Geochronology of the Hannan intrusive complex to adjoin the Qinling orogen and its rapid cooling reason  

作　　者：ZHANG Zongqing ZHANG Guowei TANG Suohan ZHANG Qiaoda WANG Jinhui 

机构地区：[1]Institute of Geology,Chinese Academy of Geosciences,Beijing 100037,China [2]Department of Geology,Northwest University,Xi’an 710069,China

出　　处：《Chinese Science Bulletin》2001年第8期685-689,共5页

基　　金：the NationalNatural Science Foundation of China (Grant Nos. 49732080 and 49773182).

摘　　要：The geochronological works for the Hannan intrusive complex, cosisting of the gabbro-quartz dio-rite-plagiogranite bodies, in the north border of the Yangtze craton block, adjoining the Qinling orogen, are reported, because its age and genesis are of great importance to research of the tectonic evalutional history for the Qinling orogen and of the rifted processes for the Late Proterozoic supercontinent Rodinia. A good isochron of t=(837±26) Ma (2σ), corresponding to INd=0.51165±2(2σ), εNd(t)=+1.9, MSWD1.02, was difined by the Nd isotopic analytical results for the 21 whole-rock samples from the varied lithological complex bodies, but for the Rb-Sr isotopic aralytical data there is no isochron. The 40Ar/39Ar plateau age of the biotite, sorted from plagiogranites, is (796±20) Ma(2σ), and yet for the Rb-Sr isotopic data of the plagiogranite whole-rock samples (WR) and the sorted biotite (Bio), plagioclase (Plag) and apatite (Apt) mineral samples from the plagiogranitewhole-rock samples, anThe geochronological works for the Hannan intrusive complex, cosisting of the gabbro-quartz diorite-plagiogranite bodies, in the north border of the Yangtze craton block, adjoining the Qinling orogen, are reported, because its age and genesis are of great importance to research of the tectonic evalutional history for the Qinling orogen and of the rifted processes for the Late Proterozoic supercontinent Rodinia. A good isochron of t=(837±26) Ma (2σ), corresponding to INd=0.51165±2(2σ), εNd(t)=+1.9, MSWD1.02, was difined by the Nd isotopic analytical results for the 21 whole-rock samples from the varied lithological complex bodies, but for the Rb-Sr isotopic aralytical data there is no isochron. The40Ar/39Ar plateau age of the biotite, sorted from plagiogranites, is (796±20) Ma(2σ), and yet for the Rb-Sr isotopic data of the plagiogranite whole-rock samples (WR) and the sorted biotite (Bio), plagioclase (Plag) and apatite (Apt) mineral samples from the plagiogranite whole-rock samples, an isochron of t=(824.8±3.8) Ma (2σ) with ISr=0.70393±14(2σ), MSWD2.44 is given. The U-Pb isotopic results for the single zircon, sorted from plagiogranite samples, yielded an upper and a lower intercept ages of ～876 Ma and ～273 Ma. The Nd isotope data of complex indicate that it is probably the products of crystallization differentiation from the magma with εNd> 0 when the rapid uplift in 837–800 Ma took place in the northern border of the Yangtze craton block.

关 键 词：ISOTOPIC GEOCHRONOLOGY Hannan INTRUSIVE complex QINLING OROGEN China. 

分 类 号：P533[天文地球—古生物学与地层学]