Archean blocks and their boundaries in the North China Craton: lithological, geochemical, structural and P–T path constraints and tectonic evolution
Archean blocks and their boundaries in the North China Craton: lithological, geochemical, structural and P–T path constraints and tectonic evolution
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DOI：
10.1016/s0301-9268(00)00154-6
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发表时间：
2001-03
影响因子：
3.8
通讯作者：
Guochun Zhao;S. Wilde;Peter A. Cawood;M. Sun
中科院分区：
文献类型：
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作者：
Guochun Zhao;S. Wilde;Peter A. Cawood;M. Sun
对岩石学、地球化学、年代学、构造和变质P-T路径资料的研究表明，华北克拉通的基底可分为东西地块，由主要的地壳边界分隔，大致相当于一个300公里宽的跨华北造山带的边界。东部地块主要由晚太古宙的角状调质-长闪质-花岗闪长岩（TTG）岩基组成，岩基周围环绕着吻合的网络和从绿片岩到麻粒岩相变质的小火山岩和沉积岩的开放到紧密型的线性带，具有逆时针的P-T路径。东部地块局部存在早、中太古代岩石，但受2.5 Ga构造热事件的改造，其构造历史尚不清楚。西地块具有与东部地块相似的晚太古代组合、构造样式和变质历史，但其不同之处在于缺少早-中太古代组合，并被古元古代孔石覆盖和交错，受1 ~ 1.8 Ga顺时针P-T路径变质事件影响。结合TTG片麻岩的广泛暴露、基性岩与陆相拉斑玄武岩的亲缘关系、大量马马长岩的存在、主要的与底孔有关的锥形构造、逆时针的P-T路径以及TTG和超基性到基性岩的初始侵位到区域变质作用开始的较短时间跨度，提出了东、西地块晚太古代基底岩形成和演化的地幔柱模式。在这两个地块之间是由两大断裂系统所包围的跨华北造山带，由晚太古代至古元古代TTG片麻岩和花岗岩类组成，交错着丰富的沉积岩和火山岩，其地球化学解释是在岩浆弧和弧内盆地环境中发育的。这些岩石在晚古元古代（~ 1.8 Ga）经历了多期挤压变形和高峰高压变质作用，随后在东、西地块的碰撞作用下被快速挖掘，导致华北克拉通的合并。
An examination of lithological, geochemical, geochronological, structural and metamorphic P–T path data suggests that the basement of the North China Craton can be divided into Eastern and Western Blocks, separated by major crustal boundaries that roughly correspond with the limits of a 300 km wide zone, called the Trans-North China Orogen. The Eastern Block consists predominantly of Late Archean domiform tonalitic–trondhjemitic–granodioritic (TTG) batholiths surrounded by anastomosing networks and linear belts of open to tight synforms of minor volcanic and sedimentary rocks metamorphosed from greenschist to granulite facies at ∼2.5 Ga, with anticlockwise P–T paths. Some Early to Middle Archean rocks are locally present in the Eastern Block, but their tectonic history is unclear due to reworking by the 2.5 Ga tectonothermal event. The Western Block has a Late Archean assemblage, structural style and metamorphic history similar to that of the Eastern Block, but it differs in the absence of early to middle Archean assemblages and in being overlain by and interleaved with Paleoproterozoic khondalites, which were affected by a ∼1.8 Ga metamorphic event involving clockwise P–T paths. A mantle plume model is proposed for the formation and evolution of Late Archean basement rocks in the Eastern and Western Blocks based on a combination of extensive exposure of TTG gneisses, affinities of mafic rocks to continental tholeiitic basalts, presence of voluminous komatiitic rocks, dominant diaprism-related domiform structures, anticlockwise P–T paths, and a short time span from the primary emplacement of TTG and ultramafic to mafic rocks until the onset of regional metamorphism. Between the two blocks is the Trans-North China Orogen which is bounded by two major fault systems and is composed of Late Archean to Paleoproterozoic TTG gneisses and granitoids, interleaved with abundant sedimentary and volcanic rocks that are geochemically interpreted as having developed in magmatic arc and intra-arc basin environments. These rocks underwent multiple phases of compressional deformation and peak high-pressure metamorphism followed by rapid exhumation during the Late Paleoproterozoic at ∼1.8 Ga as a result of collision between the Eastern and Western Blocks, resulting in the amalgamation of the North China Craton.