滇西澜沧变质带变质作用和变形作用的关系

滇西澜沧变质带经历了两期变质变形事件，其时代分别为５１９Ｍａ和２８０～１９０Ｍａ。早期变质变形事件（Ｍ１Ｄ１）可由销长石和石榴石变斑晶的包裹体痕迹确定，形成近Ｅ－Ｗ向的变形构造格局。晚期变质变形作用（Ｍ２Ｄ２）以形成蓝片岩相矿物组合，如以蓝门石（青铝门石）＋多硅白云母＋绿泥石＋石英等为特征，并形成近Ｎ－Ｓ向的变形构造格局．钠质问石以青铝闪石和蓝闪石为主，白云母多为３Ｔ＋２Ｍ；型多硅白云母，其ｂｏ均值在９．０４０Ａ以上；蓝片岩相变质作用的Ｐ、Ｔ条件估计分别为０．６～０．７ＧＰａ和３００℃。晚期变质变形事件经历了二个主要阶段（Ｍ２ａＤ２ａ和Ｍ２ｂＤ２ｂ），分别伴随透入性面理（Ｓ２）和褶劈理（Ｓ３）的形成，蓝门石的４０Ａｒ－３９Ａｒ定年分别为２７９Ｍａ和２１４Ｍａ；Ｍ２ｃＤ２ｃ期局部受到热的扰动，以及出现大量的膝折带或宽缓褶皱。上述变质变形演化历史代表了澜沧变质带的隆升及剥蚀过程。     

韧性剪切带糜棱岩类质量平衡分析：以豫西秦岭群…

蛇尾剪带中糜棱岩的质量平衡分析表明：（１）以Ａｌ２Ｏ３守恒为限制条件，该剪切带损失了１０％±的质量和体积，糜棱岩类有Ｎａ２Ｏ，Ｚｒ，Ｓｒ获得；ＳｉＯ２，ＴｉＯ２，Ｆｅ２Ｏ３，ＭｇＯ，ＭｎＯ，ＣａＯ，ｋ２Ｏ及Ｃｏ，ＮｉＶ，Ｃｒ，Ｃｕ，Ｙ则损失了；（２）从初糜棱岩－糜棱岩，初糜棱岩－超糜棱岩和糜棱岩－超糜棱岩得出的质量等比线显示，同初糜棱岩相比，糜棱岩，超糜棱岩有ＣａＯ的获得，ＦｅＯ，ＭｇＯ，ＴｉＯ２     

辽南韧性剪切带糜棱岩类质量平衡分析

辽南韧性剪切带糜棱岩类质量平衡分析表明,该剪切带是在一个开放体系非等化学背景下形成的。该带中物质组分的迁移活动,主要发生在初糜棱岩－糜棱岩阶段。并以ＳｉＯ２的大量迁出,ＴｉＯ２,ＦｅＯ,ＭｎＯ,ＣａＯ,ＭｇＯ,Ｐ２Ｏ５的显著迁入为特 征。以Ａ１２Ｏ３为守恒条件,整个剪切带从原岩到糜棱岩的质量和体积发生了６．７４％～７．４８％损失。     

山东沂水峨山口韧性剪切带糜棱岩类质量平衡分析

峨山口韧性剪切带糜棱岩质量分析结果表明,该剪切带是在一个开放体系非等化学背景下形成的。该带中物质组分的迁移活动,主要发生在白云母石英片岩的形成阶段,并以Ｌｏｓ（流体）、ＳｉＯ２、ＦｅＯ、Ｆｅ２Ｏ３、ＴｉＯ２、Ｋ２Ｏ大量带入,而Ｎａ２Ｏ显著带出为特征。以Ａｌ２Ｏ３守恒为限制条件,整个剪切带从原岩到白云母石英片岩的质量和体积增大约５０％。     

泥河湾地区晚新生代生物地层带

本文根据岩石地层，哺乳动物化石及古地磁资料的综合分析研究，将泥河湾地区晚新生代生物地层划分为５个生物地层时限带，并推算出每个带的年限，它们是：（１）Ｈｉｐｐａｒｉｏｎ ｈｏｕｆｅｎｅｎｓｅ时限带，？－３．３０Ｍａ；（２）Ｍｉｍｏｍｙｓ ｏｒｉｅｎｔａｌｉｓ时限带，３．３０－２．４８Ｍａ；（３）Ｍｉｍｏｍｙｓ ｙｏｕｈｅｎｉｃｕｓ时限带，２．４８－１．８７Ｍａ；（４）Ａｌｌｏｐｈａｉｎｏｙｓ ｃｆ．     

滇西南澜沧群多硅白云母的多型和化学成分特征及其意义

从理论、实验及实际观察的结果都表明，随着压力的增加白云母中绿鳞石的含量显著地增加，可以认为在多期变质作用过程中，尤其是在变质压力不同的多期变质作用下，形成的多硅白云母，其化学成分就会打上不同的烙印。７７个多硅白云母化学成分的统计结果表明，澜沧群低级变质岩中的多硅白云母有两种成因。在Ｎａ－Ｍｇ相关图上，反映了高压和中压变质特征，高压变质的多硅白云母约占７０％。这与用多硅白云母ｂ０值鉴别的高压和中压变质是相吻合的。多硅白云母的多型为３Ｔ和２Ｍ１型，以２Ｍ１型为主     

Synchysite－（Y）（新奇钙钇矿）的晶体结构

新奇钙钇矿［ｓｙｎｃｈｙｓｉｔｅ－（Ｙ）］，ＹＣａ（ＣＯ＿ｓ）Ｆ，经单晶Ｘ射线魏森堡法研究表明属单斜晶系，空间群为Ｃ２／ｃ，由四圆衍射仪精化求得的晶胞参数为：ａ＝１２．０３９（３），ｂ＝６．９５０（１），ｃ＝１８．４３６（６），β＝１０２．４５（２）°。在四圆衍射仪上采用ＭｏＫα辐射收集的三维衍射数据，已经劳伦兹偏振因子校正，未做吸收校正。总共１０１９个衍射点的强度数据，应用全矩阵最小二乘法对结构进行了精化，经各向异性温度因子校正后，Ｒ因子为０．０８６。新奇钙钇矿具有（００１）层状结构特征，Ｃａ层和（ＹＦ）层由碳酸根层隔开。层的堆垛方式与Ｃ２／ｃ白云母类似，其中Ｃａ层与白云母中的Ｋ层相对应，ＣＯ＿３层和（ＹＦ）层则分别对应于白云母中的四面体层和八面体层。由于Ｃａ层上下两边的ＣＯ＿ｓ层的相对错动，形成了类似于２Ｍ＿２白云母的堆垛多型结构。     

鞍山地区太古宙地壳的构造演化序列

鞍山地区的太古宙变质岩，主要由花岗质岩石（约占９０％）和表壳岩（含铁岩系）组成。其中花岗岩包括铁架山花岗岩和弓长岭花岗岩，表壳岩由磁铁石英岩和绢云绿泥石石英片岩组成。表壳岩沉积年龄大于３０００Ｍａ，铁架山花岗岩侵位于２９００Ｍａ，稍后即发生第一幕韧性变形，在铁架山花岗岩中发育了ＮＥ走向片麻理，在表壳岩中形成同斜褶皱及轴面片理Ｓ＿１。２６００Ｍａ左右弓长岭花岗岩侵位，稍后又发生第二幕韧性变形，产生了ＮＮＷ逆向剪切带和ＮＥＥ走滑剪切带，这时含铁岩系中形成平行韧性剪切带的片理Ｓ＿２。２０００Ｍａ发生第三幕韧性变形，其中ＮＥＥ和ＮＮＷ向剪切性质与第二幕恰好相反。以上三幕韧性剪切序次，相对应的形成了片麻岩、糜棱岩和构造片岩。     

郯庐断裂中段鲁中基底韧性变形带的形成时代

郯庐断裂中段鲁中基底的韧性变形带可分为两类：（１）北东向韧性变形带,以发育中深层次的构造片麻岩为特征,形成于早中元古代花岗质岩体（２４８８Ｍａ）侵位之前;（２）北北东向韧性变形带,以中浅层次糜棱岩为特征,形成于晋宁期（９４１Ｍａ）。文中对以上两类韧性变形带的形成机制和时代进行了初步讨论。     

郯庐断裂中段鲁中基底韧性变形带的形成时代

郯庐断裂中段鲁中基底的韧性变形带可分为两类;（１）北东向韧性变形带,以发育中深层次的构造片麻岩为特征,形成于早中元古代花岗质岩体（２４８８Ｍａ）侵位之前;（２）北北东向韧性变形带,以中浅层次糜棱岩为特征,形成了晋宁期（９４１）Ｍａ。文中对以上两类韧性变形带的形成机制和时代进行了初步讨论。     

松辽盆地西缘断裂带中花岗质糜棱岩的锆石SHRIMP和云母氩-氩年龄及其构造意义

松辽盆地西缘发育大型的北北东走向韧性断裂带,该韧性断裂带的性质、活动时限一直存在争议,制约了对松辽盆地构造成因的认识以及松辽盆地西缘油气勘探开发的进展。腾克、金星及嘎拉山地区是松辽盆地西缘韧性断裂带的代表性出露区,主体岩石组合为条带状花岗质糜棱岩、眼球状花岗质糜棱岩等。腾克、金星及嘎拉山地区发育一组糜棱面理和线理,其中面理为110°~135°∠45°~65°、线理为倾伏向10°~25°,倾伏角10°~35°;其运动性质均显示左行走滑特征。确定韧性断裂带活动时限的样品采自构造带内花岗质糜棱岩的锆石和同变形云母,其中锆石SHRIMP谐和年龄为296.9~299.4 Ma;黑云母⁴⁰Ar-³⁹Ar年龄为(123.0±0.7)Ma,白云母的⁴⁰Ar-³⁹Ar年龄为(124.4±0.9)Ma。松辽盆地西缘韧性断裂带应该属于嫩江断裂带的北段。年龄结果表明该韧性断裂带中花岗岩侵位于晚石炭世,大型北北东向韧性构造变形发生于早白垩世。腾克金星嘎拉山剪切带控制松辽盆地西缘,同时表明松辽盆地在早白垩世经历了走滑挤压盆地演化阶段,这种大型北北东向韧性断裂带的形成可能与当时西太平洋伊泽纳崎板块向欧亚大陆俯冲发生转向有关。     

大别山东缘郯庐两期走滑剪切带形成的温压条件与造山带折返的关系

郯庐断裂带与大别造山带在大别山东缘相复合 ,并将大别—苏鲁造山带左行错开达 5 0 0km。本文以大别山东缘为研究背景 ,通过对郯庐断裂带两期左旋走滑韧性剪切带温压条件的估算及热年代学信息的分析 ,来探讨大别造山带在早侏罗—早白垩世之间的折返历史与隆升量。通过矿物组合、矿物变形特征以及白云母—绿泥石地质温度计得到郯庐早、晚两期剪切带的形成温度均为 4 0 0～ 4 5 0℃。通过多硅白云母Si原子数地质压力计计算得到早、晚两期剪切带的形成压力分别为 0 .2 5～ 0 .36GPa和 0 .2 4～ 0 .39GPa。考虑到剪切摩擦加热和构造超压的影响 ,笔者推断郯庐两期走滑剪切带形成的最大深度均不超过 12km ,且两期走滑剪切带的形成深度至多相差 1～2km。郯庐断裂带在约 190Ma和 12 8Ma经历了两期走滑冷却事件 ,而在此期间 ,大别造山带东缘经历了一个构造平静期 ,基本没有发生隆升。根据郯庐断裂带的信息 ,造山带在早白垩世的热隆事件中的隆升幅度小于 12km。     

Ar-Ar age of mylonites along the Merens Fault, central Pyrenees

Seven mylonitic samples and two coarse muscovites from the central Pyrenees have been dated by the ⁴⁰Ar-³⁹Ar method. Whole rock specimens of mylonite were cut out of thin-section chips allowing complete characterisation of mineralogy and texture. Several specimens showed rising staircase patterns in the range 50–90 Ma, with much higher ages in the highest temperature steps. This is believed to reflect mixing of argon released from micas with excess argon contained in plagioclase and released mainly at high temperatures. One biotite-quartz mylonite gave a plateau age of 93 ± 2 Ma. Other inferred mica ages are about 60–73 Ma for biotite and 50–60 Ma for muscovite; it is probable that biotite contains excess argon and that 50 Ma approximates to the cooling age in the mylonites. One coarse muscovite collected immediately below the major Mérens shear zone gave a Hercynian plateau age, while another collected within the Mérens zone gave a partially reset Hercynian age.Taken together, the data indicate that the shear zones were active in Alpine times < 100 Ma and probably about 50 Ma ago. They are believed to have formed during the early stages of Eocene compression in the Pyrenees. Deformation and resultant uplift probably terminated an important thermal event in this part of the Pyrenean basement, which may have begun at the time of the mid-Cretaceous North Pyrenean metamorphism (90–100 Ma).     

滇西高黎贡剪切带内花岗质糜棱岩LA-ICP-MS锆石U-Pb年龄及其构造意义

高黎贡变质带位于高黎贡走滑剪切带以西,呈SN向或NE-SW向带状展布,是滇西最显著的带状变质带之一,被认为是前寒武纪变质基底。选取高黎贡剪切带内的花岗质糜棱岩进行LA-ICP-MS锆石U-Pb定年,分别获得了41.9Ma±1.0Ma的岩浆结晶年龄和38.4Ma±2.1Ma的变质年龄。结合区域地质背景、地质演化、岩石组构和年代学资料,认为花岗质糜棱岩原岩结晶年龄为42Ma,遭受糜棱岩化的变质时间为38Ma,同时表明高黎贡剪切带右行走滑的起始时间为38Ma以前。     

新疆东天山红山金矿成矿时代研究

红山金矿区位于秋格明塔什—黄山韧性剪切带东段北缘,矿床成因研究表明,红山金矿的形成严格受该韧性剪切带控制,属于与韧性剪切带有关的糜棱岩型、超糜棱岩型矿床。花岗质糜棱岩中角闪石276.3Ma的Ar-Ar坪年龄给出了红山金矿床成矿事件的时代上限。金矿石样品中绢云母246.9Ma和246.5Ma的Ar-Ar坪年龄记录了金矿床主成矿期的时代。糜棱岩中新生白云母246.5Ma的Ar-Ar坪年龄,在误差范围内和金矿石样品中绢云母的Ar-Ar坪年龄完全一致,不仅为红山金矿床的剪切带型成因提供了进一步的佐证,也对金成矿时代给予了进一步的限定。     

闽—粤东南沿海大陆边缘韧性剪切带的基本特征

东南沿海大陆边缘剪切带是西太平洋活动大陆边缘构造带的组成部分,它是一条具有多次活动的左旋韧性平移剪切带。在本剪切带中可以观察到3种类型的构造:（1）规模巨大的呈北北东—北东向展布的糜棱岩带以及山拉伸线理组成的线状构造带。它们在平面上有明显的从断目两侧向中心递进变形特征;（2）呈北东走向陡倾角的糜棱叶理（Sa）、应变滑劈理或破劈理（Sb）、小型剪切带（Sc）;（3）由西到东断层作用样式和断层岩具有明显的递进变化特点。西部（浅部）断层作用以脆性剪切滑动为主,其断层岩则由假玄武玻璃及镜面糜棱岩组成;中部断层作用以跪—韧性剪切为主,为断层泥—碎裂岩—超碎裂岩;东部(深部,以韧性剪切作用为主,其断层岩为暖棱岩—花岗糜桂片麻岩—眼球状糜棱岩系列。以上特点表明在本剪切带内透入性和非透入性变形之间有着密切的关系,反映出在变形过程中具有由韧性变形逐渐向脆性变形的发展趋势。     

鄂西北竹山银洞沟银金矿床构造控矿特征

银洞沟银金矿床位于扬子地台北缘武当推覆体西部,产于武当群变火山岩组与变沉积岩组间的顺层型韧性剪切带中,与构造变形密切相关。晋宁期的伸展作用产生了顺层型韧性剪切带,韧性变形变质作用促使原岩中银金等贵金属、多金属元素活化迁移,随剪切变形变质热液在强应变带中沉淀,形成初始矿源层。印支期的陆陆碰撞作用,促成不同层次面型剪切带岩石褶皱、韧脆性推覆,成矿元素从初始矿源层中再次活化、运移,随着沿褶皱轴面劈理发育的烟灰色糜棱岩化石英脉的形成,沉淀富集于石英脉中,形成银金矿床。脆性变形的叠加,使含矿石英脉产生扭动,促使成矿元素的局部富集,形成透镜状或板状矿体。成矿元素的垂直分带是由构造环境的变化导致成矿元素的叠生作用而形成的。多硅白云母及白云母年龄的测定表明该矿床的成矿期为印支期。     

钦-杭成矿带南段庞西垌断裂带热年代学证据

庞西垌断裂带是钦-杭成矿带南段众多NE向韧性剪切带的其中一条,控制着一系列韧性剪切带型银金矿床的分布.对其进行热年代学研究有助于了解钦-杭成矿带南段NE向韧性剪切带的构造演化及其对伴生矿床的控制作用.获得的庞西垌断裂带内糜棱岩中两件白云母40Ar/39Ar总气体年龄分别为221.98±1.16 Ma和223.77±1.16 Ma.据此认为庞西垌断裂带在印支期发生韧性剪切活动,为伴生矿床的形成提供了有利空间;在同一糜棱岩样品中获得的磷灰石、锆石裂变径迹年龄分别为64.83±4.13 Ma和75.69±2.88 Ma,结合热史模拟结果可以得出,庞西垌断裂带在75~60 Ma期间发生了快速冷却作用（6.2 ℃/Ma）,与区域整体缓慢冷却过程（1.5 ℃/Ma）差别显著,据此推测庞西垌断裂带可能在约75~60 Ma期间再次发生活动,而庞西垌银金矿床可能形成于晚白垩世.      

Mineralogy and geochemistry of Nb-, Ta-, Sn-, U-, Th-, and Zr-bearing granitic rocks from Abu Rusheid shear zones,South Eastern Desert,Egypt

Granite-hosted,Nb-,Ta-,Sn-,U-,Th-,and Zr(Hf)-bearing mineralization from the Abu Rusheid shear zones occurs about 97 km southwest of the town of Marsa Alam,South Eastern Desert,Egypt.The SSE-trending brittle-ductile Abu Rusheid shear zones crosscut the peralkalic granitic gneisses and cataclastic to mylonitic rocks(mylonite,protomlyonite,and ultramylonite).The northern shear zone varies in width from 1 to 3 m with a strike length of >500 m,and the southern shear zone is 0.5 to 8 m wide and >1 km long.These shear zones locally host less altered lamprophyre and locally sheared granitic aplite-pegmatite dykes.The rare-metal minerals,identified from the peralkalic granitic gneisses and cataclastic to mylonitic rocks are associated with muscovite,chlorite,quartz,fluorite,pyrite,magnetite,and rare biotite that are restricted to the Abu Rusheid shear zones;these are columbite-tantalite and pyrochlore(var.betafite) in the northern shear zone and ferrocolumbite in the southern shear zone.Cassiterite occurs as inclusions in the columbite-tantalite minerals.U-and Th-minerals(uraninite,thorite,uranothorite,ishikawaite,and cheralite) and Hf-rich zircon coexist.Magmatic(?) zircon contains numerous inclusions of rutile,fluorite,U-Th and REE minerals,such as uranothorite,cheralite,monazite,and xenotime.Compositional variations in Ta/(Ta+Nb) and Mn/(Mn+Fe) in columbite range from 0.07-0.42 and 0.04-0.33,respectively,and Hf contents in zircon from 1.92-6.46 of the two mineralized shear zones reflect the extreme degree of magmatic fractionation.Four samples of peralkalic granitic gneisses and cataclastic to mylonitic rocks from the southern shear zone have very low TiO2(0.02 wt%-0.04 wt%),Sr [(15-20)×10-6],and Ba [(47-78)×10-6],with high Fe2O3T(0.94 wt%-1.99 wt%),CaO(0.14 wt%-1.16 wt%),alkalis(9.2 wt%-10.1 wt%),Rb [(369-805)×10-6],Zr [(1033-2261)×10-6],Nb [(371-913)×10-6],U [(51-108)×10-6],Th [(36-110)×10-6],Ta [(38-108)×10-6],Pb [(39-364)×10-6],Zn [(21-424)×10-6],Y [(8-304)×10-6],Hf [(29-157)×10-6],and ∑REE [(64-304)×10-6],especially HREE [(46-167)×10-6].Three samples from the northern shear zone also have very low TiO2(0.03 wt%),Sr [(11-16)×10-6],and Ba [(38-47)×10-6],with high Fe2O3T(1.97 wt%-2.91 wt%),CaO(0.49 wt%-1.01 wt%),alkalis(7.2 wt%-8.3 wt%),Rb [(932-978)×10-6],Zr [(1707-1953)×10-6],Nb [(853-981)×10-6],Ta [(100-112)×10-6],U [(120-752)×10-6],Th [(121-164)×10-6],Pb [(260-2198)×10-6],Zn [(483-1140)×10-6],Y [(8-304)×10-6],Hf [(67-106)×10-6],and ∑REE [(110-231)×10-6],especially HREE [(91-177)×10-6].The very high Rb/Sr(57.5-88.9),and low Zr/Hf(16.9-25.6),Nb/Ta(7.7-9.8),and Th/U(0.21-1.01) are consistent with very frac-tionated fluorine-bearing granitic rocks that were altered and sheared.The field evidence,textural relations,and compositions of the ore minerals suggest that the main mineralizing event was magmatic(629+/-5 Ma,CHIME monazite),with later hydrothermal alteration and local remobilization of the high-field-strength elements.     

Very high strains recorded in mylonites along the Alpine Fault, New Zealand: implications for the deep structure of plate boundary faults

Oblique displacement on the Alpine Fault, which forms the principal structure along the Australian–Pacific plate boundary in South Island, New Zealand, has resulted in exhumation of a kilometre-wide mylonite zone in the hanging wall adjacent to the current brittle fault trace. The mylonites formed under amphibolite facies conditions at depths of ca. 25 km and have been uplifted during the past 5 Ma. A suite of 65–70 Ma pegmatite veins in the hanging wall Alpine schists has been progressively deformed within the mylonite zone and sheared out over a strike length of ca. 100 km. Measurements of the thickness distribution of the pegmatite veins within the non-mylonitised schists and at three localities within the progressively strained mylonites have been used to estimate strain values within the mylonites. The thicknesses approximate a log-normal distribution, with a mean value that is progressively reduced through the protomylonites, mylonites and ultramylonites. By assuming that the thickness distribution currently observed in the schists was the same for the pegmatites within the mylonites before strain, a model of deformation incorporating simple shear and simultaneous pure shear is used to strain the undeformed veins until a fit is obtained with the strained distributions. Shear strains calculated range from 12 to 22 for the protomylonites, 120 to 200 for the mylonites and 180 to 300 for the ultramylonites, corresponding to pure shear values of 1–3 in each case. These values are compatible with the strains predicted if most of the surface displacement on the fault over the past 5 Ma were accommodated within a 1–2-km-wide mylonite zone through the middle and lower crusts. The results suggest that processes such as erosional focussing of deformation and thermal weakening may cause intense strain localisation within the lower crust, with plate boundary deformation restricted to narrow zones rather than becoming increasingly distributed over a widening shear zone with depth.