大巴山侏罗纪叠加褶皱与侏罗纪前陆

大巴山是NWW_SEE走向的中央造山带中惟一的向南凸出大型弧型褶皱带,与秦岭—大别造山带的构造特征明显不协调。研究表明,大巴山弧型构造卷入了侏罗纪地层,因此不属于三叠纪中央造山带。秦岭、大别山和大巴山最新的证据证实侏罗纪曾经发生陆内俯冲作用,大巴山是侏罗纪陆内造山作用的产物。大巴山西侧为典型的叠加褶皱变形样式,三叠纪近东西向褶皱叠加上近南北向褶皱构成横跨型干涉变形图像。由此,确立了侏罗纪复合前陆的存在,证明中国东部甚至亚洲东部侏罗纪陆内造山的广泛性,晚侏罗世的“燕山运动”是波及亚洲中东部的重要构造事件。     

赣北前震旦纪构造变形特征及其动力学意义

赣北存在近南北向(D1)、近东西向(D2)、北北西-北北东向(D3)三个世代的叠加褶皱.它们是华夏板块与扬子板块缓慢拼贴过程中应力向板内传递的结果,均形成于前震旦纪.从发生的时间来看,应与格林威尔造成山运动相当.     

东昆仑造山带前陆盆地的叠加褶皱及其变形机制

在东昆仑造山带的三叠纪洪水川群复理石岩系中,发育着两组斜歪－倒转褶皱：一组轴迹方向为北西向,与造山带主体构造线近一致;另一组为新发现的北东向,与造山带主体构造线近垂直,形成叠加褶皱．每一组褶皱均是压扁、纯剪切、纯剪切＋简单剪切三种变形机制的产物．北西向褶皱轴面的南西倒和北东向褶皱轴面的北西倒,与国内外典型的前陆盆地中的褶皱形态不尽相同,反映了动力基础是板块碰撞之后的近于垂直的北东及北西方向挤压应力相继作用下形成的叠加褶皱．北东向褶皱的发现,揭示了造山带中构造应力场的转换．     

东昆仑造山带前陆盆地的叠加褶皱及其变表机制

在东昆仑造山带的叠纪洪水群复理石岩系中,发育着两组斜歪－倒转褶皱一 轴 方向为北西向,与造山眩本构造经近一致;另一组为发现的北东向,与造山带主体构造经近垂直,形成叠加褶皱每一组褶皱均压扁、纯剪切、纯剪切＋简单剪切三种变形机制的产物,北西 褶皱轴面的南西倒和北东向褶皱轴面的北西倒,与国内外典型的前陆盆地中的褶皱形态不尽相同,反映了动力基础是板块碰撞之后的近于垂直的北东及北西方向抗日挤压应力相继作用下     

大巴山前陆北西向褶皱的厘定及其意义

大巴山位于南秦岭造山带与上扬子前陆交接部位,其西北缘地区发育规模大、方向各异、叠加特征明显的褶皱构造体系。通过关键地区的褶皱及其叠加变形的几何学、运动学及时空序列的研究鉴别出至少是三期褶皱构造,包括北东—近东西向、近南北—北北西向和北西向褶皱。本文详细介绍北西向褶皱的厘定依据和空间构造要素,研究其对晚侏罗世形成的大巴山弧形褶皱带的叠加改造及过程。根据区域变形的特征分析,以及下白垩统地层卷入北西向褶皱变形的事实,推测这组褶皱形成与早白垩世晚期或其后的收缩变形事件有关,但其地球动力学背景仍需进一步探讨。大巴山地区北西—南东向褶皱的厘定有助于完善和深化大巴山西缘地区构造演化及地壳变形历史的认识。     

赣东北侏罗纪陆盆的沉积建造及构造旋回

阐述下侏罗统林山组、中件罗统罗坳组、上侏罗统至下白垩统武夷群的建造类型及建造序列,总结了侏罗纪陆盆的发展阶段。本区中生代构造运动划分为３个亚旋回;印支亚旋回（分为Ⅰ幕金子运动,Ⅱ幕南象运动）、早期燕山亚旋回、晚期燕山亚旋回;４个构造幕,尤以燕山Ⅲ幕最为剧烈,使本区地抛由东升西降转变为西升东降。     

沉积岩区叠加褶皱及其成因机制

近来在岩石力学界及隧道工程中极为重视隧道的变形特性，即围岩挤出使隧道经受大范围变形的特征，与岩石发生瞬时变形的岩瀑现象相反，挤出现象是围岩逐渐缓慢地发生变形，此时随着隧道的开挖，沿室周边产生的应力已超过了围岩的强度。对围岩挤出的定义和围岩挤出力的预测及产生变形的特性在一些文献中虽然作过一些论述，但是难说是适当的和简明扼要的。     

纵弯褶皱叠加机制和类型的研究现状

叠加褶皱的研究是以叠加机制和叠加类型为基础的。从变质岩构造研究中形成的叠加褶皱理论是以剪切褶皱为基础,而沉积岩的纵弯褶皱叠加机制和类型均与之不同。国外有学者分别指出再褶皱时的斜纵弯褶皱机制和早期褶皱枢纽的迁移机制以及四种基本叠加类型。我国有人论述了早期褶皱的枢纽、拐线的迁移是正纵弯再褶皱的一种机制,依此提出了正纵弯叠加褶皱的三种基本类型。本文对这些成果的主要认识和依据予以介绍。     

对赣东北晚古生代放射虫的初步认识

基于以往大量的研究成果和基本地质事实,人们已认同江南造山带是一个新元古代的碰撞造山带,最近,一些研究者根据在赣东北新元古代蛇绿混杂岩带中发现的晚古生代含放射虫硅质岩,认为该蛇绿岩带中的硅质岩至少是晚古生代的产物,进而提出一个解体江南古陆、江南地区普存在晚古生代一中生代板溪洋的命题根据野外调查、室内化学分析等综合研究,本文认为赣东北含放射虫硅质岩是大陆边缘浅水相沉积产物,稀土元素特征不支持大洋地壳上的深水环境,强烈的印支期构造事件有可能使晚古生代含放射虫硅质岩发生构造运移,并与新元古代蛇绿岩彼此混杂。     

赣东北元古代蛇绿岩Sm—Nd同位素年龄及地质意义

江南古陆东南缘赣东北弋阳—德兴—婺源一线有一条蛇绿岩带,普遍认为它是二个一级大地构造单元的分界线,形成于元古代。推断蛇绿混杂岩是元古代古洋壳俯冲时被挤上来的碎片;也有人认为它是中生代二大古陆之间的缝合线。Sm-Nd矿物等时线给出1034±16Ma(MSWD=1.0)的同位素年龄,它符合元古代缝合带的观点,而不利于中生代缝合带。     

On the Age of the Ophiolitic Complexes in Northeastern Jiangxi:A Micropaleontological Analysis

The age assignment of cherts from ophiolitic/metamorphic complexes in northeastern Jiangxi is widely regarded as one of the crucial issues in the tectonic interpretation of South China. The ophiolitic and metamorphic complexes in northeastern Jiangxi have been traditionally regarded as part of the Proterozoic “Banxi (=Penhsi) Group” of the Jiangnan Uplift. However, recent reports of Late Paleozoic radiolarians from the rock complexes have caused some researchers to question the traditional interpretation of the tectonic and paleogeographic framework in the region; but other workers are suspicious about these findings. In order to test the validity of the putative radiolarians, we, an interdisciplinary study group including micropaleontologists, tectonic specialists and regional geologists, conducted field investigations and multiple re-samplings of the localities where the reported fossils were collected. Our comprehensive study shows that the chert of the ophiolitic complex and the associated low-grade metamorphic slate yield Mesoproterozoic and Neoproterozoic acritarchs, confirming the traditional view of their age assignment (Proterozoic); on the other hand, no recognizable radiolarian fossils have been discovered therein, thus raising questions about the recently published result of Paleozoic radiolarian findings. Probable causes for the putative radiolarian findings are thus discussed herein. Geochemical characteristics indicate that the chert sedimentation most probably occurred under a continental margin setting.     

赣东北侏罗纪陆盆的沉积建造及构造旋回

阐述下侏罗统林山组、中侏罗统罗坳组、上侏罗统至下白垩统武夷群的建造类型及建造序列 ,总结了侏罗纪陆盆的发展阶段。本区中生代构造运动划分为 3个亚旋回 :印支亚旋回 (分为Ⅰ幕金子运动 ,Ⅱ幕南象运动 )、早期燕山亚旋回、晚期燕山亚旋回 ;4个构造幕 ,尤以燕山Ⅲ幕最为剧烈 ,使本区地势由东升西降转变为西升东降。     

赣东北地区不同时代硅质岩的地球化学特征及其地质意义

赣东北地区硅质岩各时代均有不同程度的发育,各时代硅质岩的SiO2含量变化范围为74．90％～97．19％,Si／Al为10．84～93．21,与Al2O3呈较好的负相关关系,表明它们含有较高比例的陆源泥质沉积物,硅质岩样品的Al2O3／(Al2O3+F2O3)=0．60～0．99,Ce／Ce=0．99～1．22,(La／Ce)N=0．91～1．83,V／Y<5．78,Ti／V>17。上述特征表明本区硅质岩形成于大陆边缘构造环境,而与大洋盆地及洋中脊构造环境无关。自古生代以来,该地区没有出现深海大洋盆地环境。     

赣东北前寒武纪岩浆混合作用岩带的发现及其地质意义

在总结新近发现的赣北前寒武纪岩浆混合岩带地质特征的基础上,从地质学、岩相学和同位素地球化学的角度,论证了发生于这一特殊地质时期和地质背景下的岩浆混合作用。文中将该作用形成的岩浆混合杂岩体有效地分解为：（１） 偏酸性端员的岩浆岩（ 角闪石英正长岩、石英正长岩） ;（２） 基性端员岩浆岩（ 玄武玢岩、玄武安山玢岩） 和（３） 岩浆混合岩,后者又可分为非均一岩浆混合岩和均一岩浆混合岩（ 如石英二长闪长岩） 。阐明该岩浆混合作用是新元古期我国东南地区江南古洋向扬子古陆俯冲消减这一构造演化的重要物质表现;示踪该地区于中元古期（１４８ ～１８５ Ｇａ） 经历了一次与全球范围一致的壳 幔分离事件和新元古期（０８５ Ｇａ） 亏损地幔与大洋沉积物在源区混合的事件;确认该地区前寒武纪的岩浆混合作用和岩浆侵入作用实际上是一个连续的岩浆作用序列,并且两者受近南北向挤压的同一应力场条件所制约     

赣东北鹅湖岩体SHRIMP 锆石U-Pb 年龄、Sr-Nd-Hf 同位素地球化学与岩石成因

对赣东北鹅湖岩体进行了SHRIMP 锆石U-Pb 年代学、元素和Sr-Nd-Hf 同位素地球化学及岩石成因研究。SHRIMP 锆石U-Pb 定年结果表明,鹅湖岩体形成于早白垩世的（121.7±2.9） Ma;岩相学及元素和Sr-Nd-Hf 同位素特征表明鹅湖花岗岩属于S 型,主要是由地壳深处（至少40 km）的古元古代变质沉积岩发生部分熔融形成的,成岩过程中并没有发生强烈的分离结晶作用和幔源岩浆混合作用,赣东北地区早白垩世伸展构造背景造成的软流圈地幔上涌可能是下地壳岩石发生部分熔融的诱因。     

太行山中北段褶皱构造序列

太行山中北段中－深变质岩区的褶皱构造变形复杂，不同期次间叠加改造强烈，构造置换作用明显，作者采用变质岩区构造解析方法，在观察，测量，分析了大量构造面，线组构的基础上，划分出５期褶皱构造，建立了本区的构造变形序列，并认为构造变形经历了从强塑性变表到韧脆性变形的演化过程，反映出地壳从纵向增厚作用转变为变质核杂岩隆升的演化过程。     

Petrochemistry of Granitoids Along the Loei Fold Belt,Northeastern Thailand

Petrochemical characteristics of Permo‐Triassic granitoids from five regions (i) Mung Loei, (ii) Phu Thap Fah – Phu Thep, (iii) Phetchabun, (iv) Nakon Sawan – Lobburi, and (v) Rayong – Chantaburi along the Loei Fold Belt (LFB), northeastern Thailand were studied. The LFB is a north–south trending 800 km fold belt that hosts several gold and base‐metal deposits. The granitoids consist of monzogranite, granodiorite, monzodiorite, tonalite, quartz‐syenite, and quartz‐rich granitoids. These are composed of quartz, plagioclase, and K‐feldspar with mafic minerals such as hornblende and biotite. Accessory minerals, such as titanite, zircon, magnetite, ilmenite, apatite, garnet, rutile, and allanite are also present. Magnetic susceptibilities in the SI unit of granitoids vary from 6.5 × 10⁻³ to 15.2 × 10⁻³ in Muang Loei, from 0.1 × 10⁻³ to 29.4 × 10⁻³ in Phu Thap Fah – Phu Thep, from 2.7 × 10⁻³ to 34.6 × 10⁻³ in Petchabun, from 2.4 × 10⁻³ to 14.1 × 10⁻³ in Nakon Sawan – Lobburi, and from 0.03 × 10⁻³ to 2.8 × 10⁻³ in Rayong – Chantaburi. Concentration of major elements suggests that these intermediate to felsic plutonic rocks have calc‐alkaline affinities. Concentration of REE of the granitoids normalized to chondrite displays moderately elevated light REE (LREE) and relatively flat heavy (HREE) patterns, with distinct depletion of Eu. Rb versus Y/Nb and Nb/Y tectonic discrimination diagrams illustrate that the granitoids from Muang Loei, Phu Thap Fah – Phu Thep, Phetchabun, Nakon Sawan – Lobburi, and Rayong – Chantaburi formed in continental volcanic‐arc setting. New age data from radiometric K‐Ar dating on K‐feldspar from granodiorite in Loei and Nakhon Sawan areas yielded 171 ± 3 and 221 ± 5 Ma, respectively. K‐Ar dating on hornblende separated from diorite in Lobburi yielded 219 ± 8 Ma. These ages suggest that magmatism of Muang Loei occurred in the Middle Jurassic, and Nakon Sawan – Lobburi occurred in Late Triassic. Both Nb versus Y and Rb versus (Y + Nb) diagrams and age data indicate that Nakon Sawan – Lobburi granitoids intruded in Late Triassic at Nong Bua, Nakon Sawan province and Khao Wong Phra Jun, Lobburi province in volcanic arc setting. Muang Loei granitoids at the Loei province formed later in Middle Jurassic also in volcanic arc setting. The negative δ³⁴S_CDT values of ore minerals from the skarn deposit suggest that the I‐type magma has been influenced by light biogenic sulfur from local country rocks. The Au‐Cu‐Fe‐Sb deposits correlate with the magnetite‐series granitoids in Phetchabun, Nakon Sawan – Lobburi and Rayong – Chantaburi areas. Metallogeny of the Au and Cu‐Au skarn deposits and the epithermal Au deposit is related to adakitic rocks of magnetite‐series granitoids from Phetchabun and Nakon Sawan areas. All mineralizations along the LFB are generated in the volcanic arc related to the subduction of Paleo‐Tethys. The total Al (^TAl) content of biotite of granitoids increases in the following order: granitoids associated with Fe and Au deposit < with Cu deposit < barren granitoids. X_Mg of biotite in granitoids in Muang Loei indicates the crystallization of biotite in magnetite‐series granitoids under high oxygen fugacity conditions. On the other hand, low X_Mg (<0.4) of biotite in magnetite‐series granitoids in Phu Thap Fah – Phu Thep and Rayong – Chantaburi indicates a reduced environment and low oxygen fugacity, associated with Au skarn deposit (Phu Thap Fah) and Sb‐Au deposit (Bo Thong), respectively. The magnetite‐series granitoids at Phu Thap Fah having low magnetic susceptibilities and low X_Mg of biotite were formed by reduction of initially oxidizing magnetite‐series granitic magma by interaction with reducing sedimentary country rocks as suggested by negative δ³⁴S_CDT values.