those by mantle-plume and draw their identified indicators. The aims of this proposal want to establish an Archean time-space evolutionary model of plate-subduction, mantle-plume and subduction-plume joint crust/mantle interaction regimes and multiple crustal growth models. Whether or not existing Neoarchean superacontinent will be determined by features comparisons between East North China Craton and other Archean cratons in the world.

本项目选择华北克拉通东部太古宙五台-恒山西段-云中山、密云-承德、阜新-锦州、鞍山-本溪、胶东和鲁西地块等具有典型板片俯冲、地幔柱体制和从古太古代到中-新太古代地质体（记录）的典型地区，开展太古宙不同演化阶段不同壳幔动力学体制的岩石组合类型研究，通过各岩石组合、岩石学、矿物学、全岩和单矿物地球化学、全岩和单矿物Sr-Nd-Pb同位素体系、锆石和独居石U-Pb-Lu-Hf-O同位素体系、全岩εNd-t和锆石εHf-t图综合研究各岩石组合的时代和成因、地壳生长与再循环特征，结合变形变质作用和PTt轨迹特征，确定各岩石组合壳幔作用热动力学体制，提取板片俯冲、地幔柱和板片俯冲-地幔柱联合作用的岩石学、矿物学、地球化学和同位素特征指标，正确区分地幔柱和板片俯冲相关的地质记录，确定华北克拉通东部不同壳幔动力学体制和地壳生长方式及其时空演化，与世界各克拉通对比分析是否存在新太古代超大陆。

国家自然科学基金重点项目（41530207）重点研究了华北克拉通东部太古宙变质区火山岩和侵入岩岩石组合、岩石成因和变形特征，提出了地幔柱体制、板片俯冲体制和地幔柱-板片俯冲联合作用的地质学和地球化学识别标志，确定了中-新太古代以侧向增生为主的大陆地壳生长方式和壳幔热-动力学过程，获得了如下创新成果：（1）确定了从抚顺南部-苇子峪-大苏河北新太古代晚期蛇绿混杂岩带，发现了残留的大洋地壳蛇纹石化橄榄岩、异剥钙榴岩和配套的火山岩、侵入岩组合；（2）确定了本溪-歪头山~3.45Ga老地块于~2.9Ga与鞍山白家坟~3.8Ga老地块通过前俯冲对接方式形成辽东地区统一的古老陆核；（3）确定了冀东（含冀北）-辽西地区和辽东-辽北地区新太古代火山岩和TTG片麻岩、赞岐岩质钾质花岗岩的时空分带性，形成于从南向北后撤式俯冲-侧向增生的壳幔动力学机制；（4）通过壳源TTG片麻岩成因和一维热模拟方法相结合发展了热力学和微量元素模拟估算不同时期地壳厚度和热状态方法，重建了大陆岩石圈的热结构，结合新太古代晚期火山岩特征和成因研究，确定了新太古代晚期完全具备了板片俯冲物理条件；（5）全球范围的幔源火山岩类型、时空分布、成分演化和地幔氧逸度研究，发现3.8-3.2 Ga以科马提岩和MORB系列玄武岩为主，地幔氧逸度最低，指示地幔柱构造体制占据主导地位；3.2-2.7 Ga，全球出现大量钙碱性岩浆作用，地幔氧逸度突然升高，指示板片俯冲作用的全球性启动，逐渐取代地幔柱体制的主导地位；2.6-2.5 Ga绝大多数太古宙克拉通都进入了岩浆静默期，只有华北克拉通、印度Dharwar克拉通和南非Zimbabwe克拉通发育了地幔岩浆活动，地幔进一步被俯冲洋壳和沉积物熔体交代，越来越富集，氧逸度再度升高，指示板片俯冲机制成为全球主导机制。（6）发表本项目为第一标注论文30篇，第二标注的论文15篇， 共培养博士研究生8人。