At the Black Mountain porphyry Cu-Au deposit in the Baguio district, Northern Luzon (Philippines), pre- and synmineralized rocks preserve magmatic and hydrothermal minerals (e.g., plagioclase, amphibole, titanite, and epidote) spanning the complete paragenesis of the deposit. Strontium isotope values in early crystallized plagioclase phenocrysts from all felsic porphyries can be divided into two types. The type-I plagioclase crystals show relatively homogeneous Sr isotope values (0.7035-0.7038, 1σ <0.0001), indicating crystallization from a relatively stable and long-lived felsic magma chamber. The type-II plagioclase grains have a wider range of Sr isotope compositions (0.7032-0.7039, 1σ <0.0001), indicating mafic and/or felsic magma recharge. In magmatic titanite, Nb/Ta values are higher than those in the whole rock, while Zr/Hf and Y/Ho values are lower. In hydrothermal titanite and epidote, the ratios are similar to those in the whole rock. These patterns reflect crystallization effects imposed during the magmatic stage but an absence of differentiation during the hydrothermal stage. The consistent gradual decrease in total rare earth element, Y, Zr, and U contents in both hydrothermal titanite and epidote from early to late stages indicates the effect of hydrothermal fluid evolution with decreasing temperature. The variation of 87Sr/86Sr values in magmatic amphibole, plagioclase, and hydrothermal epidote in felsic and mafic rocks indicates the addition of mafic magma-derived fluid into the felsic magma-derived fluid. One extra source of fluid (probably derived from wall-rock limestone) was required to generate the highly radiogenic 87Sr/86Sr values of some epidote (0.7038-0.7053). Thus, in situ elemental and Sr isotope variation in minerals from different paragenetic stages can be used to interpret formation process and source for both magmas and hydrothermal fluids.

中文翻译：

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菲律宾碧瑶区黑山斑岩矿床岩浆至热液矿物的原位元素和 Sr 同位素特征

在北吕宋（菲律宾）碧瑶区的黑山斑岩铜金矿床，预矿化和同矿化的岩石保存着岩浆和热液矿物（例如斜长石、角闪石、钛铁矿和绿帘石），跨越了整个矿床的共生作用。来自所有长英质斑岩的早期结晶斜长石斑晶中的锶同位素值可分为两种类型。I 型斜长石晶体显示出相对均匀的 Sr 同位素值 (0.7035-0.7038, 1σ <0.0001)，表明结晶来自相对稳定和长寿命的长英质岩浆房。II型斜长石颗粒具有更广泛的Sr同位素组成（0.7032-0.7039，1σ <0.0001），表明镁铁质和/或长英质岩浆补给。岩浆钛铁矿中 Nb/Ta 值高于全岩，而 Zr/Hf 和 Y/Ho 值较低。在热液钛白石和绿帘石中，比例与整个岩石中的比例相似。这些模式反映了在岩浆阶段施加的结晶效应，但在热液阶段没有分异。热液钛白石和绿帘石中稀土元素总量、Y、Zr 和 U 含量从早期到晚期持续逐渐下降，表明热液流体演化随温度降低的影响。长英质和基性岩中岩浆角闪石、斜长石和热液绿帘石的87Sr/86Sr值的变化表明长英质岩浆衍生流体中加入了镁铁质岩浆衍生流体。需要一种额外的流体源（可能来自围岩石灰岩）来产生某些绿帘石 (0.7038-0.7053) 的高放射成因 87Sr/86Sr 值。因此，不同共生阶段矿物的原位元素和 Sr 同位素变化可用于解释岩浆和热液流体的形成过程和来源。