冀南邯邢地区固镇闪长岩中含橄榄石的闪长质捕虏体的成因矿物学研究  

Genetic mineralogical study of olivine-bearing diorite xenoliths in Guzhen diorite,Handan-Xingtai area,Southern Hebei Province

作　　者：凌诗梦 张聚全 卢静 秦超 吴晓贺 张乐民 LING Shimeng;ZHANG Juquan;LU Jing;QIN Chao;WU Xiaohe;ZHANG Lemin(Hebei Key Laboratory of Strategic Critical Mineral Resources,Hebei GEO University,Shijiazhuang Hebei 050031,China;College of Earth Science,Hebei GEO University,Shijiazhuang Hebei 050031,China)

机构地区：[1]河北省战略性关键矿产资源重点实验室河北地质大学,河北石家庄050031 [2]河北地质大学地球科学学院,河北石家庄050031

出　　处：《矿物学报》2024年第3期383-398,共16页Acta Mineralogica Sinica

基　　金：河北省自然科学基金资助项目(编号:D2021403028)。

摘　　要：邯邢地区中生代侵入岩包含的地幔捕虏体、捕虏晶是来自岩石圈地幔的直接实物证据。该区域所在的华北克拉通中部于中生代发生岩石圈地幔减薄,该事件的主导机制、影响程度和具体过程至今尚未达成共识。本次研究在邯邢地区固镇岩体的闪长质包体中发现橄榄石、辉石等捕虏晶,是研究华北克拉通破坏的重要研究对象。通过对包体中的不同矿物进行成因矿物学研究,讨论其成因及演化,对华北克拉通中生代岩石圈减薄机制进行约束。研究主要取得了以下几点认识:样品中橄榄石的化学成分特征(w(CaO)为0.03%~0.07%,w(Al2O3)为0~0.03%,w(MnO)为0.30%~0.46%)及其与寄主岩浆的不平衡均表明该橄榄石为地幔橄榄岩的解体矿物(捕虏晶),单斜辉石与岩浆平衡,属于早期岩浆的堆晶矿物,并在岩浆体系中发生再循环;橄榄石的Fo值低异常(75%~80%)以及单斜辉石的成分环带(核部相对富镁,边部相对富铁)表明矿物-岩浆反应的存在及其对原始岩浆的影响;角闪石和黑云母富镁,二者均属壳幔混源成因,暗示壳幔相互作用的存在;矿物-岩浆的Fe-Mg交换反应在岩浆早期的广泛存在为该地高镁闪长岩的成因以及拆沉作用的存在提供了佐证。The mantle xenoliths and xenocrysts contained in the Mesozoic intrusive rocks are the direct physical evidence from the lithospheric mantle.The lithospheric mantle thinning occurred in the center of the North China Craton,where this region is located,during the Mesozoic era.The dominant mechanism,effect degree and specific process of this event have not been reached consensus yet.In this study,olivine,pyroxene and other xenocrysts were found in the diorite xenoliths of Guzhen intrusions in Handan-Xingtai area,which are important research objects for the study of the destruction of the North China craton.Through genetic mineralogical study of different minerals in the xenoliths,their genesis and evolution process were discussed,and the thinning mechanism of Mesozoic lithosphere in North China Craton was constrained.The following conclusions are obtained:the chemical composition characteristics of olivine in the sample(w(CaO)=0.03%–0.07%,w(Al2O3)=0–0.03%,w(MnO)=0.30%–0.46%)and the imbalance with the host magma indicate that the olivine are the disintegrated products of mantle peridotite(xenocrysts).And the clinopyroxene are in equilibrium with the magma,belonging to the cumulates of early magma,which is recycled in the magmatic system;The low Fo value anomaly of olivine(Fo=75%–80%)and the compositional zone of clinopyroxene(relatively rich in magnesium in the core and iron in the rim)indicate the existence of mineral-magmatic reaction and its influence on the original magma.Amphibole and biotite are rich in magnesium,both of which belong to crust-mantle mixed origin,implying the existence of crust-mantle interaction.The extensive occurrence of mineral-magmatic Fe-Mg exchange reaction in the early magmatic period provides evidence for the origin of high magnesium diorite and the existence of delamination in this area.

关 键 词：橄榄石 捕虏晶 单斜辉石 邯邢地区 

分 类 号：P571[天文地球—矿物学] P574.2[天文地球—地质学] P575.1