矿物岩石地球化学通报
礦物巖石地毬化學通報
광물암석지구화학통보
BULLETIN OF MINERALOGY PETROLOGY AND GEOCHEMISTRY
2015年
3期
601-618
,共18页
元素地球化学%放射成因同位素%超镁铁质岩%苏鲁造山带
元素地毬化學%放射成因同位素%超鎂鐵質巖%囌魯造山帶
원소지구화학%방사성인동위소%초미철질암%소로조산대
element geochemistry%radiogenic isotopes%mafic-ultramafic rock%Sulu metamorphic zone
苏鲁造山带中胡家林超镁铁质岩地块主要由两部分组成：南部滑石山以蛇纹岩和蛇纹石化橄榄岩为主，夹薄层状石榴橄辉岩-（石榴）单斜辉石岩；北部胡家林主要由（石榴）单斜辉石岩组成，夹厚层状蛇纹岩。蛇纹岩-蛇纹石化橄榄岩低Al2 O3、低 CaO 和高 MgO，REE 含量低，但 LREE 稍富集。石榴橄辉岩和（石榴）单斜辉石岩低 MgO 和 CaO，高 REE 含量高，其稀土配分曲线均表现出单斜辉石单矿物的配分特征。这些超镁铁岩块中不同岩石的微量元素均具有 Pb 的正异常，弱的 Nb、Ta 的负异常，显示地壳流体交代信息。Nd、Sr、Pb 同位素特征显示存在亏损地幔与地壳之间的混合作用。亲石元素含量最低的蛇纹石化石榴橄辉岩的 Sr、Nd、Pb 同位素组成受交代流体控制明显，而石榴橄辉岩和（石榴）单斜辉石岩不明显。胡家林和滑石山超镁铁岩中所含的交代地壳成分不同，胡家林样品受到含水熔体和富水流体的双重交代，滑石山样品主要受富水流体的交代。
囌魯造山帶中鬍傢林超鎂鐵質巖地塊主要由兩部分組成：南部滑石山以蛇紋巖和蛇紋石化橄欖巖為主，夾薄層狀石榴橄輝巖-（石榴）單斜輝石巖；北部鬍傢林主要由（石榴）單斜輝石巖組成，夾厚層狀蛇紋巖。蛇紋巖-蛇紋石化橄欖巖低Al2 O3、低 CaO 和高 MgO，REE 含量低，但 LREE 稍富集。石榴橄輝巖和（石榴）單斜輝石巖低 MgO 和 CaO，高 REE 含量高，其稀土配分麯線均錶現齣單斜輝石單礦物的配分特徵。這些超鎂鐵巖塊中不同巖石的微量元素均具有 Pb 的正異常，弱的 Nb、Ta 的負異常，顯示地殼流體交代信息。Nd、Sr、Pb 同位素特徵顯示存在虧損地幔與地殼之間的混閤作用。親石元素含量最低的蛇紋石化石榴橄輝巖的 Sr、Nd、Pb 同位素組成受交代流體控製明顯，而石榴橄輝巖和（石榴）單斜輝石巖不明顯。鬍傢林和滑石山超鎂鐵巖中所含的交代地殼成分不同，鬍傢林樣品受到含水鎔體和富水流體的雙重交代，滑石山樣品主要受富水流體的交代。
소로조산대중호가림초미철질암지괴주요유량부분조성：남부활석산이사문암화사문석화감람암위주，협박층상석류감휘암-（석류）단사휘석암；북부호가림주요유（석류）단사휘석암조성，협후층상사문암。사문암-사문석화감람암저Al2 O3、저 CaO 화고 MgO，REE 함량저，단 LREE 초부집。석류감휘암화（석류）단사휘석암저 MgO 화 CaO，고 REE 함량고，기희토배분곡선균표현출단사휘석단광물적배분특정。저사초미철암괴중불동암석적미량원소균구유 Pb 적정이상，약적 Nb、Ta 적부이상，현시지각류체교대신식。Nd、Sr、Pb 동위소특정현시존재우손지만여지각지간적혼합작용。친석원소함량최저적사문석화석류감휘암적 Sr、Nd、Pb 동위소조성수교대류체공제명현，이석류감휘암화（석류）단사휘석암불명현。호가림화활석산초미철암중소함적교대지각성분불동，호가림양품수도함수용체화부수류체적쌍중교대，활석산양품주요수부수류체적교대。
The ultramafic body at Hujialin consists of two parts.The southern part,which is the Huashishan body,con-sists mainly of serpentinite and serpentinized peridotite with thin layers of garnet olivine pyroxenite and (garnet)clinopy-roxenite.The northern part consists mainly of clinopyroxenite with thick layer of serpentinite.Serpentinite and serpentinized peridotite are low in Al2 O 3 and CaO and high in MgO.These rocks are low in REE,but slightly enrich in LREE.The garnet olivine pyroxenite and (garnet)clinopyroxenite are low in MgO and high in CaO and total REE con-tents.Primitive mantle-normalized trace element patterns for all types of mafic-ultramafic rocks show positive Pb anomaly and weak negative Nb and Ta anomalies,suggesting metasomatism of crustally derived fluid /melt.The Sr,Nd and Pb iso-topic compositions of these ultramafic rocks can be explained by mixing between the depleted mantle and the crust at 216,Ma.The serpentinized garnet olivine pyroxenite exhibits the lowest concentrations of lithophile elements,suggesting significant contributions from the metasomatic fluid /melt.The garnet olivine pyroxenite and (garnet)clinopyroxenite were metasomatised by hydrous melt.Therefore,the ultramafic rocks were metasomatised by different compositions of crustal material.
