Magmatic products of the Karoo Large Igneous Province can be divided into a volumetrically dominant, compositionally uniform low‐Ti tholeiitic suite, and a subordinate, geographically restricted, compositionally diverse, incompatible‐rich high‐Ti suite. High‐Ti picrites contain up to 2,400 ppm Sr, 1,900 ppm Ba, and 550 ppm Zr, which seems unusual for olivine‐enriched rocks. We studied six Karoo picrites to determine the phase(s) in which Sr resides. Samples consist of 10–30% olivine phenocrysts in a groundmass of brown glass, augite, feldspar, ilmenite, and apatite. Glass compositions vary, but are generally evolved, ranging from basaltic trachyandesite to dacite. X‐ray intensity maps demonstrate that most of the Sr resides in the glasses, and to a lesser extent, in feldspars, if present. Some samples contain two texturally and compositionally distinct glasses, best modeled in terms of magma hybridization: variably accumulated olivine phenocrysts surrounded by evolved Sr‐rich (to 9,470 ppm) Type 2 melts formed by extensive olivine fractionation were infiltrated by chemically distinct Type 1 melts. Upon eruption, Type 2 melt quenched to minor glass around olivine phenocrysts, and the dominant Type 1 glass acquired its evolved composition by quench crystallization of groundmass mineral phases. Both glasses are rich in H₂O (up to 3.8 wt. %) but are nearly devoid of CO₂. Calculated parental melts have much higher K₂O and incompatible trace elements (e.g., Sr or Ba >1,200 ppm) relative to low‐Ti tholeiites. The unusual parental melt compositions imply derivation by small degrees of partial melting from SCLM mantle sources enriched in Sr and other incompatibles.

中文翻译：

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来自Karoo大火成岩省的富含Sr的玻璃状Pic石正在演化，而不是原始岩浆岩

卡鲁大火成岩省的岩浆产品可分为体积占优势的，成分均匀的低Ti含硫量套件，以及从属的，受地域限制，组成多样的，不相容的高Ti套件。高钛微晶岩含有高达2,400 ppm的Sr，1,900 ppm的Ba和550 ppm的Zr，这对于富含橄榄石的岩石来说似乎并不常见。我们研究了六种卡鲁（Karoo）微粉，以确定Sr所处的相。样品由褐色玻璃，碎石，长石，钛铁矿和磷灰石中的10–30％橄榄石表晶组成。玻璃组成各不相同，但通常会发生变化，从玄武岩菱锰矿到钠钙铁矿。X射线强度图表明，大部分Sr都存在于玻璃杯中，如果存在，则存在于长石中，程度较小。一些样品包含两种在质地和成分上不同的玻璃，这在岩浆杂交方面是最好的模型：由大量的橄榄石分馏形成的富Sr（至9,470 ppm）的2型熔体包围的可变积累的橄榄石表晶被化学性质独特的1型熔体渗透。喷发后，类型2的熔体淬火至橄榄石表晶周围的次要玻璃，而占主导地位的类型1的玻璃则通过对地基矿物相的淬火结晶获得了其演化的成分。两种眼镜都富含H 2型熔体淬火至橄榄石表晶周围的次要玻璃，而占主导地位的1型玻璃则通过对地基矿物相进行淬火结晶来获得其演化的成分。两种眼镜都富含H 2型熔体淬火至橄榄石表晶周围的次要玻璃，而占主导地位的1型玻璃则通过对地基矿物相进行淬火结晶来获得其演化的成分。两种眼镜都富含H₂ O（最高3.8 wt。％），但几乎没有CO ₂。相对于低钛高铝红柱石，计算出的母体熔体具有更高的K ₂ O和不相容的痕量元素（例如，Sr或Ba> 1,200 ppm）。异常的母体熔体成分暗示着从少量富含Sr和其他不相容物质的SCLM地幔源中进行了部分熔融。