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四川盐源西范坪斑岩铜矿处于扬子地块西缘,靠近盐源-丽江坳陷带与甘孜-理塘缝合带的结合部位,该矿区侵入岩体主要为石英二长斑岩组成。西范坪铜矿石英二长斑岩LA-ICP-MS锆石U-Pb年龄为(100.8±0.7)Ma(MSWD=0.2),表明了斑岩侵位时代为早白垩世。石英二长斑岩富集大离子亲石元素(Rb、Ba、K),亏损高场强元素(Nb、Ta、Ti、P),LREE富集、HREE亏损,为高钾准铝质花岗岩。w(Si O2)为64.06%~65.24%,具有高w(Al_2O3)(15.58%~16.55%)、w(Sr)(719×10~(-6)~1221×10~(-6))及Sr/Y比值(49.2~82.5),低w(MgO)(1.30%~1.63%)、w(Yb)(1.08×10~(-6)~1.55×10~(-6))及w(Y)(13.7×10~(-6)~14.8×10~(-6)),Eu异常(0.83~0.90)不明显,轻重稀土分异明显((La/Yb)N=29.94~52.14),具有埃达克岩特征。西范坪埃达克岩富钾贫钠(K_2O/Na_2O=0.78~2.44),低Cr、Ni,高Th、Th/U以及相对低的Sr/Y等特征,表明其为加厚下地壳部分熔融形成。西范坪早白垩世(100.8Ma)地壳增厚作用可能受控于甘孜-理塘洋闭合后的造山运动,该斑岩体为印支期褶皱造山后(200 Ma),喜马拉雅期碰撞造山之前(65 Ma),陆内由挤压向伸展转换期岩浆作用的产物。
The Xifanping porphyry copper deposit of Yanyuan in Sichuan Province is located at the western margin of the Yangtze block, close to the junction of the Yanyuan-Lijiang Depression belt and the Garze-Litang suture zone. The intrusive rocks in this mine area are mainly composed of quartz monzogranite. LA-ICP-MS zircon U-Pb ages of (100.8 ± 0.7) Ma (MSWD = 0.2) in quartz porphyrite from Xifanping copper deposit indicate that the porphyry emplacement age was Early Cretaceous. The quartz monzonitic porphyry is enriched in large ion lithophile elements (Rb, Ba, K), depleted high field strength elements (Nb, Ta, Ti, P), enriched in LREE and depleted in HREE. (Si 2 O 4) is 64.06% ~ 65.24%, with the contents of high w (15.58% ~ 16.55%) and w (Sr) of 719 × 10 -6 1221 × 10 -6 The ratios of Sr / Y (49.2-82.5), low w (1.30% -1.63%), w (Yb) 1.08 × 10-6 ~ 1.55 × 10-6 and w ) (13.7 × 10 -6 ~ 14.8 × 10 -6), the anomalies of Eu (0.83-0.90) are not obvious, and the variation of light and heavy rare earths is obvious ((La / Yb) N = 29.94-52.14) Adakite Features. The characteristics of rich potassium-poor sodium (K2O / Na2O = 0.78 ~ 2.44), low Cr, Ni, high Th, Th / U and relatively low Sr / Y in the Xiantanping adakite indicate that it is partly melted form. The crustal thickening of the Early Cretaceous (100.8Ma) in Xifanping may be controlled by the orogeny after the closure of the Garzê-Litang Ocean. This porphyry was formed after the Indosinian fold orogeny (200 Ma). Before the Himalayan collision orogeny (65 Ma), the product of magmatic action in the transitional period from crushing to extension.