地球化學(xué)特征及其地質(zhì)意義
(1. 中南大學(xué) 有色金屬成礦預(yù)測(cè)教育部重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083；
2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長(zhǎng)沙 410083)
摘 要: 為了解山東招遠(yuǎn)原疃金礦區(qū)內(nèi)煌斑巖成因及其形成環(huán)境，開(kāi)展了巖石地球化學(xué)研究。結(jié)果表明：礦區(qū)內(nèi)煌斑巖SiO2含量為49.29%~52.71%(質(zhì)量分?jǐn)?shù))、K2O/Na2O比值范圍為1.17~2.91，屬鉀質(zhì)鈣堿性系列；巖石稀土元素分配型式右傾，具弱負(fù)銪異常；Ti、Mn、Cu和Zn等過(guò)渡元素富集，Cr和Ni相對(duì)虧損。結(jié)合煌斑巖K-Ar全巖年齡(102.29~119.34 Ma)，認(rèn)為本區(qū)煌斑巖來(lái)源于富集地幔，與早期蘇魯洋板塊消減俯沖及太平洋洋殼熔融產(chǎn)生的富集流體均關(guān)系密切，其形成與華北克拉通中生代構(gòu)造體制轉(zhuǎn)折和巖石圈減薄事件有關(guān)，是膠東中生代大規(guī)模巖漿活動(dòng)的一部分。
關(guān)鍵字: 原疃；煌斑巖；地球化學(xué)；俯沖作用
Yuantuan gold ore district, Shandong Province, China
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:To investigate the genesis and forming environment of lamprophyres in Yuantuan gold ore district, the petrogeochemical study was carried out. The results show that the mass fraction of SiO2 changes from 49.29% to 52.71%, the ratio of K2O to Na2O changes from 1.17 to 2.91, belonging to kalium calc-alkaline series. The distribution of REE of samples is right deviation, with slightly negative Eu anomalies. The lamprophyres are characterized by enrichment in transitional elements, such as Ti, Mn, Cu, Zn and depletion in Cr and Ni. Combined with the age of the lamprophyres by K-Ar dating method (102.29−119.34 Ma), it is concluded that the lamprophyres of Yuantuan gold ore district originate from enriched mantle, closely associate with the fluid from early subduction of Sulu Ocean and melting of the Pacific Ocean Crust, and Mesozoic tectonic transition in North China craton and lithospheric thinning events, and it is part of large-scale Mesozoic magma activity of Jiaodong.
Key words: Yuantuan; lamprophyres; geochemistry; subduction
