攀西地區(qū)基性—超基性巖巖石地球化學(xué)特征及巖漿演化過程分析
發(fā)布時(shí)間：2018-07-29 11:54
【摘要】：攀西基性-超基性巖體主要分布在揚(yáng)子克拉通西緣,受南北向斷裂帶控制,隸屬于峨眉山大火成巖省。巖體與峨眉山大火成巖省玄武巖形成時(shí)間均為晚二疊世,有一定相關(guān)性。本文選取攀西地區(qū)攀枝花、白馬和紅格三個(gè)區(qū)域的基性-超基性巖巖體作為典型代表,對其進(jìn)行詳細(xì)的野外地質(zhì)觀察、巖體地質(zhì)特征、巖相學(xué)特征以及全巖主微量元素地球化學(xué)特征分析,以解釋其巖漿演化的過程及與成礦的相關(guān)性。三個(gè)區(qū)域的含礦巖體在巖相帶劃分上略有不同,但總體上均表現(xiàn)出典型的韻律旋回特征。通過對三個(gè)代表巖體的不同巖石類型樣品的全巖主量測試結(jié)果顯示,它們均具有低硅,高鈦、鐵、鎂、鈣,低鈉、鉀的特征。Zr/Ti O2*0.0001vs.Si O2圖解、Nb/Y vs.Zr/Ti O2*0.0001圖解,AFM圖解顯現(xiàn)其屬于略偏亞堿性的拉斑玄武巖系列巖石。三個(gè)區(qū)域的微量元素地球化學(xué)特征顯示其富集輕稀土元素,虧損重稀土元素,富集部分大離子親石元素(Th、U),虧損一些高場強(qiáng)元素(Zr、Hf),暗示了它們可能具有相同的巖漿源區(qū),并且圖解趨勢與OIB洋島玄武巖有強(qiáng)相似性。巖體Si O2(32.59 65.81%)含量變化較大,Mg O(多數(shù)介于0.85 9.29%)含量普遍較低,低Cr(6.43-295ppm)等特征顯示其可能形成于相對演化的巖漿而并非地幔原生巖漿。微量元素特征顯示出明顯分異特征,強(qiáng)不相容元素較為富集,且微量元素蛛網(wǎng)圖顯示與麗江苦橄巖有一定相似性。麗江苦橄巖基本代表峨眉山玄武巖的原始巖漿,且其直接為地幔柱熔融結(jié)晶的產(chǎn)物,因此巖體的巖漿源區(qū)可能來自地幔柱。但是本文研究區(qū)巖體普遍不存在Nb、Ta的負(fù)異常,表明其地幔柱巖漿源區(qū)沒有受到地殼物質(zhì)的混染。巖體又均存在Zr和Hf元素負(fù)異常,表明巖漿在上升侵位過程中基本沒有經(jīng)歷地殼物質(zhì)的混染。巖體的Ti O2含量一般都高于2.5%,有時(shí)可高達(dá)8.44%,顯示其類似于高鈦玄武巖特征。Mg O與主要氧化物之間存在一定的相關(guān)性。Mg O與Ca O和Fe O呈正相關(guān),而同時(shí)與Si O2和Al2O3表現(xiàn)為負(fù)相關(guān),顯示巖漿演化過程中發(fā)生了單斜輝石(無斜方輝石)的分離結(jié)晶。部分巖石樣品中隨著Mg O含量的降低,Na2O、Al2O3、Ti O2和Si O2含量升高,顯示在超基性巖形成時(shí)以橄欖石的堆積為主,但是橄欖石一般僅存在于巖體底部,可能是分離結(jié)晶初期發(fā)生但并未在整個(gè)演化過程中起主要作用。Fe O與Ti O2正相關(guān)性,Al2O3和Ca O的無相關(guān)性,均表明巖漿演化過程中基本不存在斜長石的分離結(jié)晶。因此攀西巖體演化來源于地幔柱外圍地幔來源的富鈦鐵玄武質(zhì)巖漿。巖漿演化早期的富鐵鈦氧化物熔體向下集中,晚期巖漿再一次發(fā)生液態(tài)不混溶,從而結(jié)晶分異出巖體和礦體,并由重力作用影響最終聚集成礦。
[Abstract]:The basic-ultrabasic rock body of Panxi is mainly distributed in the western margin of Yangtze craton, controlled by the north-south fault zone, and belongs to the Emeishan great igneous province. The formation time of basalt in Emeishan igneous province is of late Permian, which is related to each other. In this paper, the basic-ultrabasic rock mass in Panzhihua, Baima and Hongge regions in Panzhihua, Panzhihua area and Hongge area is selected as the typical representative, and the detailed field geological observation and geological characteristics of the rock mass are carried out. In order to explain the process of magmatic evolution and the correlation with mineralization, the petrographic characteristics and the geochemical characteristics of the main trace elements in the whole rock are analyzed. The ore-bearing rock bodies in the three regions are slightly different in the division of lithofacies, but on the whole they all show typical rhythmic cycles. The main rock mass measurements of different rock types of the three represents rock mass show that they all have low silicon, high titanium, iron, magnesium, calcium and low sodium. The characteristics of potassium. Zr- / Ti O2*0.0001vs.Si O _ 2 diagram and NB / Y vs.Zr/Ti O _ 2O _ (0.0001) diagram show that it belongs to a slightly sub-alkaline tholeiite series. The geochemical characteristics of trace elements in the three regions indicate that they are enriched in light rare earth elements, depleted in heavy rare earth elements, enriched in some large ion lithophile elements (Thu) and depleted in some high field strength elements (ZrHf), suggesting that they may have the same magmatic source. The graphic trend is strongly similar to that of OIB basalt. The content of Sio _ 2 (32.59 ~ 65.81%) varies greatly (mostly between 0.85% and 9.29%), and the low Cr (6.43-295ppm) characteristics indicate that the Sio _ 2 (32.59 ~ 65.81%) may be formed from the relatively evolved magma rather than the mantle primary magma. The characteristics of trace elements show obvious differentiation, and the strongly incompatible elements are enriched, and the trace element spider webs show some similarity with the picrite in Lijiang. Lijiang picrite basically represents the primitive magma of Emeishan basalt and is directly the product of melting crystallization of mantle plume, so the magmatic source of the rock may come from mantle plume. However, there is no negative anomaly of NB ~ (2 +) Ta in the study area, which indicates that the mantle plume magmatic source area is not contaminated by crustal materials. There are also negative anomalies of Zr and HF elements in the rock mass, which indicates that the magma has not experienced crustal material mixing in the process of uplift emplacement. The content of TIO _ 2 in rock mass is generally higher than 2.5, and sometimes it can be as high as 8.44, which shows that there is a certain correlation between TIO _ 2 and main oxides, which is similar to that of high-titanium basalts. There is a positive correlation between MgO and Cao and Feo. At the same time, there is a negative correlation with Sio 2 and Al2O3, indicating that the separation and crystallization of clinopyroxene (no clinopyroxene) occurred during the magmatic evolution. The content of Na _ 2O _ 2O _ 3 Al _ 2O _ 3 TIO _ 2 and Sio _ 2 in some rock samples increases with the decrease of MgO content, indicating that olivine accumulation is dominant in the formation of ultrabasic rocks, but olivine usually exists only at the bottom of the rock mass. It is possible that the separation and crystallization occurred in the early stage of separation and crystallization but did not play a major role in the whole evolution process. There is no correlation between Fe O and TIO 2 positive correlation between Al 2O 3 and Cao, indicating that there is no separation and crystallization of plagioclase during magmatic evolution. Therefore, the evolution of Panxi pluton originated from the Black Tortoise magma rich in titanium from the mantle around the mantle plume. In the early stage of magmatic evolution, the iron-rich titanium oxide melts concentrate downwards, and the late magma once again produces liquid immiscible solution, thus crystallizing and differentiating the rock bodies and orebodies, and finally aggregating and forming ore bodies by the influence of gravity.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P588.1
本文編號(hào)：2152600
[Abstract]:The basic-ultrabasic rock body of Panxi is mainly distributed in the western margin of Yangtze craton, controlled by the north-south fault zone, and belongs to the Emeishan great igneous province. The formation time of basalt in Emeishan igneous province is of late Permian, which is related to each other. In this paper, the basic-ultrabasic rock mass in Panzhihua, Baima and Hongge regions in Panzhihua, Panzhihua area and Hongge area is selected as the typical representative, and the detailed field geological observation and geological characteristics of the rock mass are carried out. In order to explain the process of magmatic evolution and the correlation with mineralization, the petrographic characteristics and the geochemical characteristics of the main trace elements in the whole rock are analyzed. The ore-bearing rock bodies in the three regions are slightly different in the division of lithofacies, but on the whole they all show typical rhythmic cycles. The main rock mass measurements of different rock types of the three represents rock mass show that they all have low silicon, high titanium, iron, magnesium, calcium and low sodium. The characteristics of potassium. Zr- / Ti O2*0.0001vs.Si O _ 2 diagram and NB / Y vs.Zr/Ti O _ 2O _ (0.0001) diagram show that it belongs to a slightly sub-alkaline tholeiite series. The geochemical characteristics of trace elements in the three regions indicate that they are enriched in light rare earth elements, depleted in heavy rare earth elements, enriched in some large ion lithophile elements (Thu) and depleted in some high field strength elements (ZrHf), suggesting that they may have the same magmatic source. The graphic trend is strongly similar to that of OIB basalt. The content of Sio _ 2 (32.59 ~ 65.81%) varies greatly (mostly between 0.85% and 9.29%), and the low Cr (6.43-295ppm) characteristics indicate that the Sio _ 2 (32.59 ~ 65.81%) may be formed from the relatively evolved magma rather than the mantle primary magma. The characteristics of trace elements show obvious differentiation, and the strongly incompatible elements are enriched, and the trace element spider webs show some similarity with the picrite in Lijiang. Lijiang picrite basically represents the primitive magma of Emeishan basalt and is directly the product of melting crystallization of mantle plume, so the magmatic source of the rock may come from mantle plume. However, there is no negative anomaly of NB ~ (2 +) Ta in the study area, which indicates that the mantle plume magmatic source area is not contaminated by crustal materials. There are also negative anomalies of Zr and HF elements in the rock mass, which indicates that the magma has not experienced crustal material mixing in the process of uplift emplacement. The content of TIO _ 2 in rock mass is generally higher than 2.5, and sometimes it can be as high as 8.44, which shows that there is a certain correlation between TIO _ 2 and main oxides, which is similar to that of high-titanium basalts. There is a positive correlation between MgO and Cao and Feo. At the same time, there is a negative correlation with Sio 2 and Al2O3, indicating that the separation and crystallization of clinopyroxene (no clinopyroxene) occurred during the magmatic evolution. The content of Na _ 2O _ 2O _ 3 Al _ 2O _ 3 TIO _ 2 and Sio _ 2 in some rock samples increases with the decrease of MgO content, indicating that olivine accumulation is dominant in the formation of ultrabasic rocks, but olivine usually exists only at the bottom of the rock mass. It is possible that the separation and crystallization occurred in the early stage of separation and crystallization but did not play a major role in the whole evolution process. There is no correlation between Fe O and TIO 2 positive correlation between Al 2O 3 and Cao, indicating that there is no separation and crystallization of plagioclase during magmatic evolution. Therefore, the evolution of Panxi pluton originated from the Black Tortoise magma rich in titanium from the mantle around the mantle plume. In the early stage of magmatic evolution, the iron-rich titanium oxide melts concentrate downwards, and the late magma once again produces liquid immiscible solution, thus crystallizing and differentiating the rock bodies and orebodies, and finally aggregating and forming ore bodies by the influence of gravity.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P588.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
1 李佑國;許家斌;張?jiān)骆?王雪;;紅格礦床地質(zhì)地球化學(xué)特征與巖漿演化[J];礦物學(xué)報(bào);2013年S2期
2 汪云亮,張成江,修淑芝;玄武巖類形成的大地構(gòu)造環(huán)境的Th/Hf-Ta/Hf圖解判別[J];巖石學(xué)報(bào);2001年03期
，本文編號(hào)：2152600
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