共查询到19条相似文献，搜索用时 62 毫秒
1.
秦岭花岗岩揭示的秦岭构造演化过程——秦岭花岗岩研究进展 总被引：23，自引：0，他引：23
地壳形成和发展过程中花岗岩类的活动占有重要地位,花岗岩的广泛分布是大陆地壳尤其是造山带的重要特征之一.秦岭造山带中不同时代、不同成因、不同类型的花岗岩十分发育,其形成与造山带的发展演化息息相关,是秦岭造山带构造演化的真实记录.每次岩浆活动及其特定的岩石类型都表征了秦岭造山带板块构造发展的一个特定阶段和型式.深入研究秦岭花岗岩是阐明秦岭造山带形成、发展、演化和动力学过程的关键之一. 相似文献
4.
5.
6.
7.
东秦岭中段宽坪群秦岭群地层厘定 总被引：6，自引：0，他引：6
东秦岭中段商州地区下元古界宽坪群，秦岭群经１：５００００区调研究，宽坪自下而上建立了竹林沟组，四岔口组，广东坪组，麻街组，谢湾组等五个有序地层组和层位不确切的五峰山岩组。秦岭群属无序岩群，可分为变基性火山岩夹黑云变粒岩组合，黑云变粒岩夹条带状斜长角闪岩组合与浅粒岩夹大理岩组合，推断三种岩石组合可依次由老至新。 相似文献
8.
9.
东秦岭丹凤群秦岭群宽坪群关系新探 总被引：6，自引：0，他引：6
东秦岭泥盆系分布区以北依次排列着丹凤群、秦岭群、宽坪群三套变地层、之间被两条区域性大断裂所隔开。这三套地层沉积后均经历了三次强烈的褶皱，三次区域变质及三次韧性剪切，参考测年结果，提出了它们都是早元古代沉积的新认识，根据三套地层的沉积，岩性及地球化学特点，判定宽坪群为弧后大陆斜坡堆积，秦岭群与丹凤群为火山岛弧堆积，均属华北板块的前缘。 相似文献
10.
11.
秦岭造山带东段秦岭岩群的年代学和地球化学研究 总被引：20，自引：14，他引：6
对东秦岭地区的陕西省洛南县、宁陕县、长安县和河南省淅川县出露的四个秦岭岩群变质岩进行的岩石学和地球化学研究表明,样品主要由变质火山岩和变质沉积岩组成.详细的锆石U-Pb定年结果显示三个正变质岩均形成于新元古代早期(971～843Ma),而副变质岩中富集大量新元古代碎屑锆石,根据最年轻的谐和年龄(859Ma)和早古生代的变质年龄,推测其沉积时代为新元古代中晚期.因此,北秦岭南部的秦岭岩群的变质岩主要由新元古代早期的火成岩和新元古代中晚期的沉积岩组成.变质作用主要发生在加里东期,局部有燕山期的变质作用叠加.指示北秦岭的造山作用主要发生在早古生代.岩石地球化学研究还显示秦岭岩群的新元古代火山岩均形成于火山弧构造环境,沉积岩沉积于大陆弧-活动大陆边缘环境,指示秦岭造山带在新元古代早期是一个火山弧.秦岭岩群的火山岩和沉积岩在形成时代和构造环境方面与扬子克拉通西缘的特征非常相似,表明位于北秦岭造山带的秦岭岩群应归属于扬子克拉通陆块,是扬子北缘的一个大陆边缘弧. 相似文献
12.
分布于北秦岭造山带南部，夹持于商丹断裂带与朱夏断裂带之间的秦岭杂岩是秦岭造山带中最古老的前寒武纪基底块体之一。它是秦岭造山带中前寒武纪地壳形成与演化的地质记录，经历了晚元古代以来多旋回俯冲碰撞造山作用过程中多期构造热事件的改造。包含了大量反映秦岭造山带形成与演化的动力学过程地质信忠。虽然前人对秦岭杂岩已经进行了广泛深入研究，发表了大量的研究论著，提出了许多新认识和新见解，如从原秦岭群中解体出松树沟蛇绿岩片、峡河山群、古深成花岗片麻岩体等I高压变质岩(榴辉岩，高压麻粒岩)的发现；多期变形与变质特征的认识等。但由于秦岭杂岩问题的复杂性，某些认识或问题仍有待进一步研究探讨。其中(1)松树沟蛇绿岩片是否真正蛇绿岩?松树沟超镁铁质岩体与其围岩变质镁铁质岩是否同时代?它们的构造变形与变质历史是否相同?(2)峡河山群组成、分布、时代、构造意义及其与秦岭群片麻岩的关系；(3)秦岭岩群的组成、主变质期和变形期昀时代及性质；(4)晋宁期花岗岩带形成的构造背景及动力学意义；(5)已有同位素测年数据确切的地质意义；(6)高压交质岩的分布、产出状态、与围岩的关系、时代、成因及构造意义是秦岭杂岩研究中的基本问题。文中对上述有关问题进行了简要讨论，提出了今后秦岭杂岩研究的重点应放在构造事件、变质热事件、岩浆事件及其相互关系研究和这些地质事件的精确的同位素测年工作上。 相似文献
13.
位于东秦岭造山带商南—丹凤断裂带两侧的秦岭群与陡岭群之间的相关关系历来存在较大争议。它们是否属于同一块体,或者什么时候属于同一块体,又在什么时候裂解分开,不同学者从不同的角度给出了不同的认识。依据东秦岭地区1∶5万航空放射性资料和航空磁测资料分析认为:秦岭群以较平静的负磁场背景为主,对应航放总道及钍道为偏高场;而陡岭群则以磁异常幅值较大的正磁场为特征,对应航放总道及钍道为偏低场。综合东秦岭地区地震测深速度与视电阻率剖面分析结果研究认为,秦岭群的原岩组成以碳酸岩、泥质岩为主,形成于稳定大陆边缘的构造环境;而陡岭群的原岩组成以基性岩为主,形成于活动大陆边缘的构造环境。不少学者认为太古宙时期华北板块与扬子板块为一个统一陆块,秦岭群与陡岭群形成于2 000 Ma以前,但并没有给出太古宙统一板块的具体分裂时间。本研究推断至少在早元古代华北板块与扬子板块已经发生分离,并且它们之间可能已有大洋产生。 相似文献
14.
Metamorphic history and tectonic evolution of the Qinling Complex, eastern Qinling Mountains, China 总被引：6，自引：0，他引：6
YOU ZHENDONG HAN YUJING SUO SHUTIAN CHEN NENSONG ZHONG ZENQIU 《Journal of Metamorphic Geology》1993,11(4):549-560
Abstract The metamorphic history and tectonic evolution of the Qinling Complex is divided into formation and modification stages. During the Proterozoic formation stage, three deformational sequences are recognized. Andalusite–muscovite, sillimanite–muscovite and sillimanite–K-feldspar zones of amphibolite facies regional metamorphism are earlier than, or synchronous with the first or second phase of folding. Ductile shear zones were formed and Caledonian granites were emplaced during the modification stage. The granites superimposed contact aureoles (garnet–K-feldspar zone) on the regional metamorphic fabric.
Metamorphic reactions, P–T conditions of metamorphism and P–T–t paths were estimated by analysis of mineral textures and standard thermobarometric techniques. The P–T–t path of the Proterozoic tectonometamorphic cycle shows prominent clockwise decompression. The P–T–t path of the Caledonian tectonometamorphic cycle is characterized by an early rise of pressure and temperature, followed by isothermal decompression (rapid uplift) and finally with isobaric cooling.
The P–T–t paths of the two tectonometamorphic cycles reflect two major stages of collision and uplift in the evolution of the Qinling orogenic belt during the Proterozoic and Caledonian–Hercynian periods, respectively. 相似文献
Metamorphic reactions, P–T conditions of metamorphism and P–T–t paths were estimated by analysis of mineral textures and standard thermobarometric techniques. The P–T–t path of the Proterozoic tectonometamorphic cycle shows prominent clockwise decompression. The P–T–t path of the Caledonian tectonometamorphic cycle is characterized by an early rise of pressure and temperature, followed by isothermal decompression (rapid uplift) and finally with isobaric cooling.
The P–T–t paths of the two tectonometamorphic cycles reflect two major stages of collision and uplift in the evolution of the Qinling orogenic belt during the Proterozoic and Caledonian–Hercynian periods, respectively. 相似文献
15.
16.
17.
重新处理和解释叶县—南漳反射地震剖面,并综合利用油气勘探地震剖面,地震层析、大地电磁测深、地热流、气体测量等地球物理和地球化学数据,得到秦岭造山带岩石圈构造模型。识别出秦岭地壳不同时代的重要构造:(1)加里东期华北克拉通向秦岭微板块的俯冲,并造成中上地壳内华北地壳和北秦岭地壳形成锯齿状楔入构造。(2)印支—燕山期扬子克拉通与秦岭微陆块的对冲走滑软碰撞,形成了以南阳地区为中心由一系列规模宏大的逆冲断层组成的负花状构造。(3)白垩纪后,由正副片麻岩交互成层的结晶基底形成的穹隆。(4)盖在结晶基底上的近透明浅变质元古宙地层形成的褶皱基底。白垩纪后,秦岭地区和中国东部其他地区一样,岩石圈地幔遭受到软流圈上升形成蘑菇云构造,岩石圈活化,严重影响构造演化过程。 相似文献
18.
WANG Jingy REN Shenglian LI Jiahao LI Quanzhong SONG Chuanzhong LI Longmin LIN Shouf HUANG Yonglong HAN Xu LI Zhenqiang 《《地质学报》英文版》2017,91(1):351-352
<正>Objective The Qinling orogenic belt is a typical complex continental orogenic belt which has experienced multiperiod tectonic evolution and where some important tectonic belts formed.The Luoluan fault is one of the most important belts,which is the boundary fault of the North China Plate and the Qinling orogenic belt.The Shirenshan block is located in the north section between Luanchuan and Fangcheng of the Luoluan fault.The north part is 相似文献
19.
Paleozoic Tectonic Switch in the North Qinling Orogenic Belt: Constraints from the Paleozoic Granites from the Northern Qinling Migmatite Terrane 
下载免费PDF全文
下载免费PDF全文 The variations in source rocks and melting conditions of granites can provide essential clues for the crustal magmatic response in orogenic process. Based on geochronology, whole-rock and mineral chemistry, this paper reveals two different granites in the Northern Qinling migmatite complex, which reveal obvious differences in source region and melting condition. The older granodiorite (402 ± 0.8 Ma) displays typical Na-rich adakite affinity, i.e., high Na2O/K2O (2.04 to 2.64) and Sr/Y (96 to 117) ratios, they have relative evolved isotopic compositions (εNd(t) = ?0.52 to ?0.04; zircon εHf(t) = ?0.06 to +7.78). The younger leucogranite (371 ± 2 Ma) displays higher SiO2 (72.32 to 73.45 wt%), lower (TFeO + MgO + CaO + TiO2) contents (<2 wt%) and depleted Sr-Nd-Hf isotopic compositions (i.e., εNd(t) = +2.6 to +3.0; zircon εHf(t) = +5.94 to +14.12), as well as high 10000 × Ga/Al and TFeO/MgO ratios, indicating that they represent highly fractionated I-type granites that derived from melting of juvenile crust. The variations in source rocks and melting condition of the two granites indicating a tectonic switch from compression to extension in 400 to 370 Ma, this switch is later than that in the eastern section of the North Qinling, indicating a scissor collision process between the South Qinling and North China Craton (NCC) in Devonian era. 相似文献