| 花岗岩浆侵位与结晶固化时差的研究与构造意义:以南岭骑田岭花岗岩基为例 |
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| 引用本文： | 章邦桐,吴俊奇,凌洪飞,陈培荣.花岗岩浆侵位与结晶固化时差的研究与构造意义:以南岭骑田岭花岗岩基为例[J].高校地质学报,2010,16(1):103-118. |
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| 作者姓名： | 章邦桐 吴俊奇 凌洪飞 陈培荣 |
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| 作者单位： | 内生金属矿床成矿机制研究国家重点实验室(南京大学), 南京大学 地球科学与工程学院， 南京 210093 |
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| 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)的资助成果 |
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| 摘 要： | 通过对南岭中段骑田岭花岗岩基地质-岩石地球化学特征研究,判明了该岩基的侵位深度(5.5km)、围岩温度(196℃)及岩浆初始温度(950℃),建立起骑田岭花岗岩基的数学计算模型,计算得出:骑田岭花岗岩熔体侵位后,其初始温度降低至结晶温度所需的时间(Δtcol)为4.1Ma;由于结晶潜热释放而使结晶过程延长的时间(ΔtL)为2.6Ma;由于骑田岭花岗岩基放射性元素含量(U-15.3×10-6,Th-51.35×10-6,K2O-5.02%)是世界平均花岗岩放射性元素含量(U-5×10-6,Th-20×10-6,K2O-2.66%)的2~3倍,骑田岭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)为35.4Ma,远长于世界平均花岗岩计算的ΔtA(2.93Ma)。因此,骑田岭花岗岩基的岩浆侵位-结晶固化时差(ΔtECTD)为42.1Ma,结合锆石U-Pb年龄值(161Ma),通过反演计算得出骑田岭花岗岩基侵位年龄值(tE)为203.1Ma,从而为骑田岭花岗岩基属于印支期侵位提供了重要的岩浆动力学佐证。
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| 关 键 词： | 骑田岭花岗岩基 侵位年龄 侵位-结晶时差 印支造山运动 岩浆动力学证据 |
| 修稿时间： | 2010-03-20 |
On the Time Elapsed from Magma Emplacement to Crystallization-Solidification of Granites and Its Tectonic Implication: Taking the Qitianling Granite Batholith of Nanling Range in Sourth China as an Example |
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| ZHANG Bang-tong,WU Jun-qi,LING Hong-fei,CHEN Pei-rong.On the Time Elapsed from Magma Emplacement to Crystallization-Solidification of Granites and Its Tectonic Implication: Taking the Qitianling Granite Batholith of Nanling Range in Sourth China as an Example[J].Geological Journal of China Universities,2010,16(1):103-118. |
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| Authors: | ZHANG Bang-tong WU Jun-qi LING Hong-fei CHEN Pei-rong |
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| Institution: | State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China |
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| Abstract: | From the geological-geochemical features of the Qitainling granite batholith, the depth of emplacement (5.5 km).temperature of country rocks (196℃) and initial temperature of granite melt (950℃) during its emplacement are ohtained.With these parameters a mathematic model calculating the emplacement age of the Qitainling granite batholith is established in this paper. Model calculation results suggest that the cooling time (△t_(col)) for the Qitainling granite batholith from its initial temperature to crystallization temperature was 4.1 Ma, and the prolongation time (△t_L) caused by latent heat generated from crystallization was 2.6 Ma. Since the radioactive elements of the Qitainling granite batholith (U, 15.3×10~(-6); Th, 51.35×10~(-6);K_2O. 5.02 %) are as high as 2～3 times of those of the world average granite (U,5×10~(-6); Th, 20×10~(-6); K_2O, 2.66 %), the prolongation time (Δt_A) caused by radiogenic heat from the decay of the radioactive elements was 35.4 Ma , which is much longer than the Δt_A value calculated for the world average granite (2.93 Ma). Therefore, the time elapsed from the magma emplacement to the crystallization-solidification (Δt_(ECTD)), which should be the sum of Δt_(col),Δt_L , and Δt_A, was 42.1 Ma for the Qitainling granite batholith. In combination with zircon U-Pb age of the granite (161 Ma) representing the crystallization age, the emplacement age of the Qitainling granite batholith is estimated to be 203.1 Ma. This suggests that the emplacement of the Qitainling granite magma was in the Indo-Sinian Period. |
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| Keywords: | Qitainling granite batholith emplacement age emplacement-crystallization time difference Indo-Sinian orogeny magma-dynamic evidence |
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