發(fā)布時間：2018-05-17 21:46

  本文選題：黃岔巖體 + 贊皇雜巖　； 參考：《巖石學報》2017年09期

【摘要】：位于華北克拉通中部的贊皇雜巖中保留有豐富的新太古代-古元古代巖石記錄,是探究華北克拉通早期演化的重要地區(qū)之一。其中新太古代晚期TTG片麻巖和花崗巖的成因研究是探討贊皇雜巖構(gòu)造演化過程的關(guān)鍵。本文選擇出露于河北省邢臺市西部山區(qū)的黃岔花崗巖體進行研究。該巖體呈不規(guī)則的巖株產(chǎn)出,與周圍地層主要呈構(gòu)造接觸關(guān)系,局部侵入于官都群石英巖中。巖體主要由片麻狀、似斑狀二長花崗巖組成,邊緣相偶見細粒片麻巖包體,斑晶為長石和少量石英。LA-ICP-MS巖漿鋯石的~(207)Pb/~(206)Pb加權(quán)平均年齡為2488±6Ma,代表巖體的形成時代。由于黃岔巖體侵入于官都群,根據(jù)該花崗巖的時代可以限定官都群地層時代為太古代,而非古元古代。但官都群與贊皇群的關(guān)系還需要進一步研究。黃岔巖體具有高硅(Si O2=72.64%~74.16%)、富鉀(K_2O=3.53%~6.15%)、富堿(ALK=7.59%~9.07%)及鐵(Fe_2O_3T=1.84%~3.03%),貧鈣(CaO=0.67%~1.67%)、低鈦(TiO_2=0.18%~0.28%)、低鎂(MgO=0.31%~0.46%)的特征。巖石的稀土總量較高(ΣREE=364.2×10~(-6)~661.1×10~(-6)),輕重稀土元素分異較強烈((La/Yb)_N=18.7~29.8),并具有明顯的負Eu異常(Eu/Eu*=0.23~0.33)。微量元素中,富Zr、Zn、Nb、Ga、Y,而貧Sr、V、Cr、Co、Ni等元素,Rb/Sr比值較高,介于0.73~2.72之間,平均1.96。巖石Ga/Al值(2.75×10-4~3.11×10-4)高,全巖Zr飽和溫度為826~877℃,具有A型花崗巖特征。黃岔巖體鋯石εHf(t)為0.96~6.2,單階段和兩階段Hf模式年齡分別為2552~2746Ma和2576~2826Ma。黃岔巖體具有造山后A型花崗巖的特征,為2.7~2.5Ga的新太古代TTG片麻巖在造山后地殼拉張減薄初期的構(gòu)造背景下部分熔融所形成。~2.5Ga的堿性花崗巖在華北不同地區(qū)分布,并形成于伸展的構(gòu)造背景。該期堿性花崗巖的出現(xiàn),標志華北克拉通在太古宙末期已經(jīng)初步形成穩(wěn)定的克拉通。
[Abstract]:The Zanhuang complex located in the central part of North China Craton contains abundant records of Neo-Archaeo-Paleoproterozoic rocks and is one of the important areas to explore the early evolution of North China Craton. The genetic study of TTG gneiss and granite in late NeoArchean is the key to study the tectonic evolution of Zanhuang complex. In this paper, Huangcha granite body exposed in western mountainous area of Xingtai City, Hebei Province is selected for study. The rock body is formed irregularly, mainly in tectonic contact with the surrounding strata, and partly intruded into the quartz rock of the Guandu group. The rock mass is mainly composed of granitic, porphyry monzonitic granites, the marginal facies of which are occasionally fine-grained gneiss inclusions, and the porphyry rocks are feldspar and a small amount of quartz .LA-ICP-MS magmatic zircon. The weighted average age of 2488 鹵6Ma. Because the Huangcha rock intruded into the Guandu Group, the age of the granite can be defined as Archean, not Gu Yuan. However, the relationship between the official capital group and the Zanhuang group needs further study. The Huangcha rock mass has the characteristics of high Si-Si O _ 2 + 72.64 / 74.16, K _ 2O _ 3 ~ 3.53, K _ 2O _ 3, K _ 2O _ 3, alkali-rich ALK _ (7.59) and 9.07) and Fe2O3T ~ (1.84) ~ 3.03, Ca _ 2O _ (0.67) ~ (1.67), Ca _ 2O _ (0.67) ~ (1.67), Ti _ 2O _ 2O _ (2 / 0.18) 0.28T and mg _ 2O _ (0.31) ~ 0.46). The total amount of rare earth elements in rocks is relatively high (危 REE=364.2 脳 10 ~ (10) ~ (-6) ~ 661.1 脳 10 ~ (-1) ~ (10) ~ (-6) ~ (6), and the difference of heavy and heavy rare earth elements is stronger than that of La- / Yb ~ (2 +), and there is obvious negative EU / EU / EU / EU ~ (0.23) ~ (0.33). In the trace elements, Zirconium zinctorium (ZZN) and NbGA-GaOY are rich, but the ratio of Rb- / Sr is higher, ranging from 0.73 to 2.72, with an average of 1.96, which is poor in SrVV, Cr-CoC, Ni and other elements. The Ga/Al value of rock is 2.75 脳 10-4 (3.11 脳 10-4) and the saturation temperature of Zr in the whole rock is 826 ~ 877 鈩，

本文編號：1902974