| 章邦桐,吴俊奇,凌洪飞,陈培荣.南岭寨背和陂头花岗岩基属印支期侵位的岩浆动力学证据及构造意义[J].地质找矿论丛,2011,26(2):119-130,161 |
| 南岭寨背和陂头花岗岩基属印支期侵位的岩浆动力学证据及构造意义 |
| Magma-dynamic evidence for Indo-sinian cycle emplacement of the Zhaibei and Pitou granite batholith of Nanling range in south China and the tectonic implication |
| 投稿时间：2010-02-09 |
| DOI：10.6053/j.issn.1001-1412.2011.2. 001 |
| 中文关键词: 寨背和陂头花岗岩基 侵位年龄 侵位-结晶时差 印支造山运动 岩浆动力学证据 |
| 英文关键词:Zhaibei and Pitou Granite Batholith emplacement age emplacement-crystallization time difference Indo-Sinian Orogeny magma-dynamic evidence |
| 基金项目:中国核工业地质局“十一五”基础科研项目(编号YK08);内生金属矿床成矿机制研究国家重点实验室研究项目(编号2008-I-04);教育部科学研究重大项目(306007)资助 |
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| 中文摘要: |
| 文章通过对南岭东段寨背和陂头岩基地质-岩石地球化学特征研究,判明它们的侵位深度(7.5 km)、围岩温度(250℃)及岩浆初始温度(950℃),建立起寨背—陂头岩基的数学计算模型,并计算得出:寨背和陂头花岗岩熔体侵位后,其初始温度降低至结晶温度所需的时间(Δtcol)分别为4.04 Ma(寨背岩基)和3.97 Ma(陂头岩基);由于结晶潜热释放而使结晶过程延长的时间(ΔtL)为3.02 Ma,2.96 Ma;由于寨背和陂头花岗岩基放射性元素的质量分数高于世界平均花岗岩放射性元素含量(w(U)=5×10-6,w(Th)=20×10-6,w(K2O)=2.66%),寨背和陂头花岗岩浆侵位后产生的放射成因热使结晶过程延长的时间(ΔtA)分别为14.3 Ma和5.16 Ma,远长于按世界平均花岗岩放射性元素质量分数计算得出的ΔtA(3.1 Ma和2.9 Ma)。寨背和陂头花岗岩基的侵位-结晶时差(ΔtECTD)为21.4 Ma和12.1 Ma,结合同位素年龄值(锆石U-Pb年龄及全岩Rb-Sr等时线年龄的平均值为173.8 Ma(寨背)和182.3 Ma(陂头)),通过反演计算得出寨背和陂头花岗岩基侵位年龄值(tE)分别为195.2 Ma和194.4 Ma,从而为寨背和陂头花岗岩基属于印支期侵位提供了重要的岩浆动力学佐证。 |
| 英文摘要: |
| The geological-geochemical features of the Zhaibei and Pitou Granite Batholith reveal that the emplacement depth is 7.5km and temperature of the enclosing rock 250℃,the initial temperature of the magma 950℃.Based on the data mathematic model is established calculating that after emplacement the cooling period from the initial magma temperature to the crystallization is 4.04 Ma at Zhaibei and 3.97 Ma at Pitou;the prolongation period(ΔtL) caused by latent heat release 3.02 Ma and 2.96 Ma respectively.Since the radioactive element content of the Batholith,U=10.32×10-6,Th=46.9×10-6t,K2O=5.38%(Zhaibei);U=6.28×10-6t,Th=29.7×10-6t,K2O=5.37%(Pitou) are as high as 2 times of those of the global granite average,U=5×10-6t,Th=20×10-6t,K2O=2.66%,the prolongation period(ΔtA) caused by radiogenic heat are 14.3 Ma and 5.16Ma,which are much longer than the global averageΔtA,3.1 Ma and 2.9Ma.Therefore,the time elapsed from emplacement to the end of crystallization(ΔtECTD) should be the sum ofΔtcol,ΔtL and ΔtA,21.4 Ma and 12.1 Ma.In combination with isotopic ages of 173.8 Ma and 182.3 Ma which represent the crystallization age,the emplacement ages at Zhaibei and Pitou are estimated to be 195.2 Ma and 194.4 Ma.These suggest that the emplacement of the Zhaibei and Pitou granite Batholith took place in the Indo-Sinian Period. |
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