石香肠构造研究综述

石香肠构造是一种传统的线状构造，由于其在区域构造应力场方面的研究意义及其所包含的流变学信息和控矿意义等一直吸引着研究者的关注。简述了近几十年来石香肠构造在形态学研究上的进展，分析了其在理论研究上的成果，概括了其在应用研究方面的现状，并对当前及今后石香肠构造的研究方向提出了建议。     

Morphology and kinematics of boudinage vein systems,Great Keppel Island,Queensland

Strongly boudinaged sandstone beds in a Palaeozoic accretionary complex are exposed on Great Keppel Island, off the central Queensland coast. Viewed in profile, the boudins are folded around mesoscopic F₂ hinge zones and overprinted by S₂ foliation indicating formation either during Late Carboniferous subduction accretion (D₁) or during a previously unrecognised discrete early phase of the Permian deformation (D₂). Boudin profiles record an average stretch of 1.51, although the contribution of D₂ and later deformation is not determined. Viewed in the plane of bedding, vein traces are variable and oblique to boudin necks by an average of 12° anticlockwise. The overall en echelon arrangement of veins in boudin necks is a primary feature of the structure and cannot be attributed to later deformation. This pattern of veining indicates oblique extension of the boudin necks by low‐vorticity non‐coaxial flow within the plane of bedding. One possible setting with such kinematics is the limb of a non‐cylindrical fold.     

鄂东南铁山不对称鱼嘴状石香肠构造基质层中的应变分析

利用惯量椭圆法对鄂东南铁山不对称鱼嘴状石香肠构造基质层中不同位置的方解石进行二维有限应变测量。运动学涡度以及相关参数的等值线分布图表明:不对称鱼嘴状石香肠构造基质层中的应变分布是不均匀的。基质层中,靠近断开的能干层处的剪切变形中纯剪切占优势,伸长方向趋向于平行剪切方向;而靠近连续的能干层处的剪切变形中简单剪切占优势,伸长方向趋向于垂直剪切方向。     

Boudinage control on the emplacement of lodes of the Kalgoorlie goldfield

Literature on the Kalgoorlie goldfield is reviewed and boudinage is shown to be an important aspect of the structure of the field, the lode distribution to be coincident with the principal necks, and the configuration of the lodes to match the characteristic fracture patterns of classical boudin necks. Boudinage is therefore interpreted to be an important control on the emplacement of the mineralization. Boudinage and the concomitant introduction of mineralization is related to flattening of the Boomerang Anticline, which is consistent with the general consensus that mineralization is emplaced as hydrothermal veins during late‐stage deformation. This interpretation is proposed as a simpler alternative to other more complex shear‐related models and may be useful in exploration for deposits of similar type.     

Upper crust “boudinage” during post-collisional Miocene extension in Tuscany: Insights from the southern part of the Larderello geothermal area (Northern Apennines,Italy)

A geological study carried out in the southern part of the Larderello geothermal area (Northern Apennines) provides new information on the development mechanism and timing of the earlier extensional structures that formed during the Miocene post-collisional tectonics which affected the orogen. Staircase low-angle normal faults (LANFs) affected a multilayered thickened upper crust after the collisional stage, producing the lateral segmentation of the Tuscan Nappe, the deeper non-metamorphic tectonic unit of the Northern Apennines in the Tuscan area. The tectonic history recorded in two Tuscan Nappe discontinuous bodies revealed that the LANFs took place during the Middle–Late Miocene, displacing collisional structures developed from the Late Oligocene. These Tuscan Nappe bodies are delimited by detachment faults located at the base, within the Tuscan evaporites, and at the top within the Ligurian Units. Their western and eastern margins coincide with east-dipping ramps. These structures and the Tuscan Nappe bodies were later dissected by Pliocene–Quaternary high-angle normal faults. The reconstructed deformation history implies that the Tuscan Nappe bodies are extensional horses developed through an earlier asymmetrical east-dipping extensional duplex system, involved in block faulting during the later, Pliocene-Quaternary, stage of extension.     

构造流变计

根据构造形迹和应变式反演岩石流变性质的方法称为构造流变计,或简称流变计。目前提出的流变计主要有应变折射、能干层褶皱香肠构造、残斑翼尾样式。应变折射、能干层褶皱和香肠构造流变计已进入量化阶段。构造流变计 可用于研究不同尺度地质体的流变结构,也可用来研究地质体的流变学演化,具有很好的发展前景。     

基于透射电镜的香肠构造流变计研究

采用透射电镜(TEM)对采自奥地利东阿尔卑斯和北京西山的香肠构造中的香肠体和相应基质的样品进行了超微构造分析。结果表明细粒基质中的位错密度较粗颗粒香肠体中的位错密度明显低很多。故认为香肠体的变形机制以位错蠕变为主,而基质的变形机制则以扩散蠕变为主。这从一个侧面为香肠构造流变计的这一假设提供了超微观研究的依据。     

骨节状香肠构造形成机制研究——以湖北铁山为例

以湖北大冶铁山地区骨节状香肠构造为对象,根据其骨节缝形态、香肠层的剖面形态以及骨节缝填充脉体与香肠形成的期次关系,划分出13种骨节状香肠构造类型;通过对其物质组成的镜下鉴定,认为其形成过程中至少发生两期变形作用,并总结出三种力学机制①两期递进的垂直层面压缩变形叠加;②早期垂直层面压缩与后期平行层面剪切的叠加;③早期垂直层面压缩与后期平行层面挤压的叠加。     

鄂东南铁山不对称骨节状石香肠构造基质层中的应变测量与分析

鄂东南铁山是亚洲首个发现骨节状石香肠构造的地区。以该区不对称骨节状石香肠构造为研究对象,利用惯量椭圆法对其基质层进行有限应变测量,获得真应变差、运动学涡度等相关参数及有限应变椭圆长轴展布方位的分布图。对所获数据资料研究表明:该不对称骨节状石香肠构造基质层的应变受其能干层控制,有限应变值与其离能干层的距离趋于负相关,且与其矿物颗粒粒径呈负相关,在平行于石香肠构造伸展方向上基质层有限应变分布不均;石香肠体附近与之相近规模的变形构造可使其相应基质中的应变分布紊乱;该不对称骨节状石香肠构造是由早期平行于层面简单剪切叠加晚期平行层面伸长、垂直层面压缩的纯剪切作用形成。与不对称鱼嘴状石香肠构造对比研究表明,两者基质层中简单剪切与纯剪切的分布均分别与其相对增厚与减薄区段对应,而两者形态的不同主要与石香肠体不连续处充填物的能干性不同有关,再次表明两者均是较好的岩石流变学标志。