CAJ | 학술논문

在扬子克拉通东南缘的江山-绍兴结合带沿线多处出露新元古代深成杂岩，以往被认为是沿扬子克拉通和华夏地块碰撞缝合带侵入的板内型深成岩类。本文选择其中的浙江金华罗店中酸性深成杂岩进行了系统的岩石学、年代学和地球化学研究，提出它们属TTG岩石组合，包括英云闪长岩-奥长花岗岩-花岗闪长岩组合（T1 T2 G1）和二长花岗岩-花岗岩组合（G2 QM）两类，普遍以明显富集Rb、Ba、K、Pb等大离子亲石元素而强烈亏损Nb、Ta、Ti、P等高场强元素为特征，δCe为弱负异常或无异常，属典型的弧岩浆岩类。T1 T2 G1组合富钠贫钾，ε Nd （t）值＝＋2．6～＋9．4，Mg＃值为41．5～63．1，推断由玄武质俯冲板片脱水部分熔融而成，并受到地幔楔橄榄岩熔体的混染。G2 QM组合与T1 T2 G1组合地球化学特征类似，但又明显富K2 O（2．75％～5．08％）、LILE和LREE，低Mg＃值（27．2～52．31）和ε Nd （t）值（＋1．7～＋2．0），应是T1 T2 G1源区继续部分熔融的产物，可能未受到明显的地幔楔橄榄岩混染。测得花岗闪长岩（G1）锆石 SHRIMP U-Pb 年龄为841±10Ma，奥长花岗岩（T2）锆石 LA-ICP-MS U-Pb年龄为793±13Ma，前人报道之花岗岩（G2）年龄为832±44Ma，结合上述地球化学特征，说明T1 T2 G1和G2 QM组合是由新元古代古华南洋向扬子东南缘持续俯冲形成的。综合区域地质资料及前人研究结果，提出金华罗店与诸暨璜山、绍兴平水等地的深成杂岩共同构成了扬子克拉通东南缘一条长达200km 的青白口纪（930～793Ma）陆缘弧型深成杂岩带，反映迟至793Ma前仍存在强烈的洋壳俯冲，扬子克拉通尚未与华夏地块发生碰撞拼合，且T1 T2 G1-G2 QM组合的出现指示洋壳俯冲正处于早-中期阶段。
재양자극랍통동남연적강산-소흥결합대연선다처출로신원고대심성잡암，이왕피인위시연양자극랍통화화하지괴팽당봉합대침입적판내형심성암류。본문선택기중적절강금화라점중산성심성잡암진행료계통적암석학、년대학화지구화학연구，제출타문속TTG암석조합，포괄영운섬장암-오장화강암-화강섬장암조합（T1 T2 G1）화이장화강암-화강암조합（G2 QM）량류，보편이명현부집Rb、Ba、K、Pb등대리자친석원소이강렬우손Nb、Ta、Ti、P등고장강원소위특정，δCe위약부이상혹무이상，속전형적호암장암류。T1 T2 G1조합부납빈갑，ε Nd （t）치＝＋2．6～＋9．4，Mg＃치위41．5～63．1，추단유현무질부충판편탈수부분용융이성，병수도지만설감람암용체적혼염。G2 QM조합여T1 T2 G1조합지구화학특정유사，단우명현부K2 O（2．75％～5．08％）、LILE화LREE，저Mg＃치（27．2～52．31）화ε Nd （t）치（＋1．7～＋2．0），응시T1 T2 G1원구계속부분용융적산물，가능미수도명현적지만설감람암혼염。측득화강섬장암（G1）고석 SHRIMP U-Pb 년령위841±10Ma，오장화강암（T2）고석 LA-ICP-MS U-Pb년령위793±13Ma，전인보도지화강암（G2）년령위832±44Ma，결합상술지구화학특정，설명T1 T2 G1화G2 QM조합시유신원고대고화남양향양자동남연지속부충형성적。종합구역지질자료급전인연구결과，제출금화라점여제기황산、소흥평수등지적심성잡암공동구성료양자극랍통동남연일조장체200km 적청백구기（930～793Ma）륙연호형심성잡암대，반영지지793Ma전잉존재강렬적양각부충，양자극랍통상미여화하지괴발생팽당병합，차T1 T2 G1-G2 QM조합적출현지시양각부충정처우조-중기계단。
Along the southeastern margin of the Yangtze Carton expose several Neoproterozoic dioritic-granitic plutonic complexes,which were considered as within-plate plutons intruding along the Jiangshan-Shaoxing suture belt between the Yangtze Carton and Cathaysia Block.This paper introduces petrography, chronology and geochemistry of Luodian intermediate-acid plutonic complex in Jinhua,Zhejiang Province, and ascribed as TTG assemblage that including T1 T2 G1 (tonalite-trondhj emite-granodiorite )and G2 QM (granite-quartz monzonite).They display typical geochemical characters of arc magmas,i.e.,weakly negative Ce anomalies and obvious enrichments in LILE such as Rb,Ba,K,Pb,whereas depletion in HFSE such as Nb,Ta,Ti,P.T1T2G1 ssemblages,showing high Na,low K with high Mg# (41. 5~63. 1) andε Nd (t)(+2 .6~+9 .4 ),may be formed by the partial melting of dehydrated subducted basaltic slab and partly assimilated by mantle wedge.G2 QM assemblages,having similar geochemical features to T1 T2 G1 whereas comparatively higher K2 O content (from 2.75 % to 5.08 %),higher LILE and LREE,and lower Mg# value (27.2~52.3)andε Nd(t)(+1.7~+2.0),implicated the subsequent partial melting of the subducted slab but without obvious assimilation of mantle wedge.Their zircon U-Pb ages of granodiorite(G1 ),trondhjemite(T2 )and granite(G2 )are 841 ±10Ma(SHRIMP),793 ±13Ma(LA-ICP-MS)and 832±44Ma,respectively,indicating these T1T2G1 and G2QM rocks were continental margin arc magmatites formed by continuous subduction of Paleo-Nanhua Ocean slab in Neoproterozoic.Combined with regional geologies and previous studies, it is proposed that, Luodian complex in Jinhua and Huangshan complex in Zhuji as well as Pingshui complex in Shaoxing make up a 200km long, Neoproterozoic (930 ~ 793Ma ) continental margin-arc plutonic complex zone.In other words, the southeastern margin of the Yangtze Carton had not collided and amalgamated with the Cathaysia Block at least until 793 Ma,while coexisting of T1 T2 G1-G2 QM rocks predicate an early-middle subduction of oceanic crust.