西北大学学报（自然科学版）
西北大學學報（自然科學版）
서북대학학보（자연과학판）
JOURNAL OF NORTHWEST UNIVERSITY(NATURAL SCIENCE EDITION)
2010年
1期
111-120
,共10页
张宏法%陈刚%鲍洪平%王润三%马占荣%彭天朗
張宏法%陳剛%鮑洪平%王潤三%馬佔榮%彭天朗
장굉법%진강%포홍평%왕윤삼%마점영%팽천랑
紫金山%火山机构%鄂尔多斯东缘%华北%山西临县
紫金山%火山機構%鄂爾多斯東緣%華北%山西臨縣
자금산%화산궤구%악이다사동연%화북%산서림현
Zijinshan%volcanic structure%eastern margin of the Ordos Basin%North China Block%Lixian Shanxi Province
目的 通过分析紫金山碱性火山机构岩体的岩相学及岩石矿物学特征来研究其岩浆的演化关系.方法 在野外工作的基础上,进行室内显微镜观察分析.结果 紫金山碱性杂岩体是华北地台西部、鄂尔多斯地块东缘,活动期在早白垩纪的一个点式火山机构.岩相学上主要表现为由深成相岩瘤或包体、超浅成相、火山颈相和少量熔岩组成.岩性上主要发育碱性系列和偏碱性系列两个系列岩石类型.碱性系列与偏碱性系列展现出不同的矿物组合.结论 紫金山碱性杂岩体所有岩石类型原始岩浆可能来自两个旋回性质不同地幔条件的部分熔融,派生出8次分期岩浆活动.第一旋回两种性质的原始岩浆在上侵运移过程中有有限混合现象发生.混合的结果使得二长岩中次透辉石中霓石分子的含量增高,显微镜下成绿色,角闪正长岩的正长石斑晶中出现霓石嵌晶,应该为粗安岩的喷出相岩石演化成了粗面质火山岩.碱性系列霞辉正长岩中霓辉石结晶成了次透辉石,使得形成岩石的碱度下降.第二旋回原始岩浆上行过程中有霓霞钛辉岩、正霞正长岩、白霞正长岩的分离结晶作用发生.
目的 通過分析紫金山堿性火山機構巖體的巖相學及巖石礦物學特徵來研究其巖漿的縯化關繫.方法 在野外工作的基礎上,進行室內顯微鏡觀察分析.結果 紫金山堿性雜巖體是華北地檯西部、鄂爾多斯地塊東緣,活動期在早白堊紀的一箇點式火山機構.巖相學上主要錶現為由深成相巖瘤或包體、超淺成相、火山頸相和少量鎔巖組成.巖性上主要髮育堿性繫列和偏堿性繫列兩箇繫列巖石類型.堿性繫列與偏堿性繫列展現齣不同的礦物組閤.結論 紫金山堿性雜巖體所有巖石類型原始巖漿可能來自兩箇鏇迴性質不同地幔條件的部分鎔融,派生齣8次分期巖漿活動.第一鏇迴兩種性質的原始巖漿在上侵運移過程中有有限混閤現象髮生.混閤的結果使得二長巖中次透輝石中霓石分子的含量增高,顯微鏡下成綠色,角閃正長巖的正長石斑晶中齣現霓石嵌晶,應該為粗安巖的噴齣相巖石縯化成瞭粗麵質火山巖.堿性繫列霞輝正長巖中霓輝石結晶成瞭次透輝石,使得形成巖石的堿度下降.第二鏇迴原始巖漿上行過程中有霓霞鈦輝巖、正霞正長巖、白霞正長巖的分離結晶作用髮生.
목적 통과분석자금산감성화산궤구암체적암상학급암석광물학특정래연구기암장적연화관계.방법 재야외공작적기출상,진행실내현미경관찰분석.결과 자금산감성잡암체시화북지태서부、악이다사지괴동연,활동기재조백성기적일개점식화산궤구.암상학상주요표현위유심성상암류혹포체、초천성상、화산경상화소량용암조성.암성상주요발육감성계렬화편감성계렬량개계렬암석류형.감성계렬여편감성계렬전현출불동적광물조합.결론 자금산감성잡암체소유암석류형원시암장가능래자량개선회성질불동지만조건적부분용융,파생출8차분기암장활동.제일선회량충성질적원시암장재상침운이과정중유유한혼합현상발생.혼합적결과사득이장암중차투휘석중예석분자적함량증고,현미경하성록색,각섬정장암적정장석반정중출현예석감정,응해위조안암적분출상암석연화성료조면질화산암.감성계렬하휘정장암중예휘석결정성료차투휘석,사득형성암석적감도하강.제이선회원시암장상행과정중유예하태휘암、정하정장암、백하정장암적분리결정작용발생.
Aim Based on field geology, petrography and previous study on the Zijinshan alkaline complex to propose that the Cretaceous Zijinshan alkaline complex occurred in the eastem margin of the Ordos basin. Methods The alkaline complex was mainly consisted of plutonic facies typhoon or enclaves, hypabyssal facies (batholith , circular and radiant dykes around the collapse volcanic crater) , lava neck facies and minor lavas (flood and eruptive facies) , and it mainly contains alkaline and meta-alkaline series, the alkaline rocks are consisted of leucite + caliofilite + iiwaante + alkaline feldspar, the corresponding dykes are consisted by aegirine + hornblende + kalifeldspath +matrix or kalifeldspath + matrix. The meta alkaline rocks are mainly consisted of plagioclase + homblende + baicalite + biotite + orthoclase + quartz or nepheline + baicalite + acmite + orthoclase + homblende + biotite, the corresponding dykes are composed of homblende + plagioclase + orthoclase + matrix or orthoclase + matrix. Results Then it can be inferred that the parental magma of the Zijinshan alkaline may be derived from two different mantle source and can be divided into eight phase volcanic activity. The alkaline magma may be derived from partial melting of CO_2-dearing therzolite. The two types of magmas from the first circle produce limited magma mixing during their ascent. Conclusion The magmas from the second circle experience fractional crystallization of sussexite +ju-vite. Magma mixing elevated the aegirine molecule in the baicalite. Aegirine inclusion in the orthoclase crystals in-dicate the syenite evolved into trachydacite. Acmite evolved into baicalite and decreased the alkaline content in themagma. The Si, Al contents is significandy affected by fraction crystallization of the alkaline magma.
