花岗岩定位机制研究进展

近20年来，由于新理论、新方法和新技术的引入，使花岗岩定位机制的研究取得了很大进展，具体表现在复合定位机制的提出，定位机制控制因素的多样性，研究方法的更新等方面。在花岗质岩浆上升定位过程中，不仅肯定了浮力等作用的重要性，而且特别强调了构造通道、构造空间和构造应力作用方式的重要地位。花岗岩体构造研究的新进展，也为花岗地质岩浆的生成、运移、定位以及构造变形等一系列问题的解决提供了新的思路和有效的方法。     

花岗岩体定位机制研究进展综述

花岗岩体的定位机制及其派生的构造是当代花岗岩地质学研究的前沿。本文从花岗岩体定位机制研究的意义出发,综述了花岗岩体定位的几种主要机制的研究进展、花岗岩体定位机制的控制因素、以及花岗岩体定位机制的研究方法等。最后,提出了加强我国花岗岩体定位机制及花岗岩体构造研究的建议。     

花岗岩构造和定位机制研究进展

近２０年来，由于新理论、新方法和新技术的引人，使花岗岩构造和定位机制研究取得了很大进展，尤其是花岗岩定位过程中的流变学行为，岩浆上升的驱动机制，花岗岩的空间，花岗岩构造型式和定位机制等的研究，在一定程度上带有突破性。花岗质岩石定位过程中的流变性质不再被认为是类似于牛顿流体，运动遵循流体定律的液体，而是一个由岩浆作用（牛顿流体）到固态作用的连续力学介质，尤其强调了花岗质岩石定位过程中的假塑性体（宾厄姆体）性质。在花岗质岩浆上升定位过程的研究中，不仅肯定了浮力的重要作用，而且特别强调了构造通道、构造空间和构造应力作用方式的重要地位。气球状膨胀作用、岩墙扩展作用和构造泵吸作用是３种花岗岩体的重要定位机制，无一不与构造作用有关。花岗岩体构造型式的研究已成为研究花岗岩体定位机制的有效方法。     

小秦岭小河岩体岩石谱系单位划分及其定位机制

小河岩体是一个“I”型高位深成岩体。采用岩石谱系单位的划分原则,依结构演化序列将小河岩体划分为甘沟、后沟两个单元,归并为小河超单元。通过对岩体构造、包体、空间位态和区域构造特征等分析,提出小河岩体为顺基底拆离断层经基性岩墙拓宽通道—被动上侵顶蚀—类岩墙扩张式就位的复合定位机制。中条期伸展构造为岩浆生成、侵位提供了热动力及潜在空间。     

花岗岩类分类与定位机制研究动向和进展

近年来国内外花岗岩类研究工作已获得了新的进展。本文综合性地评述了花岗岩类主要岩石成因分类,构造环境分类与对比特点,着重叙述了花岗岩体定位机制研究方法及研究实例;对深化我国特别是华南花岗岩类岩石成因一构造分类及定位机制的研究提出了具体建议。     

花岗岩类分类与定位机制研究动向和进展

近年来国内外花岗岩类研究工作已取得了新的进展。本文综合性地评述了花岗岩类主要岩石成因分类、构造环境分类与对比特点;着重叙述了花岗岩体定位机制研究方法及研究实例;对深化我国特别是华南花岗岩类岩石成因—构造分类及定位机制的研究提出了具体建议。     

成功的深部矿体定位预测——以山东夏甸金矿为例

山东夏甸金矿位于胶东招平断裂带中段。该地区不同时代多种典型构造动力机制交互叠置 ,构造岩复杂多样 ,岩浆活动发育 ,矿产丰富。运用复合成矿系统思想对该地区进行矿体定位预测 ,取得了初步成效 ,复合成矿系统的思想是翟裕生 (1992 )根据大宝山、铜官山等成矿实例提出 ,并认为不同时代成矿系列间的叠加复合是造成多成因矿床的重要原因 ,在我国多构造旋回区 ,这种成矿系列复合现象有更多的表现 ,可以作为区域成矿分析和成矿预测的一个重要思路。将复合成矿系统定义为 :在一定的成矿区带中 ,在不同地质时期形成的成矿系列间存在着复合关系 ,…     

山东招远灵山沟金矿床金矿化空间定位机制

通过对灵山沟金矿矿床地质特征和控矿构造组合特征研究表明,灵山沟金矿控矿构造组合样式为"结环"状,是主、次级断裂组合控矿,即灵山—北截断裂与其次级断裂构成的结环控制了灵山沟金矿的产出;同时研究了该金矿工业矿体的空间定位机制,建立了灵山沟金矿不同深度上工业矿体分别受灵北断裂(F1)和其次级断裂(F5)断裂交汇部位控制,以及热液上升通道控制的空间定位机制,从而解释了同一矿区存在产状明显不同的两类矿体的原因,为矿区及外围开展矿体定位预测和进一步预测找矿提供有益信息。     

生产矿山隐伏矿体定位预测

生产矿山隐伏矿体定位预测是当前成矿学和矿产勘查学的科学前沿和研究重点。本文系统探讨了生产矿山隐伏矿体定位预测的性质、特点、预测理论和技术方法;提出生产矿山隐伏矿体定位预测是一项大风险、高难度、强探索的科学系统工程;成功进行矿体定位预测的基础是成矿预测理论,关键是找矿方法和技术的突破;进行多学科联合、不同预测理论相互渗透、不同预测方法技术相互结合、同时引入新的预测理论和方法,从四维空间预测隐伏矿体的空间位置、形态及矿化强度是矿山找矿的最佳途径。     

汶川Ms 8.0级地震余震重新定位及其空间分布特征研究

对南四川台网提供的2008年5月12日至2008年12月31日期间发生的地震观测报告资料进行了整理,并根据研究需要从中挑选出了2957次地震事件用于地震定位研究.然后,采用双差定位方法对汶川Ms 8.0级地震及挑选出的余震进行了重新定位,得到2678个地震的震源位置,重新定位后走时均方根残差由重新定位前的1.01s降到了0.20s,水平和垂直方向标准差分别为±0.85km和±1.3km.余震震中沿走向分布的总长度约为350km,震源深度优势分布为5～20km,平均震源深度为11.4km.文章结合地表考察破裂、震源机制解等研究结果,对余震空间分布进行了更为详细的分段和讨论,提出以下3点认识:1)余震震中沿主破裂带表现出明显的空间分段活动特征,根据余震空间分布特征和震源机制解可推测断层运动方式由一开始的逆冲为主,经过渡段最终转换为以右旋走滑为主;2)沿小鱼洞-棉篪-理县和青川-文县方向延伸的北西向余震带存在两个与龙门山构造带走向近似垂直的捩断层;3)龙门山构造带的北段(水观乡以北),存在一个斜跨北川-映秀断裂和青川-平武断裂的隐伏断层,并且该隐伏断层参与了北段余震的发震过程.     

花岗岩构造与侵位机制研究进展

近年来对造山带花岗岩构造与侵位机制的研究表明，花岗岩不但可以侵位在区域伸展的构造背景，也可以侵位在区域挤压（缩短）的构造背景。花岗岩侵位受断裂的控制并不是像以前认为的那样明显，而是受多种侵位机制的共同作用，而构造样式和变形组构则是侵位机制研究的基础。提出了一些新的研究思路和方法。此外，对大别山中生代花岗岩构造、侵位机制作了简要讨论。     

Chlorite meniscus cement – implications for diagenetic mineral growth after oil emplacement

The possible influence on diagenesis of oil migration into reservoir sandstones is important for understanding their development. Although many studies have addressed the question of continued growth of diagenetic minerals after oil emplacement, there is little clear evidence of the timing of mineral growth relative to oil emplacement, nor of the possible mechanisms of continued mineral growth. This study presents an example of continued cementation by pore‐lining chlorite during and after the migration of oil into a Palaeocene turbidite sandstone reservoir near the Faroe Islands. Chlorite developed in two different textures. One texture occurs on framework grain surfaces adjacent to open pore space in contact with oil. The other texture occurs close to framework grain contacts where contact with oil appears to have been prevented by residual pore‐water menisci. The meniscus crystals are larger than those from open pore, implying that diagenetic clay mineral growth has continued after oil emplacement.     

华北东部晚中生代区域伸展背景下同构造花岗岩体的起源与就位

花岗质岩浆的起源、迁移及就位是研究大陆岩石圈流变学特性的重要方面。然而,板内伸展背景下同构造花岗岩体的岩浆来源、就位机制和岩浆流动与区域应力场的关系等问题缺乏系统性的总结。晚中生代期间华北板块东部逐渐变为区域伸展体制,同时中浅部地壳形成一系列的韧性剪切带、变质核杂岩和拆离断层,这些伸展构造往往伴有同剪切变形的花岗岩体。因此,华北东部是系统研究板内伸展背景下同构造花岗岩体的最佳区域。本文选取多个典型的同构造花岗岩体,进行综合分析。通过归纳总结这些同构造岩体的岩石地球化学和年代学资料,发现多数同构造岩体具有多个岩浆源区,且较早就位的中性岩席(单元)往往来自壳幔混合岩浆或新生下地壳的部分熔融,而较晚的酸性岩席(单元)则主要来源于古老下地壳的部分熔融。这一特点反映了同伸展岩体岩浆源区由深至浅的演化规律,也揭示了区域伸展背景下源自地幔的流体和热量是触发地壳部分熔融的重要因素。通过分析岩浆就位过程中围岩和岩体中形成的定向及变形组构,发现华北东部同伸展岩体的就位模式可分为三大类:以扁平岩床或岩基形式就位于中部地壳的水平韧性剪切带内;岩浆以近直立运移的方式形成长轴平行拆离断层的岩基,就位于变质核杂岩核部或拆离断层下盘;岩浆就位于再活化的先存断裂,通过膨胀作用、挤压围岩获得就位空间并使围岩变形,形成类似底辟作用的就位方式。剪切应力和浮力是影响岩浆运移方向的重要力学参数。岩浆自源区上升的过程中浮力起着主要控制作用,就位于韧性剪切带时剪切应力起着控制作用,就位于浅部地壳的脆-韧性过渡带时浮力的作用再次凸显。     

云南个旧市卡房矿田新山花岗岩侵位机制与成矿关系初探

文章综合了前人对花岗岩侵位机制的研究,对花岗岩几种重要的侵位机制进行了详述.在此基础上结合野外工作和实践,从围岩蚀变、流体运移、断裂控制等几个方面对云南个旧新山花岗岩体的侵位机制类型进行了综合分析,认为新山花岗岩体侵位机制类型属于岩浆底拱作用,新山矿段内形成的矿床主要有接触带铜锡多金属矿床、层脉状铜锡矽卡岩硫化矿床、变...     

Incremental emplacement and syn-tectonic deformation of Late Triassic granites in the Qinling Orogen: Structural and geochronological constraints

Granitoids are important components of major orogenic belts, and provide important information about the regional geodynamic evolution. The emplacement mechanism of granite plutons and its relationship with regional tectonics has long been discussed, although it still remains debated. The Qinling Orogen within the Central China Orogen was marked by the emplacement of numerous Late Triassic granitic plutons. Although the petrology, geochemistry and geochronology of these intrusions have been addressed in various studies, their tectonic setting remains controversial, particularly since the structural aspects not been evaluated in detail. In this study, we attempt to reconstruct the emplacement process of the Late Triassic Dongjiangkou pluton in the South Qinling Belt. Field observations show extensive syn-plutonic deformations both in the pluton and its contact zones. Microstructural observations demonstrate that fabrics in the pluton were mainly acquired during submagmatic flow to high-T solid-state deformation. Zircon U–Pb ages reveal that the pluton is a composite intrusion which is composed of two juxtaposed small plutons with distinct ages (~210 Ma and ~200 Ma). Al-in-hornblende thermobarometer indicates that the pluton was formed at depths ranging from 4.7 km to 8.8 km, with an increasing depth trend from the inner unit to the outer unit. Distribution of the internal fabrics shows two concentric patterns which are concordant with pluton margins at the pluton scale and were probably induced by the regional sinistral transpression. Integrating these analyses, an incremental emplacement model is proposed for the syn-tectonic pluton. This model not only solves the ‘room problem’ but also accounts for the zoned petrological features of the pluton. Combined with previous studies, we suggest that the Late Triassic granite plutons in the Qinling Orogen were emplaced under a syn-collisional convergence setting, and that the granite magmatism was probably controlled by regional tectonics. Additionally, the incremental emplacement model may be a common mechanism for the Late Triassic granite plutons.     

花岗岩的变形构造和定位机制

通过测定花岗岩及其围岩的应变类型、组构特点和变形历史,可以推断花岗岩的定位机制。本文简单介绍了组构测量的方法和不同定位机制的判断标志,并以若干实例强调说明区域构造应力同岩桨的自然浮力和上升趋势相结合,能够产生各种不同的定位机制。     

岩浆侵位机制研究综述

岩浆侵位机制是研究地球动力作用的重要依据,综合国内外资料,对岩浆侵位机制提出了按侵位深度,岩浆迁移距离,岩浆结晶程度的分类方案及其联合侵位类型。分别对各类侵位机制 岩浆侵位过程,特点,研究现状进行了综述,并讨论了岩浆定位空间问题和影响岩浆定位的因素。     

Spinel inclusions in olivine and plagioclase crystals in a layered gabbro: a marker and a tracer for primary phenocrysts in a differentiating magma reservoir

The problem of whether cumulate rocks were formed by crystal settling or by in situ crystallization after magma emplacement is an important issue concerning the mechanisms of magmatic differentiation. However, it is hard to distinguish these two processes for plutonic rocks because the primary texture and chemical composition have generally been modified by postcumulus processes. To contribute this problem, we studied the distribution and compositions of Cr-spinel inclusions hosted in olivine and plagioclase in the Murotomisaki Gabbroic Intrusion (MGI), SW Japan. It is shown that the olivine-hosted inclusions are restricted to specific horizons where accumulation of olivine phenocrysts is thought to have occurred and that the compositional variations of the Cr-spinel are explained by a secondary compositional modification that probably took place after the magma emplacement. It is also shown that the Cr-spinel inclusions in a chilled margin have suffered the least compositional modification and nearly retains the primary composition. Those in the interior of the intrusion, on the contrary, have been significantly modified by re-equilibration with residual melt driven by cation diffusions through the host phases. Those in plagioclase have been less modified. It is shown that all the spinel inclusions had primarily the same and common composition at the time of magma emplacement. This implies that all the inclusion-bearing crystals, olivine and plagioclase, represent primary phenocrysts that had already existed in the emplaced magma. In this way, spinel inclusion in the MGI may be regarded to be a useful petrographic “marker” for identifying intratelluric phenocrysts and also as a “tracer” to trace the motion of the primary phenocrysts after the magma emplacement.     

Analysis of fully coupled thermomechanical behaviour around a rigid cylindrical heat source buried in clay

The problem of fully coupled consolidation and heat flow around a rigid cylindrical heat source buried in clay has been studied. The governing equations of the problem are summarized in the paper and a finite element time-marching scheme to obtain an approximate solution to the governing equations is described. The stress–strain behaviour of the skeleton of the saturated soil has been represented by both a linear elastic model and the modified Cam clay soil model. The results of a limited parametric study are presented with the aim of understanding the major mechanisms of soil behaviour close to buried canisters of hot radioactive waste. A range of soil properties has been included in the study, and the effects of soil disturbance during canister emplacement have also been considered.