贛東北蛇綠混雜巖中尖晶石環(huán)帶特征及其地質(zhì)意義
發(fā)布時間：2019-07-06 08:26
【摘要】：本文對贛東北蛇綠混雜巖中環(huán)帶狀的尖晶石進(jìn)行了深入的礦物學(xué)研究,結(jié)合地幔橄欖巖和玄武巖進(jìn)行地球化學(xué)分析,并綜合尖晶石的共生礦物特征,進(jìn)而揭示尖晶石微區(qū)環(huán)帶特征與其所經(jīng)歷的深部地質(zhì)過程之間的耦合關(guān)系,探討其地質(zhì)意義。論文取得以下幾點認(rèn)識:(1)識別出了3種產(chǎn)狀的尖晶石:①部分蝕變狀尖晶石,呈黑色和紅褐色不規(guī)則狀,Cr#值為20.25~38.39,指示為深海橄欖巖的殘余體,估算部分熔融程度為8%~11%;②環(huán)帶狀尖晶石,呈粒狀分布在蛇紋巖中,Cr#值介于45.36~49.53之間,指示洋內(nèi)俯沖環(huán)境;③有孔狀尖晶石,呈浸染狀和粒狀,表面具孔隙發(fā)育,高Cr#值(介于48.39~69.90之間)特征反映島弧環(huán)境,指示后期碰撞造山作用;(2)環(huán)帶狀尖晶石的主、微量元素含量表明從核心到邊緣,Fe O、Ga、Ni和Ti含量增加,Al2O3、Mg O、Cr2O3、V、Co和Mn含量減少;(3)俯沖作用的流體交代導(dǎo)致了尖晶石環(huán)帶的形成,從核心到邊緣發(fā)生元素的重新分配。流體交代過程中會使尖晶石中的主要成分Al2O3和Mg O發(fā)生轉(zhuǎn)移,在這期間產(chǎn)生了綠泥石充填在孔隙中;隨著氧化流體滲透進(jìn)一步加強(qiáng),尖晶石空孔隙中富Cr2+和Fe2+的流體會導(dǎo)致尖晶石中八面體配位和四面體配位的Fe3+、Fe2+重新排序,同時Zn、Co、Mn和Fe2+等元素可進(jìn)入Mg2+空出的四面體配位中,而Ni2+、Ga3+、Sc3+和Ti4+等元素可進(jìn)入Al3+空出的八面體配位中,從核心向邊緣的規(guī)律分布導(dǎo)致環(huán)帶的形成;(4)流體在環(huán)帶尖晶石的形成上起到重要作用,而地幔橄欖巖中的流體來源與構(gòu)造環(huán)境息息相關(guān),研究表明贛東北蛇綠混雜巖中地幔橄欖巖具虧損地幔源區(qū)的特征,為原始地幔熔融殘留物,并顯示有陸源物質(zhì)的混染,可能受消減作用的影響;(5)根據(jù)尖晶石環(huán)帶特征及區(qū)域構(gòu)造過程,對尖晶石環(huán)帶成因認(rèn)識如下:1100Ma~1000Ma洋殼發(fā)育階段,具M(jìn)ORB特征的玄武巖產(chǎn)出,在洋中脊深海橄欖巖形成尖晶石;1000Ma~890Ma期間,伴隨古華南洋向揚(yáng)子塊體俯沖,處于島弧之下的地幔楔發(fā)生部分熔融,洋內(nèi)俯沖帶流體交代致使尖晶石發(fā)生部分蝕變形成環(huán)帶狀尖晶石,流體進(jìn)一步蝕變改造,并最終形成有孔狀尖晶石;890Ma~850Ma期間,洋殼進(jìn)一步俯沖使華夏板塊與揚(yáng)子板塊在紹興-江山-萍鄉(xiāng)一帶碰撞拼貼,產(chǎn)生的構(gòu)造應(yīng)力作用使贛東北蛇綠巖發(fā)生NW向褶皺變形,導(dǎo)致有孔狀尖晶石具裂隙發(fā)育;850Ma~800Ma階段區(qū)域發(fā)生大規(guī)模的巖漿活動,對尖晶石微區(qū)的影響不明。尖晶石具有巖石成因的指示意義,為探討蛇綠巖的成因提供直接的礦物學(xué)證據(jù)。本文對贛東北蛇綠混雜巖中環(huán)帶狀尖晶石的研究表明尖晶石對蛇綠巖的形成和演化過程具有記錄作用,可以反映巖石經(jīng)歷的深部地質(zhì)過程。此外,本文對環(huán)帶狀尖晶石只是初步研究,在后續(xù)研究工作中可以對尖晶石微區(qū)中的微量元素、同位素、流體來源做進(jìn)一步系統(tǒng)的分析研究,揭示尖晶石微區(qū)中元素的分布規(guī)律,限定流體性質(zhì)以及礦物形成時溫度、壓力、氧逸度等物理化學(xué)信息。
[Abstract]:In this paper, an in-depth mineralogical study of the banded spinels of the middle ring of the ophiolitic melange in the northeast of Jiangxi is carried out, and the geochemical analysis of the ground-derived peridotite and the basalt is carried out, and the characteristics of the intergrowth of the spinel are integrated. Furthermore, the coupling relation between the characteristics of the spinel micro-zone and its deep geological process is revealed, and its geological significance is discussed. The following recognition is made in this paper: (1) Three types of spinel are identified: a partially altered spinel, a black and reddish-brown irregular shape, a Cr # value of 20.25-38.39, a residual body indicated as deep-sea peridotite, an estimated partial melting degree of 8-11%, and a ring-like spinel, In the granites, the Cr # value is between 45.36 and 49.53, which indicates the subduction environment of the ocean; the pore-like spinel is in the form of disseminated and granular, and the surface has pore development, and the high Cr # value (between 48.39 and 69.90) reflects the island arc environment and indicates the post-collision orogeny; (2) The contents of the main and trace elements of the ring-shaped spinel show that the content of Fe O, Ga, Ni and Ti is increased from the core to the edge, and the content of Al2O3, Mg O, Cr2O3, V, Co and Mn is reduced; and (3) the subduction of the fluid has led to the formation of the spinel belt. The redistribution of elements from the core to the edge. During the fluid metasomatic process, the main components Al2O3 and Mg O in the spinel are transferred, during which the chlorite is filled in the pores, and as the oxidation fluid penetration is further strengthened, The rich Cr2 + and Fe 2 + in the spinel hollow pores can lead to the octahedral coordination of the spinel and the Fe3 + and Fe2 + re-ordering of the tetrahedra, while the elements such as Zn, Co, Mn and Fe 2 + can enter the tetrahedrally coordinated with Mg2 +, while Ni2 +, Ga3 +, elements such as Sc3 + and Ti4 + can enter the octahedral coordination vacated by Al3 +, and the distribution of the regular distribution from the core to the edge leads to the formation of the endless belt; and (4) the fluid plays an important role in the formation of the annular spinel, and the source of the fluid in the ground peridotite is closely related to the construction environment, The study shows that the characteristics of the ground-and-ground olive-rock in the North-East and North-East snake-green hybrid rock are characterized by the loss of the source region, which is the original melting residue, and shows that the mixed-dyeing of the land-source material can be affected by the reduction effect; and (5) according to the characteristics of the spinel belt and the process of the regional construction, The genetic understanding of the spinel belt is as follows: at the stage of the development of the oceanic crust at the stage of 1100 Ma ~ 1000 Ma, the basalt output with the characteristics of the MOB, the spinel in the deep-sea peridotite in the ocean, and the subduction of the Yangtze block with the southern ocean of the ancient China during the period of 1000 Ma ~ 890 Ma, and the partial melting of the geodesic wedge under the island arc. in that period of 890-850 Ma, the oceanic crust further subduction to make the Cathaysian plate and the Yangtze plate collide with the Yangtze plate in the area of Shaoxing-Jiangshan-Meixiang, The tectonic stress produced in the northeast of Jiangxi resulted in the NW-to-fold deformation of the ophiolite in the northeast Jiangxi, resulting in the fracture development of the pore-like spinels, and the large-scale magmatism in the region of the 850-800 Ma phase region, and the influence on the spinel micro-domains is unknown. The spinel has the indication of the origin of the rock, and provides a direct mineralogical proof for exploring the origin of the ophiolite. In this paper, the study of the banded spinels of the middle ring of the ophiolite in the northeast of Jiangxi shows that the formation and evolution of the spinel has a record effect on the formation and evolution of the ophiolite, which can reflect the deep geological process of the rock's experience. In addition, this paper is a preliminary study on the ring-shaped spinels. In the follow-up study, the trace elements, isotopes and fluid sources in the spinel micro-domains can be analyzed and studied, and the distribution rule of the elements in the spinel micro-domains is revealed. Physical and chemical information such as temperature, pressure, oxygen fugacity, etc. when the fluid property and the mineral formation are defined.
【學(xué)位授予單位】：東華理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P578.46;P588.1
本文編號：2510897
[Abstract]:In this paper, an in-depth mineralogical study of the banded spinels of the middle ring of the ophiolitic melange in the northeast of Jiangxi is carried out, and the geochemical analysis of the ground-derived peridotite and the basalt is carried out, and the characteristics of the intergrowth of the spinel are integrated. Furthermore, the coupling relation between the characteristics of the spinel micro-zone and its deep geological process is revealed, and its geological significance is discussed. The following recognition is made in this paper: (1) Three types of spinel are identified: a partially altered spinel, a black and reddish-brown irregular shape, a Cr # value of 20.25-38.39, a residual body indicated as deep-sea peridotite, an estimated partial melting degree of 8-11%, and a ring-like spinel, In the granites, the Cr # value is between 45.36 and 49.53, which indicates the subduction environment of the ocean; the pore-like spinel is in the form of disseminated and granular, and the surface has pore development, and the high Cr # value (between 48.39 and 69.90) reflects the island arc environment and indicates the post-collision orogeny; (2) The contents of the main and trace elements of the ring-shaped spinel show that the content of Fe O, Ga, Ni and Ti is increased from the core to the edge, and the content of Al2O3, Mg O, Cr2O3, V, Co and Mn is reduced; and (3) the subduction of the fluid has led to the formation of the spinel belt. The redistribution of elements from the core to the edge. During the fluid metasomatic process, the main components Al2O3 and Mg O in the spinel are transferred, during which the chlorite is filled in the pores, and as the oxidation fluid penetration is further strengthened, The rich Cr2 + and Fe 2 + in the spinel hollow pores can lead to the octahedral coordination of the spinel and the Fe3 + and Fe2 + re-ordering of the tetrahedra, while the elements such as Zn, Co, Mn and Fe 2 + can enter the tetrahedrally coordinated with Mg2 +, while Ni2 +, Ga3 +, elements such as Sc3 + and Ti4 + can enter the octahedral coordination vacated by Al3 +, and the distribution of the regular distribution from the core to the edge leads to the formation of the endless belt; and (4) the fluid plays an important role in the formation of the annular spinel, and the source of the fluid in the ground peridotite is closely related to the construction environment, The study shows that the characteristics of the ground-and-ground olive-rock in the North-East and North-East snake-green hybrid rock are characterized by the loss of the source region, which is the original melting residue, and shows that the mixed-dyeing of the land-source material can be affected by the reduction effect; and (5) according to the characteristics of the spinel belt and the process of the regional construction, The genetic understanding of the spinel belt is as follows: at the stage of the development of the oceanic crust at the stage of 1100 Ma ~ 1000 Ma, the basalt output with the characteristics of the MOB, the spinel in the deep-sea peridotite in the ocean, and the subduction of the Yangtze block with the southern ocean of the ancient China during the period of 1000 Ma ~ 890 Ma, and the partial melting of the geodesic wedge under the island arc. in that period of 890-850 Ma, the oceanic crust further subduction to make the Cathaysian plate and the Yangtze plate collide with the Yangtze plate in the area of Shaoxing-Jiangshan-Meixiang, The tectonic stress produced in the northeast of Jiangxi resulted in the NW-to-fold deformation of the ophiolite in the northeast Jiangxi, resulting in the fracture development of the pore-like spinels, and the large-scale magmatism in the region of the 850-800 Ma phase region, and the influence on the spinel micro-domains is unknown. The spinel has the indication of the origin of the rock, and provides a direct mineralogical proof for exploring the origin of the ophiolite. In this paper, the study of the banded spinels of the middle ring of the ophiolite in the northeast of Jiangxi shows that the formation and evolution of the spinel has a record effect on the formation and evolution of the ophiolite, which can reflect the deep geological process of the rock's experience. In addition, this paper is a preliminary study on the ring-shaped spinels. In the follow-up study, the trace elements, isotopes and fluid sources in the spinel micro-domains can be analyzed and studied, and the distribution rule of the elements in the spinel micro-domains is revealed. Physical and chemical information such as temperature, pressure, oxygen fugacity, etc. when the fluid property and the mineral formation are defined.
【學(xué)位授予單位】：東華理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P578.46;P588.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 胡世玲,郝杰,李曰俊;江西德興西灣鈉長花崗巖的激光質(zhì)譜~(40)Ar/~(39)Ar等時年齡[J];中國區(qū)域地質(zhì);1998年01期
，本文編號：2510897
本文鏈接：http://sikaile.net/kejilunwen/diqiudizhi/2510897.html
最近更新
教材專著
