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1.
麻山杂岩的变质-混合岩化作用和花岗质岩浆活动 总被引：7，自引：3，他引：4
在黑龙江佳木斯地块麻山杂岩中可分别有高级和中级变质作用部分,两处均可见混合岩化作用。通过混合岩浅色脉体或花岗质脉体中的长石自形晶、斜长石周围的钠长石净边、黑云母向角闪石的转化等现象表明混合岩化作用主要表现为深部岩浆的注入,而不仅是高级变质之后的近原地深熔作用所致,高级变质与相关的深熔作用所致混合岩化在区域上的分布是有限的,集中于西麻山的高级区;而注入式混合岩化是普遍的,其产出可遍布所有麻山杂岩的出露区,在麻粒岩相和角闪岩相部位均可出现。早期麻粒岩相变质与后期混合岩化作用应是相互独立的构造或热事件;注入式混合岩化引起了中级变质作用和高级区的退变质作用,注入混合岩化作用的时代约为500Ma;中级变质作用是注入混合岩化的结果,而不是混合岩化的原因。与注入混合岩相关的花岗岩虽然表现出一些S型花岗岩的特征,但根据矿物组合、地化性质的综合分析,更可能是富钾及钾长石斑晶的钙碱性花岗岩类,属于I型花岗岩,形成于挤压向引张转化的过程中。麻山杂岩的变质与混合岩化特征表明,以西伯利亚古陆为中心的南部边缘发生了与冈瓦纳陆块内泛非事件类似的构造活动,只不过这里的规模略小,在变质之后迅速发生了构造体系的转换,而形成大量花岗质岩浆活动。 相似文献
2.
张宣高变质花岗岩－绿岩带内早期花岗质侵入体是以英云间长岩和花岗间长岩为主体的ＴＴＧ岩系，经历了麻粒岩相高级变质作用的改造，已变质成以含紫苏辉石为特征的片麻岩类岩石。麻粒岩相峰期变质作用的时代为２３９０±１９Ｍａ。紫苏花岗岩属典型岩浆成因侵入岩，其侵位成岩时代为２３９０±２４Ｍａ，是区域麻粒岩相峰期变质作用期间长英质熔浆直接结晶的产物。钾质花岗岩类具多种不同的岩石类型，为一系列小规模的富钾质花岗岩侵入体，是与紫苏花岗岩同一构造岩浆活动事件的产物。麻粒岩相峰期变质作用、岩浆活动时代的一致性，表明了本区太古宙末－古元古代早期，由于大规模构造运动，麻粒岩相变质作用由峰期变质条件向相对低温低压条件演化、花岗岩－绿岩带基底岩石由地壳深部向地壳浅部抬升、并同时伴随紫苏花岗岩及钾质花岗岩等大规模岩浆侵入活动的区域地壳演化规律。 相似文献
3.
本区经历四期变质作用,太古宙上壳岩系麻粒岩相变质、晚太古宙英云闪长岩高角闪岩相变质、早元古宙紫苏花岗岩类低角闪岩相变质和元古宙绿片岩相变质。麻粒岩相变质期可分三个阶段,早期角闪岩相、峰期麻粒岩相和晚期角闪岩相,其P-T-t轨迹为逆时针,与IBC型轨迹相似。导致麻粒岩相变质作用的热源为英云闪长质岩浆的垫托作用,形成于岛弧或活动大陆边缘。区内广泛发育的钾长花岗岩与晚太古宙高角闪岩相变质作用晚期的深熔作用有关。 相似文献
4.
麻山杂岩的两种变质作用及其与花岗岩的关系 总被引：2，自引：1，他引：1
在黑龙江佳木斯地块麻山杂岩中识别出麻山杂岩中具有两种类型的变质作用:早期局部的麻粒岩相变质作用(M1)和伴随的无水深熔作用(>530Ma),即狭义的麻山群高级变质作用,变质岩多以残留块体形式散布于后期混合岩或花岗岩之中;麻粒岩相变质之后由于广泛的岩浆活动,造成了强烈的混合岩化作用(500Ma)和相应大范围的晚期角闪岩相变质作用(M2)。角闪岩相和麻粒岩相变质并非带状递进变化,而是在时空上均有差异的两种变质作用。混合岩化过程中的富水流体对早期"干"岩石进行了明显的退变质改造,从而造成高级变质岩变质结构的复杂性。此外,含水花岗岩的侵位对先期麻粒岩相变质成因锆石同位素体系有重置作用,使得早期的变质年龄难以测定。麻山杂岩的变质-花岗岩关系与东南极普里兹带有类似之处,在变形-变质之后迅速发生了构造体系的转换,出现了新的岩浆活动,只是花岗岩发育强度有所不同,反映了两地构造演化细节上的差异。西伯利亚古陆南缘及中亚造山带内部的一些微陆块发生了与冈瓦纳陆块内泛非事件类似的构造-热-岩浆事件,因此,中亚造山带内部的佳木斯地块及其他类似的微陆块与冈瓦纳古陆边缘活动带具有相似的构造性质。 相似文献
5.
东喜马拉雅构造结南迦巴瓦群高压麻粒岩中含石榴石花岗岩脉锆石SHRIMP U-Pb定年及其与折返作用 总被引：13，自引：10，他引：3
东喜马拉雅构造结核部的南迦巴瓦群是经历了高压麻粒岩相峰期变质、角闪岩相退变质和强烈混合岩化作用形成的以含有高压麻粒岩透镜体或夹层为特色的变质岩组合。地质地球化学研究表明产于退变质高压麻粒岩中的含石榴石花岗岩脉具有高钾、富铝、轻稀土强烈富集、分馏程度很高、重稀土相对亏损、Eu强烈亏损、大离子亲石元素及放射性元素相对原始地幔值强烈富集、Rb/Sr1.4的特征。利用花岗岩的主要成分及锆的含量估算的岩浆初始温度为792～801℃,略低于南迦巴瓦群的峰期变质温度850℃。锆石SHRIMPU-Pb定年结果显示锆石核部年龄集中在519～525Ma之间,揭示出印度地块经历泛非期构造运动改造的痕迹。锆石边部主要存在39～44Ma、24～25Ma和7.3Ma三个年龄段,前者代表了花岗岩浆的侵位时代,第二个年龄段是对MCT和STDS构造热事件改造的反映,后者揭示出构造-浅表反馈作用的信息。说明含石榴石花岗岩脉是在南迦巴瓦群折返过程中近等温降压条件下地壳岩石发生"干"深熔作用形成的高钾过铝质钙碱性花岗岩,以及南迦巴瓦群在经历峰期变质作用后很快就开始折返,并在后碰撞过程中经历了藏南拆离系(STDS)和主中央冲断带(MCT)构造事件及后期构造-浅表反馈作用的影响。 相似文献
6.
冀东地区麻粒岩相变质作用的演化 总被引：1，自引：2，他引：1
据冀东迁安－遵化一带麻粒岩相区的变质岩石、变质矿物及其组构特征、变质作用的温度、压力条件，结合同位素年代学资料，以及岩浆作用、构造变形作用和变质作用之间的关系，可将本区太古代变质作用划分为两期。太古代第一期变质作用只限于表壳岩包体岩石中，变质级为高角闪岩相和辉石麻粒岩相，第二期变质作用发生在晚太古代，早期变质阶段是在紫苏花岗岩侵位以后发生的辉石麻粒岩相变质作用，晚期变质阶段发生在稍后侵位的基性侵入岩体、英云闪长岩、奥长花岗岩等深成侵入体中，变质级达角闪麻粒岩相。早元古代第一期角闪石榴二辉麻粒岩型岩脉，遭受了辉石麻粒相变质作用，第二期角闪石榴斜长辉石岩型岩脉经历了角闪麻粒岩相变质作用。这些变质作用在早期岩石中都有不同程度的叠加。麻粒岩相变质作用的温度在７００℃～９２０℃，压力在０．８８～１．１４ＧＰａ。变质作用的ＰＴｔ演化呈现了逆时针近等压冷却的轨迹 相似文献
7.
陕西勉略宁区鱼洞子花岗岩-绿岩地体地质特征及其含金性 总被引：8，自引：0，他引：8
鱼洞子绿岩为笔者在西秦岭南缘地区首次发现的最老含金矿源层。通过阁老岭—鱼洞子地块的详细研究认为,其岩石组合由上壳岩系列的绿岩和花岗片麻岩系列组成。在绿岩建造下部的碎裂混合岩化斜长角闪岩中选获锆石,测得U-Pb年龄为2657±9Ma,因此确定其时代为晚太古代。绿岩建造是本区最主要的含金矿源层。金矿化与构造演化关系密切,大致分为3个阶段:(1)绿岩建造形成阶段。绿岩建造下部的基性火山岩及上部的磁铁石英等主要的金源岩形成。(2)低角闪岩相变质、深部熔融及花岗岩化阶段。伴随低角闪岩相变质及花岗岩化作用,使绿岩建造的金活化并向花岗岩化带的边部及顶部迁移、聚集。(3)褶皱造山和钾长花岗岩形成阶段。主要表现在区内韧性剪切和大型褶皱作用,并伴随有区域绿片岩相的退化变质作用,是本区重要的金的成矿期。此阶段并伴有角闪岩脉侵入,其全岩K-Ar释稀法年龄为2038±30Ma,标志地体克拉通化最终完成。 相似文献
8.
深熔作用是大陆地壳分异、元素迁移富集和混合岩化作用的主要机制和关键地质过程.吉南地区出露的太古宙基底普遍经历了角闪岩相-麻粒岩相变质及深熔作用,长英质淡色体及淡色花岗岩广泛分布.吉南和龙花岗-绿岩地体出露的太古宙变质石英闪长岩及相关的长英质浅色体和含斜方辉石(角闪石)淡色伟晶花岗岩的野外地质特征、相互关系及岩相学特征指... 相似文献
9.
辽西变质杂岩特征和变质作用的PTt轨迹 总被引：1，自引：0，他引：1
辽西早太古宙变质杂岩是由85%～90%长英质片麻岩(主要是英云闪长岩—花岗间长岩—花岗岩组合(简称TTG)的深成花岗杂岩)和10%～15%上壳岩(包括层状火山—沉积岩、脉岩及基性超基性侵入岩等)组成.斜长角闪岩和基性麻粒岩可与世界变质拉斑玄武岩对比.TTG岩石可能由中酸性岩浆与围岩熔融而成.麻粒岩相是中压区域高温变质作用的产物,变质作用的演化为退变质、近等压冷却(IBC)反时针型的PTt轨迹. 相似文献
10.
Schirmacher山区的前寒武纪基底岩石位于南纬70°44′33″～70°46′30″和东径11°22′04″～11°54′00″,岩石表现出几个阶段的褶皱作用、剪切带的发育以及两期截然不同的变质-混合岩化事件。区内的岩石经受了初期阶段的麻粒岩相变质作用及紧随其后的紫苏花岗岩化。非常粗粒的含紫苏辉石、石榴石的伟晶岩呈平行条带状侵入,并使岩石转变成为混合岩。这一事件之后为角闪岩相退化变质作用与区域花岗岩化,形成了区内的主体长英片麻岩。某些变斑晶具有紧闭微褶的Si,它主要由针状矽线石包体反映出来。这些早期微褶 相似文献
11.
Mode of occurrence and significance of jadeite in the Kamuikotan metamorphic rocks, Hokkaido, Japan 总被引：3，自引：0，他引：3
MASASHI TAKAYAMA 《Journal of Metamorphic Geology》1986,4(4):445-454
Abstract In the Kamuikotan zone, jadeite occurs in pelitic rocks, in metaplagiogranites, in veins in amphibolites and mafic sedimentary rocks, and in jadeite-albite rocks. In the first and second types, jadeite is associated with quartz, and is often in direct contact with it. However, such rock-types never occur as part of the coherent metamorphic sequence, but are found only as exotic blocks enclosed in serpentinite. Thus, jadeite + quartz-bearing assemblages are not regarded as representative of the Kamuikotan metamorphism. Lawsonite and aragonite, however, commonly do occur in the Kamuikotan metamorphic rocks, and this metamorphism belongs to a subfacies of the lawsonite-albite facies, in which aragonite is stable. The serpentinite matrix which carried jadeite + quartz-bearing pelites and metaplagiogranites into the metamorphic sequence is interpreted as a tectonic rather than a sedimentary melange. 相似文献
12.
I. A. Tararin 《Petrology》2008,16(2):193-209
Geological, mineralogical, and geothermobarometric data testify that the regional metamorphism of the terrigenous protolith of the Kolpakovskaya Series, which composes the stratigraphic basement of the Kamchatka Median Crystalline Massif, corresponded to the kyanite mineral subfacies of the amphibolite facies at temperatures of 560–660°C and pressures of 5.9–6.9 kbar. This metamorphism predetermined wide kyanite development in high-Al garnet-biotite plagiogneisses. The younger granitization and migmatization of the plagiogneisses took place at a decrease in the pressure (depth), as follows from the textures of kyanite reaction replacement by andalusite in both the metamorphic rocks and the vein synmetamorphic granitoids and pegmatites. The temperature of the granitization and migmatization processes in the plagiogneisses was estimated at 620–650°C, and the pressure was evaluated at 1.9–3.0 kbar. Acid leaching that accompanied the granitization and migmatization processes resulted in the intense replacement of biotite by sillimanite (fibrolite) and, to a lesser degree, muscovite in the metamorphic and vein magmatic rocks. The highest temperature orthopyroxene-cordierite-biotite-orthoclase-plagioclase-quartz mineral assemblages were determined to have been formed in the Kolpakovskaya Series at a temperature of 830–840°C not by the regional metamorphism but in contact aureoles around gabbro-granitoid intrusions of the Lavkinskii intrusive complex of Oligocene-Miocene age in garnet-biotite and kyanite-garnet-biotite plagiogneisses of the amphibolite facies and cannot thus be regarded as evidence of an early granulite stage in the metamorphism of these rocks. 相似文献
13.
The rocks of the Fana area have been mapped as Sagevika Group (basement in the area), Fana Group (metasediments and granites), Saganes Group (may be Cambro-Silurian?), and Lysekloster Zone, each forming a tectonic unit. The Precambrian rocks of the Fana Group after attaining amphibolite-granulite facies metamorphism (first episode) have been subjected to regional folding which initiated mobilisation and anatexis (second episode), the latter phenomenon is early Caledonian. The rocks of Fana Group present a complete petrologic sequence from meta-arkose to anatectic granite, and occur as a folded plate occupying highest structural position in the area. Post-anatectic deformations are seen as snyformal structure, low angle shear zones and mylonitisation (third episode). 相似文献
14.
J.W. Granath 《Precambrian Research》1975,2(1):71-91
The Precambrian metamorphic complex in the southern portion of Wind River Canyon is interpreted as being a fragment of an Archaean greenstone belt. The sequence is composed of meta-sediments inferred to have been various types of pelites and psammites, including graywackes and shales, and a silicate facies banded-iron formation. Meta-volcanics are represented by massive amphibolites.The area has undergone three periods of roughly coaxial folding that represent a single tectonic pattern. A period of intrusion of leucogranite with associated pegmatites separates the first two periods of deformation. These rocks appear to have been derived anatectically from sialic material at greater depth, suggesting the possibility of a sialic basement on which the greenstone belt rocks accumulated. Boudinage of the country rocks can be correlated with either or both of the first two folding episodes, and boudinage of the intrusive rocks occurred with different styles in the axial surfaces of the second and third generation folds.One period of amphibolite-facies metamorphism corresponds to the first and second deformational phases. Minor retrograde effects, fracture fillings, and small-scale metasomatism occurred either in the waning stages of the metamorphism or during a minor subsequent thermal event.Numerous Archaean ages from the Wyoming Precambrian province place Wind River Canyon in a region where examples of such greenstone belts might be expected. As no young intrusive or tectonic events have been reported from the area, the youngest deformational features discussed are considered to be not much younger than reported radiometric dates and therefore not of regional significance. 相似文献
15.
阿尔泰海西造山带区域变质作用类型与地壳演化 总被引：17，自引：0，他引：17
新疆阿尔泰海西造山带主要发育两期区域变质作用.第一期变质作用属于区域低温动力变质作用类型,以形成低绿片岩相矿物组合为特征,变质温度较低,而应力作用较强,是造山作用初期热流活动较弱,构造变形强烈环境下的产物.第二期变质作用属于区域动力热流变质作用类型,以形成典型的递增变质带为特征.这一期代表造山作用主期热流活动强烈,伴随有构造变形和岩浆活动.不同的变质作用类型代表了不同的大地构造环境,记录了造山带的演化历史和动力学过程. 相似文献
16.
桐柏-大别山区高压变质相的构造配置 总被引：18，自引：3，他引：15
作为华北和扬子陆块间的碰撞造山带桐柏大别山区以发育高压、超高压变质带为特征,从南到北变质相从低级到高级,代表俯冲带深度不同的变质产物,整体形成高压变质相系列。不过现今各变质相岩石的分布极受后期地壳规模的伸展构造控制,大别杂岩的穹隆作用更使高压变质相带的空间分布复杂化。超高压变质岩今日多呈大小不等的块体嵌布于相对低压的大别杂岩之内,造山带根部物质的热软化,使许多深层地幔物质得以像挤牙膏一样挤出于大别杂岩内。它们之中广泛发育着减压退变质的显微结构,与大别杂岩内一些麻粒岩相表壳岩所保存的减压退变质证迹一样,同是挤出作用和碰撞后隆升的构造证迹。高压相系的发育使南桐柏山和大别山迥然不同于桐商（ 商丹） 断裂以北的北秦岭北淮阳变质带。新近发表的同位素年代学（４０Ａｒ ３９ Ａｒ） 资料：３１６ ～４３４ Ｍａ ,已证明北秦岭是古生代变质带,它与桐柏－ 大别印支期碰撞造山带差异甚大。这两个变质地温梯度差异甚大的变质地体的拼合,说明华北和扬子陆块碰撞的主缝合带是商丹－ 桐商断裂带 相似文献
17.
澜沧群变质变形过程的厘定有助于揭示澜沧江构造带的演化历史.通过对双江-惠民地区出露的中-低绿片岩相变质岩系与高压变质岩系的"构造-变质"双重解析,发现澜沧群变质岩系:（1）以挤压体制下的褶劈理S2为区域性面理,浅变质岩系中石英脉条带代表的面理S1与层理S0产状一致,并在第2期强烈压扁后与S2近平行;（2）构造样式与变质变形期次在研究区域内基本一致,表现为二叠纪-三叠纪两期次中深构造层次透入性变形为侏罗纪-新生代浅-表层次变形所叠加;（3）高压变质岩记录了两个期次的深层次构造变形,电气石与石榴石变斑晶具有明显的两阶段生长模式,核部（M1aD1a）可能代表了峰期榴辉岩相变质作用,边部代表折返过程中的蓝片岩相（M1bD1b）阶段.高压变质岩与浅变质岩第2期（M2D2）构造层次及变形样式一致,代表折返后的挤压拼贴过程,两者的剪切型褶劈理S2均指示上盘S向的剪切滑动.结合新生代三江地区发生的近90°块体旋转,恢复第2期为上盘指向E的逆冲剪切作用.通过对幸福变质石英砂岩白云母、小黑江多硅白云母和蓝闪石的40Ar-39Ar定年,以及对前人小黑江蓝闪石40Ar-39Ar年龄的重新解释,共厘定出澜沧群4个构造阶段:（1）高压变质岩第1期晚期（D1b）蓝片岩相变质作用（~250 Ma）;（2）第2期（M2D2）中层次挤压（215~214 Ma）;（3）浅变质岩系第3期早期（D3a）N-S向纵弯褶皱（111.9~103.7 Ma）与晚期（D3b）逆冲（~82.28 Ma）;（4）第4期近E-W向纵弯褶皱（新生代,很可能晚于59.18 Ma）. 相似文献
18.
新疆阿尔泰阿祖拜地区发育两种类型区域变质作用,第一种为区域低温动力变质作用,第二种为区域动力热流变质作用.阿祖拜地区递增变质带是后者的典型代表之一,从花岗岩体外接触带依次发育矽线石-堇青带、红柱石-十字石带、黑云母-石榴石带,递增变质作用强度呈逐渐减弱趋势.结合变形变质作用特征和同位素年龄,可识别出3个变形变质阶段.早期阶段以区域低温动力变质作用为主,形成绿片岩相变质岩石组合;峰期阶段为区域动力热流变质作用,形成典型的递增变质带;晚期阶段则属退化变质作用.不同变质作用类型代表了不同大地构造环境,记录了造山带演化历史年和动力学过程. 相似文献
19.
John N. Aleinikoff Ian S. Williams William Compston John S. Stuckless Ronald G. Worl 《Contributions to Mineralogy and Petrology》1989,101(2):198-206
Gneissic rocks that are basement to the Late Archean granites comprising much of the Wind River Range, west-central Wyoming,
have been dated by the zircon U-Pb method using both conventional and ion microprobe techniques. A foliated hornblende granite
gneiss member from the southern border of the Bridger batholith is 2670±13 Ma. Zircons from a granulite just north of the
Bridger batholith are equant and faceted, a typical morphology for zircon grown under high grade metamorphic conditions. This
granulite, which may be related to a second phase of migmatization in the area, is 2698±8 Ma. South of the Bridger batholith,
zircons from a granulite (charnockite), which is related to an earlier phase of migmatization in the Range, yield a discordia
with intercept ages of about 2.3 and 3.3 Ga. However, ion microprobe analyses of single zircon grains indicate that this rock
contains several populations of zircon, ranging in age from 2.67 to about 3.8 Ga. Based on zircon morphology and regional
geologic relationships, we interpret the data as indicating an age of ≃3.2 Ga for the first granulite metamorphism and migmatization.
Older, possibly xenocrystic zircons give ages of ≃3.35, 3.65 and ≃3.8 Ga. Younger zircons grew at 2.7 and 2.85 Ga in response
to events, including the second granulite metamorphism at 2.7 Ga, that culminated in the intrusion of the Bridger batholith
and migmatization at 2.67 Ga. These data support the field and petrographic evidence for two granulite events and provide
some temporal constraints for the formation of continental crust in the Early and Middle Archean in the Wyoming Province. 相似文献
20.
The metasedimentary rocks of the area around Mangpu constitute a portion of the hinge zone of the northern limb of the major synform of Lower Darjeeling Himalaya. The rocks display evidences of multiple deformation and at least three major phases of deformation have been recognized. The time relations between the phases of deformation (D1, D2, D3) and metamorphic crystallization reveal a single major prograde metamorphic event that initiated with the D1 deformation and finally outlasted it. The earlier phase of this metamorphism is essentially regional syn-tectonic lowgrade (greenschist facies) which may be designated (M1, early). This was followed by regional static metamorphism (M1, late) in the post-tectonic phase between D1 and D2 deformations (upper green schist and amphibolite facies). This M1 metamorphism is superposed by later retrogressive metamorphism (M2) during the D2 and D3 deformations (lower greenschist facies). Within the study area four isograds have been delineated by the first appearance of index minerals in the pelitic schists and gneiss which display Barrovian type of metamorphism. 相似文献