The Quaternary Big Pine (BP) volcanic field in eastern California is notable for the occurrence of mantle xenoliths in several flows. This points to rapid ascent of basalt through the crust and precludes prolonged storage in a crustal reservoir. In this study, the hypothesis of phenocryst growth during ascent is tested for several basalts (13–7 wt% MgO) and shown to be viable. Phenocrysts of olivine and clinopyroxene frequently display diffusion‐limited growth textures, and clinopyroxene compositions are consistent with polybaric crystallization. When the most Mg‐rich olivine in each sample is paired with the whole‐rock composition, resulting (olivine‐melt) values (0.31–0.36) match those calculated from literature models (0.32–0.36). Application of a Mg‐ and a Ni‐based olivine‐melt thermometer from the literature, both calibrated on the same experimental data set, leads to two sets of temperatures that vary linearly with whole‐rock MgO wt%. Because the Ni thermometer is independent of water content, it provides the actual temperature at the onset of olivine crystallization (1247–1097°C), whereas the Mg thermometer gives the temperature under anhydrous conditions and thus allows ΔT (=T_Mg − T_Ni = depression of liquidus due to water) to be obtained. The average ΔT for all samples is ~59°C, which is consistent with analyzed water contents of 1.5–3.0 wt% in olivine‐hosted melt inclusions from the literature. Because the application of olivine‐melt thermometry/hygrometry at the liquidus only requires microprobe analyses of olivine combined with whole‐rock compositions, it can be used to obtain large global data sets of the temperature and water contents of basalts from different tectonic settings.

中文翻译：

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大松火山岩玄武岩中橄榄石在上升过程中快速变晶现象的证据：橄榄石熔体温度法和湿度计在液相线上的应用

加利福尼亚州东部的第四纪大松（BP）火山岩田在几次流动中都存在地幔异种岩。这表明玄武岩可以通过地壳迅速上升，因此不能长时间储存​​在地壳储层中。在这项研究中，针对几种玄武岩（13–7 wt％MgO）测试了上升过程中隐晶石生长的假说，并证明是可行的。橄榄石和clinopyroxene的透晶石经常显示出扩散受限的生长纹理，clinopyroxene的组成与多晶的结晶相一致。当每个样品中最富镁的橄榄石与整个岩石成分配对时，（橄榄石熔体）值（0.31-0.36）与文献模型（0.32-0.36）计算出的值匹配。应用文献中的Mg和Ni基橄榄石熔体温度计（均在同一实验数据集上进行校准）会导致两组温度随整个岩石中MgO的重量百分比线性变化。因为镍温度计与水含量无关，所以它提供了橄榄石结晶开始时的实际温度（1247-1097°C），而镁温度计给出了无水条件下的温度，因此允许ΔT（= T _Mg  −  T _Ni  =由于水导致的液相线降低）。平均ΔT所有样品的温度均为〜59°C，这与文献中所分析的橄榄石熔体包裹体中1.5-3.0 wt％的水分含量相符。由于在液相线上使用橄榄石熔体温度/湿度法仅需对橄榄石和全岩石成分进行微探针分析，因此可用于获取来自不同构造环境的玄武岩温度和水含量的大型全局数据集。