现代地质
現代地質
현대지질
GEOSCIENCE-JOURNAL OF GRADUATE SCHOOL CHINA UNIVERSITY OF GEOSCIENCES
2013年
6期
1308-1315
,共8页
胡鸿飞%张永全%胡华斌%张超%张利忠
鬍鴻飛%張永全%鬍華斌%張超%張利忠
호홍비%장영전%호화빈%장초%장리충
闪长岩%地球化学特征%滴水沟岩体%内蒙古
閃長巖%地毬化學特徵%滴水溝巖體%內矇古
섬장암%지구화학특정%적수구암체%내몽고
diorite%geochemical characteristic%Dishuigou intrusion%Inner Mongolia
滴水沟闪长岩体位于华北板块北缘西段狼山构造带。结合前人的锆石 U-Pb 测年资料,可确定其形成于晚石炭世-早二叠世早期。岩石学及地球化学分析显示岩体属钙碱性系列,相对富集 Rb、Ba、Th、K、P 等大离子亲石元素,亏损 Nb、Ta、Ti 等高场强元素,具有低 Rb /Sr(0.05~0.10)值、高 Ba/Rb(11.45~22.16)值,且 A /CNK <1.1;REE 含量显示,滴水沟闪长岩体为轻稀土富集型,轻、重稀土元素高度分异,轻稀土元素发生明显的分馏作用,铕异常不明显(δEu =0.92~1.13),反映了俯冲带岩浆岩的特征,推测其物质来源为幔壳混源型。结合区域构造演化,认为其形成于活动板块边缘(碰撞前)火山弧环境,与晚石炭世晚期古亚洲洋板块向华北板块北缘西段的俯冲有关。
滴水溝閃長巖體位于華北闆塊北緣西段狼山構造帶。結閤前人的鋯石 U-Pb 測年資料,可確定其形成于晚石炭世-早二疊世早期。巖石學及地毬化學分析顯示巖體屬鈣堿性繫列,相對富集 Rb、Ba、Th、K、P 等大離子親石元素,虧損 Nb、Ta、Ti 等高場彊元素,具有低 Rb /Sr(0.05~0.10)值、高 Ba/Rb(11.45~22.16)值,且 A /CNK <1.1;REE 含量顯示,滴水溝閃長巖體為輕稀土富集型,輕、重稀土元素高度分異,輕稀土元素髮生明顯的分餾作用,銪異常不明顯(δEu =0.92~1.13),反映瞭俯遲帶巖漿巖的特徵,推測其物質來源為幔殼混源型。結閤區域構造縯化,認為其形成于活動闆塊邊緣(踫撞前)火山弧環境,與晚石炭世晚期古亞洲洋闆塊嚮華北闆塊北緣西段的俯遲有關。
적수구섬장암체위우화북판괴북연서단랑산구조대。결합전인적고석 U-Pb 측년자료,가학정기형성우만석탄세-조이첩세조기。암석학급지구화학분석현시암체속개감성계렬,상대부집 Rb、Ba、Th、K、P 등대리자친석원소,우손 Nb、Ta、Ti 등고장강원소,구유저 Rb /Sr(0.05~0.10)치、고 Ba/Rb(11.45~22.16)치,차 A /CNK <1.1;REE 함량현시,적수구섬장암체위경희토부집형,경、중희토원소고도분이,경희토원소발생명현적분류작용,유이상불명현(δEu =0.92~1.13),반영료부충대암장암적특정,추측기물질래원위만각혼원형。결합구역구조연화,인위기형성우활동판괴변연(팽당전)화산호배경,여만석탄세만기고아주양판괴향화북판괴북연서단적부충유관。
The Dishuigou dioritic intrusion is located in the Langshan arc at the northern margin of the North China Craton (NCC),Inner Mongolia.It is emplaced in the Late Carboniferous-Early Permian according to the previous zircon U-Pb dating data.In this paper,the major and trace (including rare earth)elements composi-tion of the Dishuigou diorite are reported.The result shows relatively enriched in large ion lithophile elements (LILE)such as the Rb,Ba,Th,K,and P,and depleted in high field strength elements (HFSE)such as the Nb,Ta,and Ti,and high Rb /Sr (0.05 -0.10)and Ba /Rb (11.45 -22.16)values,and low A /CNK (<1.1).In combination with the strong fractionation REE (LREE /HREE =2.97 -3.31)and LREE (La /Sm=2.75 -3.57),and insignificant Eu anomalies (δEu =0.92 -1.13),suggesting the dioritic intrusion formed in an arc environment and derived from mantle melt mixed with crust material during ascending.It is concluded that the southward subduction of the paleo-Asian oceanic slab in Late Carboniferous-Early Permian resulted in the formation of the Dishuigou dioritic intrusion based on the regional evolution the Langshan arc.