中文摘要：

拉萨地块南木林盆地北缘的林子宗群火山岩地层侵位有大量的花岗斑岩岩株和岩脉，空间分布上与南北向正断层的次级断裂相一致。本次研究对南木林盆地北缘的花岗斑岩进行了系统的元素地球化学，LA-MC-ICP-MS锆石U-Pb年代学和Lu-Hf同位素测试。数据结果表明：花岗斑岩具有高硅（68.31%- 71.34%）、高钾（4.52%-4.96%）、高（La/Yb）N（21.59-36.81）、Sr/Y （Sr/Y=15.59 -38.10）等特征，富集大离子亲石元素（LILE），亏损高场强元素（HFSE）；花岗斑岩LA-MC-ICP-MS锆石U-Pb年龄为12-2±0-1Ma，εHf（t）值为-0.6-＋4.0。拉萨地块南木林盆地北缘花岗斑岩岩石学、地球化学特征显示其为新生下地壳部分熔融产物，且源区残留了石榴子石、金红石、角闪石，无斜长石残留，在岩浆上侵过程中，发生了碱性长石的分离结晶作用。花岗斑岩侵位于中新世，与区内南北向裂谷发育时代一致，成分上类似于拉萨地块南部同时期发育的高锶低钇斑岩、钾质岩，同为印度—欧亚大陆碰撞后东西向伸展背景产物。

英文摘要：

There are plenty of granite porphyry stocks and dikes, spatially coincide with the secondary faults associated with the NS-striking normal faults, intruded into the Linzizong volcanic suits located in the northern margin of the Nanmuling basin, Lhasa block. This paper carried out detailed field investigation, zircon LA -ICP-MS U-Pb dating, Lu Hf isotope and element geochemical research for the granite porphyry. The results show that the granite porphyry are high silicon alkaline series, with SiO2= 68.31 - 71.34 %, K2O = 4.52 - 4.96 %, K/Na = 1.53 - 1.9, and Al index （A/CNK） = 0.98 - 1.23. The granite porphyry is characterized by high LILE and low HFSE contents, in addition, it has high （La/Yb）N（21.59 - 36.81） and Sr/Y （Sr/Y = 15.59 - 38.10） values. Zircon LA -ICP -MS U -Pb age of the granite porphyry is 12.23 ± 0.12 Ma and εHf（t） values is -0.6 - ＋4.0. Petrological and geochemical characteristics indicate the granite porphyry was originated from the partial melting of juvenile lower crust, and garnet — rutile — hornblende remains in source area, with the fractional crystallization of alkali feldspar during the invasion. The granite porphyry formed in Miocene, consistent with the deveopment of North — South striking ridge, and its composition similar to high strontium low yttrium porphyry and the potassic rocks in the southern part of the Lhasa block, which is formed associated with an extension setting during the collision of India - Eurasia.