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本文报道了鲁西早白垩世高镁闪长岩中异剥橄榄岩捕虏体的岩相学与矿物化学资料,以便揭示异剥橄榄岩的成因和岩石圈地幔的深部过程.岩相学研究表明,异剥橄榄岩捕虏体呈浑圆状产于高镁闪长质侵入体中,大小介于3cm×4cm×5cm～3cm×2cm×1cm,并且橄榄石呈残留孤岛状存在于单斜辉石中.矿物化学研究表明,橄榄石的镁橄榄石分子(Fo)介于89～91,Ni=1414～3629ppm,类似于新生代幔源橄榄岩捕虏体中橄榄石的成分,但略低于早白垩世方辉橄榄岩中橄榄石的成分.橄榄石的δ18O值介于(6.03‰±0.33‰)～(6.82‰±0.35‰)(平均值为(6.5‰±0.4‰)),高于典型幔源橄榄岩中橄榄石的δ18O组成(5.2‰±0.3‰).与晚白垩世和新生代玄武岩中地幔橄榄岩捕虏体里的单斜辉石相比,异剥橄榄岩捕掳体中单斜辉石的Na2O,TiO2和Al2O3含量相对偏低,而CaO含量、Mg#值(91.2～94.1)和Ti/Eu比值(Ti/Eu=2082～2845)明显偏高,但与早白垩世高镁闪长岩中方辉橄榄岩里的单斜辉石成分类似单斜辉石以较低的稀土元素(REE)丰度、富集轻稀土元素(LREE)的配分型式和强烈亏损高场强元素(如Nb,Ta,Zr和Hf)为特点.此外,异剥橄榄岩的87Sr/86Sr,143Nd/144Nd和187Os/188Os(125Ma)比值分别变化于0.70596～0.70737,0.512181～0.512416和0.12661～0.57650.上述特征表明异剥橄榄岩为地幔橄榄岩受再循环陆壳物质熔体改造所成.
This paper reports the petrographic and mineralogical data of the xenoliths from the Early Cretaceous high-magnesium diorites in Luxi, in order to reveal the genesis of the de-xenotrophs and the deep processes of the lithospheric mantle. The results show that the xenoliths of the dedipped peridotite are rounded in the form of high-magnesium dioritic intrusions ranging in size from 3 cm × 4 cm × 5 cm to 3 cm × 2 cm × 1 cm and olivine remains as isolated islands in monoclinic Shi Zhong. Mineral chemistry studies have shown that olivine has a forsterite (Fo) range from 89 to 91 and Ni = 1414 to 3629 ppm, similar to Olivine in the Cenozoic mantle-derived peridotite xenolith but slightly lower The composition of olivine in olivic rocks of Early Cretaceous shows that the δ18O value of olivine ranged from (6.03 ‰ ± 0.33 ‰) to (6.82 ‰ ± 0.35 ‰) with an average of (6.5 ‰ ± 0.4 ‰) The δ18O content of olivine in typical mantle source peridotites (5.2 ‰ ± 0.3 ‰). Compared with the clinopyroxenite in the mantle peridotite xenoliths of the Late Cretaceous and Cenozoic basalts, the dextral peridotite captive The contents of Na2O, TiO2 and Al2O3 in the clinopyroxene are relatively low, while the contents of CaO, Mg # (91.2 ~ 94.1) and Ti / Eu ratio (Ti / Eu = 2082 ~ 2845) Similar to the clinopyroxene clinopyroxenes in the Hcls from the Early Cretaceous, the clinopyroxene clinopyroxenes are enriched in the light REE abundance pattern and strongly enriched in the LREE patterns Depleted high field strength elements such as Nb, Ta, Zr and Hf, and the ratios of 87Sr / 86Sr, 143Nd / 144Nd and 187Os / 188Os (125Ma) in the dedotalization peridotites varied from 0.70596 to 0.70737 and from 0.512181 to 0.512416, respectively And 0.12661 ~ 0.57650.The above characteristics show that the detritus-peridotite mantle peridotite is reformed by recycled continental crust material melt.