The 119 Ma Dinkey Dome pluton in the central Sierra Nevada Batholith is a peraluminous granite and contains magmatic garnet and zircon that are complexly zoned with respect to oxygen isotope ratios. Intracrystalline SIMS analysis tests the relative importance of magmatic differentiation processes vs. partial melting of metasedimentary rocks. Whereas δ18O values of bulk zircon concentrates are uniform across the entire pluton (7.7‰ VSMOW), zircon crystals are zoned in δ18O by up to 1.8‰, and when compared to late garnet, show evidence of changing magma chemistry during multiple interactions of the magma with wall rock during crustal transit. The evolution from an early high-δ18O magma [δ18O(WR) = 9.8‰] toward lower values is shown by high-δ18O zircon cores (7.8‰) and lower δ 18O rims (6.8‰). Garnets from the northwest side of the pluton show a final increase in δ18O with rims reaching 8.1‰. In situ REE measurements show zircon is magmatic and grew before garnets. Additionally, δ18O in garnets from the western side of the pluton are consistently higher (avg = 7.3‰) relative to the west (avg = 5.9‰).These δ18O variations in zircon and garnet record different stages of assimilation and fractional crystallization whereby an initially high-δ18O magma partially melted low-δ18O wallrock and was subsequently contaminated near the current level of emplacement by higher δ18O melts. Collectively, the comparison of δ18O zoning in garnet and zircon shows how a peraluminous pluton can be constructed from multiple batches of variably contaminated melts, especially in early stages of arc magmatism where magmas encounter significant heterogeneity of wall-rock assemblages. Collectively, peraluminous magmas in the Sierran arc are limited to small <100 km2 plutons that are intimately associated with metasedimentary wall rocks and often surrounded by later and larger metaluminous tonalite and granodiorite plutons. The general associations suggest that early-stage arc magmas sample crustal heterogeneities in small melt batches, but that with progressive invigoration of the arc, such compositions are more effectively blended with mantle melts in source regions. Thus, peraluminous magmas provide important details of the nascent Sierran arc and pre-batholithic crustal structure.

中文翻译：

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锆石和石榴石中的氧同位素比：加利福尼亚内华达州Dinkey Dome高铝质花岗岩中同化和分步结晶的记录

内华达山脉中部基底岩层中的119 Ma Dinkey Dome岩体是一种高铝质花岗岩，含有岩浆石榴石和锆石，相对于氧同位素比率，它们的分布复杂。晶内SIMS分析测试了岩浆分异过程与准沉积岩部分融化的相对重要性。锆石块体的δ18O值在整个岩体中是均匀的（7.7‰VSMOW），而δ18O中的锆石晶体区域高达1.8‰，与晚石榴石相比，显示出在岩浆多次相互作用期间岩浆化学发生变化的证据。地壳运输过程中的围岩。高δ18O锆石岩心（7.8‰）和低δ18O边缘（6.8‰）显示了从早期的高δ18O岩浆[δ18O（WR）= 9.8‰]到较低值的演变。岩钉西北侧的石榴石最终显示出δ18O的增加，其边缘达到8.1‰。原位稀土元素测量表明锆石为岩浆，并在石榴石之前生长。此外，从p的西侧石榴石中的δ18O相对于西部（avg = 5.9‰）始终较高（avg = 7.3‰）。这些锆石和石榴石中的δ18O变化记录了同化和分步结晶的不同阶段，因此初始阶段高δ18O岩浆部分熔化了低δ18O的围岩，随后在较高的δ18O熔体附近被污染，接近了当前的侵位水平。总的来说，对石榴石和锆石中δ18O分区的比较表明，如何从多批受污染程度不同的熔体中构造出高铝质岩体，特别是在弧岩浆作用的早期阶段，在岩浆作用下，围岩组合体明显地具有非均质性。总体而言，Sierran弧中的高铝质岩浆仅限于小于100 km2的小型岩体，这些岩体与沉积的围岩密切相关，并且通常被较晚和较大的金属辉石和花岗闪长岩岩体包围。普遍的联系表明，早期电弧岩浆在小批量熔体中采样了地壳异质性，但是随着电弧的不断发展，这种成分更有效地与源区的地幔熔体混合。因此，高铝质岩浆提供了新生的Sierran弧和巴特石器时代前地壳结构的重要细节。100 km2的小子，与沉积的围岩密切相关，并且通常被较晚的较大的金属辉石和花岗闪石小子包围。普遍的联系表明，早期电弧岩浆在小批量熔体中采样了地壳异质性，但是随着电弧的不断发展，这种成分更有效地与源区的地幔熔体混合。因此，高铝质岩浆提供了新生的Sierran弧和巴特石器时代前地壳结构的重要细节。100 km2的小子，与沉积的围岩密切相关，并且通常被较晚的较大的金属辉石和花岗闪石小子包围。普遍的联系表明，早期电弧岩浆在小批量熔体中采样了地壳异质性，但是随着电弧的不断发展，这种成分更有效地与源区的地幔熔体混合。因此，高铝质岩浆提供了新生的Sierran弧和巴特石器时代前地壳结构的重要细节。这样的组合物更有效地与源区的地幔熔体混合。因此，高铝质岩浆提供了新生的Sierran弧和巴特石器时代前地壳结构的重要细节。这样的组合物更有效地与源区的地幔熔体混合。因此，高铝质岩浆提供了新生的Sierran弧和巴特石器时代前地壳结构的重要细节。