摘要
杂岩体呈由西向东展布的北北东向的三个岩带,并显示有规律的演化趋势。SiO2含量52.26—62.95,钙碱性C.A=57.6。AFM图上显示Fe.Mg降低而碱质增高的演化趋势。∑REE从126.2到185.1(ppm)呈依次渐增趋势。稀土元素配分型式呈右倾斜的轻稀土富集型,(La/Yb)N=11.27,δEu=1.07—1.15。δ18O在8.2—8.8之间数据迭置。岩浆中水的δD为-45和-68,δ18O为7.7和9.2,具原始岩浆水的特征。岩石具低铷高锶特征,初始锶比值为0.7053和0.7064。岩体中含有众多的岩石包体,除浅源和结晶基底的围岩捕虏体外,还显示保留有幔源的难熔残余超镁铁岩包体。杂岩体的岩石学与地球化学特征反映了岩浆物质的同源性以及揭示了可能起源于莫霍面附近的深源信息。
There are three NNE trend rock belts from west to east and their intrusive ages, intrusive position as well as lithologic characters appeared as of systematic evolution. There are many xenolithes in the initial petrographic facies, such as wall rock, deep seated crystal base and ultramafic rock xenolith from mantle, These imply the possible occurrence of the difficult melting residue from deeper source in the Complex.
The C.A. index of the Complex is 57.6 and AFM diagram indicates thet Fe, Mg decreased and alkaline increased with time. The chondrite-normalized REE pattern of rocks is richin LREE, (La/Yb)_N=11.27, δ Eu=1.07-1.15. δ^(18)O values of whole rock range from 8.2 to 8.8. δD of magmatic water is from -45 to -68 and δ^(18)O of magmatic water ranges from 7.7 to 9.2, reflecting original magmatic water's characters. The rocks show low Rb end high Sr values and initial strotium ratio ranges from 0.7053 to 0.7064.
The geochemical characters of the Complex and their consistency imply an information that the magma meterials may be derived from uniform deeper source. It is possible that the source is situated in the lower level of lower-crust according to the residue of ultramafic xenolith from the mantle-source. As a result of activation the Taihang fault-block in Mesozoic in North China Plate, the slabs of the mantle diapir penetrated and underwent partly melting. By batch melting and progressive magma intrusion, the Hun Xing Complex was composed of the evolutional sequence from basic, intermediate to alkaline in order of age.
出处
《岩石矿物学杂志》
CAS
CSCD
1990年第3期203-212,共10页
Acta Petrologica et Mineralogica
基金
国家自然科学基金
关键词
侵入岩
杂岩
岩石学
地球化学
intermediate-basic intrusive complex
petrographical and geochemical characteristics
deeper source
