CAJ | 학술논문

通过青海东昆仑东部沟里地区阿斯哈岩体中寄主闪长岩和暗色微粒包体的岩相学、全岩地球化学研究，确定了岩石成因及其构造属性。阿斯哈岩体中暗色包体广泛分布，包体岩性主要为角闪辉长岩。包体具有岩浆结构，部分包体具有塑性流变特征，包体中可见寄主岩石矿物的捕掳晶和针状磷灰石，表现出岩浆混合的岩相学特征。主岩及暗色包体同属准铝质、高钾钙碱性钾玄岩系列过渡岩石，主量元素在Harker图解及 Al2 O3/K2 O CaO/K2 O和 SiO2/CaO K2 O/CaO的共分母协变图上具良好的线性关系，反映两者成分的变化与岩浆混合作用有关。两者的稀土元素配分模式总体一致，显示二者密切的成因联系。两者都富含大离子亲石元素（Rb、K ），相对亏损高场强元素（Nb、Ta、P、Ti ）。暗色包体具有贫硅（w（SiO2）＝50．70％～53．88％）和富镁、铁、钙的地球化学特征，其 Mg＃值较高（Mg＃＝0．52～0．59），暗示其来源于俯冲带流体交代地幔楔的部分熔融。主岩的 Rb/Sr值为0．22～0．27，接近地壳平均值，Nb/Ta值为14．5～15．2，介于地幔平均值与地壳平均值之间，表明寄主岩石岩浆具有壳源岩浆的性质并经历了幔源岩浆的混合作用。结合区域构造演化及构造判别，认为阿斯哈岩体形成于安第斯型活动大陆边缘的构造环境。早三叠世，阿尼玛卿洋向北俯冲，俯冲带流体交代地幔楔，导致其部分熔融形成基性岩浆，底侵的幔源基性岩浆诱发下地壳部分熔融并与之发生混合形成本区闪长岩，而其中的暗色包体为幔源岩浆混合不彻底的产物。
통과청해동곤륜동부구리지구아사합암체중기주섬장암화암색미립포체적암상학、전암지구화학연구，학정료암석성인급기구조속성。아사합암체중암색포체엄범분포，포체암성주요위각섬휘장암。포체구유암장결구，부분포체구유소성류변특정，포체중가견기주암석광물적포로정화침상린회석，표현출암장혼합적암상학특정。주암급암색포체동속준려질、고갑개감성갑현암계렬과도암석，주량원소재Harker도해급 Al2 O3/K2 O CaO/K2 O화 SiO2/CaO K2 O/CaO적공분모협변도상구량호적선성관계，반영량자성분적변화여암장혼합작용유관。량자적희토원소배분모식총체일치，현시이자밀절적성인련계。량자도부함대리자친석원소（Rb、K ），상대우손고장강원소（Nb、Ta、P、Ti ）。암색포체구유빈규（w（SiO2）＝50．70％～53．88％）화부미、철、개적지구화학특정，기 Mg＃치교고（Mg＃＝0．52～0．59），암시기래원우부충대류체교대지만설적부분용융。주암적 Rb/Sr치위0．22～0．27，접근지각평균치，Nb/Ta치위14．5～15．2，개우지만평균치여지각평균치지간，표명기주암석암장구유각원암장적성질병경력료만원암장적혼합작용。결합구역구조연화급구조판별，인위아사합암체형성우안제사형활동대륙변연적구조배경。조삼첩세，아니마경양향북부충，부충대류체교대지만설，도치기부분용융형성기성암장，저침적만원기성암장유발하지각부분용융병여지발생혼합형성본구섬장암，이기중적암색포체위만원암장혼합불철저적산물。
The authors report petrographical and whole-rock geochemical data of the host diorite and mafic microgranular enclaves(MMEs)within the Asiha diorite pluton at Gouli area in eastern Qinghai East Kunlun,and ascertain their petrogenesis and tectonic setting.The Asiha diorite pluton contains abundant MMEs which are mainly amphibole gabbro.The MMEs display igneous-texture and some of them are characterized by plastic flow deformation.The MMEs have plagioclase,amphibole and quartz xenocrysts and acicular apatite, which belongs to petrographical characteristics of magma mixing. Authors systematically studied petrological and geochemical characteristics of the host rocks and the MMEs,and conclude that both are meta-aluminous,high-K calc-alkaline series-shoshonitic series rocks. The selected major oxides of the MMEs and the host rocks show a linear correlation in Harker diagrams. In addition, Al2 O3/K2 O CaO/K2 O and SiO2/CaO K2 O/CaO identical oxide ratio denominator covariant diagram of the MMEs and their host rocks also show a linear correlation,which indicate their composition change is related to the magma mixing and mingling.Trace elements data show that they are both enriched in large ion lithophile elements (Rb,K)and depleted in high field strength elements (Nb,Ta,P and Ti).The MMEs are characterized by low SiO2 contents (SiO2=50.70% 53.88%), high MgO,Fe2O3 and CaO contents,as well as a higher Mg# value (Mg#=0.52 0.59),which indicates that the primary magma was derived from the partial melting of the mantle wedge.The Rb/Sr ratio of the host rocks varies from 0.22 to 0.27,which is close to but less than average values of the earth crust.The Nb/Ta ratio of the host rocks varies from 14.5 to 15.2,which is between the average values of the crust and mantle,suggesting that the magma of the host rocks is mainly from crust and experienced magma mixing.Combined with regional tectonic evolution and discrimination of tectonic setting,we suggest that the Asiha diorite pluton formed in the Andean-type active continental margin. In Early Triassic,the A’nyemaqen ocean subducted northward,the subduction slab dehydrate led to fluid metasomatism,inducing partial melting of mantle wedge to form the mafic magma.The mafic magma underplated the overlying lower crust,resulting in its partial melting and then mixed with the crustal magma to form the Asiha diorite pluton,while the MMEs are the residually basic part of magma mixing.