摘要
湖北程潮铁矿是鄂东南矿集区内最大的矽卡岩型铁矿床。为了系统研究矿区内不同侵入体的成因,对程潮矿区内不同时代的侵入体进行了矿物学、地球化学和Sr-Nd-Pb同位素研究。矿区内花岗岩、石英二长斑岩、闪长岩中的黑云母成分特征暗示它们均为壳幔物质混合成因的镁质黑云母;与成矿相关的花岗岩、石英二长斑岩中原生黑云母矿物学成分显示出原始岩浆具有高氧逸度的特征,高氧逸度为磁铁矿的形成提供了有利条件。岩石地球化学特征研究表明,不同类型的岩石都具有富钾和准铝质的特征,富集Rb、Ba、K等大离子亲石元素和轻稀土元素,亏损Nb、Ta、Ti等高场强元素。矿区岩石的(87Sr/86Sr)i值为0.705 0~0.709 1,εNd(t)值为-14.16^-6.95,206 Pb/204 Pb值为17.636~18.919,207 Pb/204 Pb值为15.451~15.613,208Pb/204Pb值为37.833~39.556。矿物学、地球化学、Sr-Nd-Pb同位素特征暗示矿区岩体为富集地幔发生部分熔融并同化混染了不同比例下地壳物质的产物,早期闪长岩((140±1)Ma)比晚期花岗岩和石英二长斑岩((128±1)Ma)的源区有更多的地幔成分,花岗岩和石英二长斑岩与闪长岩具有相近的锆石饱和温度(平均值分别为783、788、765℃)。
The Chengchao iron deposit is the largest skarn iron deposit in the southeastern Hubei ore cluster,but the genesis of the intrusive rocks is poorly constrained.In this contribution,mineralogy, geochemistry and Sr Nd Pb isotope of different type intrusive rocks have been studied.The biotite in the granite,quartzmonzonite porphyry and diorite is high in Mg contents,indicating that they derived from the mixture of mantle and crust material.The oxygen fugacity of the primary biotite in the granite and quartzmonzonite porphyry associated with the iron mineralization is high,indicating that the granite and quartzmonzonite porphyry are more favorable for the iron mineralization.Different types of intrusive rocks dominantly exhibit high K2 O content and metaluminous,and characterized by enrichment in the large iron lithophile elements（e.g.Rb,Ba and K）and light rare earth elements,and depletion in the high field elements（e.g.Nb,Ta and Ti）.They have moderately high initial Sr（（87 Sr/86 Sr）i =0.705 0 0.709 1）and negtiveεNd （εNd （t）=-14.1 6 -6.95）,and ratios of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb are 17.636 18.91 9,15.45 1 15.613,37.833 39.556 respectively.Viewed comprehensively from mineralogical characteristics of minerals in and geochemical and Sr Nd Pb isotopic features of intrusive rocks,it can be concluded that the intrusive rocks in the deposit are originated from the partial melting of an enriched mantle source,and then followed by significant contamination of the lower crust material during the evolution of magma.140 Ma diorite probably contains more mantle components than the granite and quartz monzonite porphyry of 128 Ma.The average zircon saturation temperatures in the granite and quartz monzonite porphyry are 783℃ and 788℃,respectively,similar to that for the diorite （765℃）.
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2014年第6期1827-1855,共29页
Journal of Jilin University：Earth Science Edition
基金
国家"973"计划项目(2012CB416802)
国土资源部公益性行业项目(200911007-18)
中国地质调查局地质大调查项目(1212011120994)
