Abstract We report the first occurrence of magmatic haggertyite (BaFe6Ti5MgO19) from the Miocene lamproites of the West Kimberley region of Western Australia. This contrasts with the metasomatic formation reported in an olivine lamproite host at the type locality, Prairie Creek, Arkansas. Haggertyite occurs in the groundmass of a diamondiferous olivine lamproite pipe in the Ellendale field, and within the large zoned Walgidee Hills lamproite where it forms part of an extensive suite of Ba- and K-bearing titanate and Ti-rich silicate minerals. The haggertyite co-exists with chromian spinel, perovskite, and ilmenite in the Ellendale lamproite, and with priderite and perovskite and, in one locality, with priderite, jeppeite, ilmenite, and perovskite, in the Walgidee Hills lamproite. Unlike priderite and perovskite, which are common groundmass phases in the Ellendale olivine lamproites and present throughout the Walgidee Hills lamproite, haggertyite appears restricted in its occurrence and crystallization interval, with sparse ilmenite apparently mostly crystallizing as an alternative phase. In the Walgidee Hills lamproite the haggertyite-bearing assemblage is succeeded by the Ba-titanate assemblage priderite plus jeppeite in the evolved central part of the body. The haggertyite in the main zone of the Walgidee Hills lamproite has an average composition of B a 0.7 K 0.3 1.0 T i 5.0 F e 2.1 3 + C r 0.1 F e 3.8 2 + M n 0.2 M g 0.6 N a 0.1 12 O 19 $\left(\mathrm{Ba}_{0.7} \mathrm{K}_{0.3}\right)_{1.0}\left(\mathrm{Ti}_{5.0} \mathrm{Fe}_{2.1}^{3+} \mathrm{Cr}_{0.1} \mathrm{Fe}_{3.8}^{2+} \mathrm{Mn}_{0.2} \mathrm{Mg}_{0.6} \mathrm{Na}_{0.1}\right)_{12} \mathrm{O}_{19}$and is thus very similar to the original haggertyite described from xenoliths in the Prairie Creek lamproite apart from being poorer in Cr and Ni. Haggertyite in the groundmass of the Ellendale olivine lamproite and the central zone of the Walgidee Hills lamproite, in addition to variations in Mg and Cr, show significant variation in Ti and Fe contents and in calculated Fe3+ and Fe2+. A linear inverse relationship between Ti and Fe, and Ti and Fe3+, indicates that Fe3+ is accommodated by the coupled substitution Ti4+ + Fe2+ ⇆ Fe3+. A marked trend to higher Fe3+ in the haggertyite in Ellendale 9 olivine lamproite is ascribed to increasing oxidation during crystallization, with fO2 estimated from the olivine- spinel thermometer and oxygen barometer at Dlog FMQ = –1 to +3 at temperatures of 790–660 °C. The haggertyite in the central zone of the Walgidee Hills lamproite, in contrast, shows a marked trend to Fe2+ enrichment, which is associated with decreasing Fe in perovskite. This is inferred to indicate formation under more reducing conditions, but suficiently oxidized to permit Fe3+ in co-existing priderite and jeppeite. Trace-element analysis by LA-ICP-MS shows the Walgidee Hills haggertyite contains minor amounts of Na, Si, Ca, V, Co, Zn, Sr, Zr, Nb, and Pb, and only traces of Al, P, Sc, Rb, REE, Hf, and Ta. Moreover, the haggertyite is preferentially enriched in certain lithophile (Ba, Sr), siderophile (Mn, Fe, Co, Ni), and chalcophile (Zn, Pb) elements relative to co-existing priderite. Haggertyite crystallization appears to be a consequence not only of the very high Ba, Ti, and K contents of the lamproite, but of relatively high-Fe concentrations and low temperatures in evolved olivine lamproite magma with the Fe3+/Fe2+ ratio determined by the prevailing f O 2 . $f_{\mathrm{O}_{2}}.$The new data suggest that haggertyite might also be present but previously unrecognized in the evolved groundmass of other olivine lamproites. Haggertyite is one of an increasing number of new minerals in upper mantle rocks and volcanics derived from the upper mantle hosting large-ion-lithophile and high field strength cations.

中文翻译：

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西澳大利亚西金伯利地区橄榄石菱镁矿中的岩浆哈格提石

摘要 我们报告了西澳大利亚西金伯利地区中新世菱镁矿中首次出现的岩浆哈格铁矿 (BaFe6Ti5MgO19)。这与阿肯色州草原溪的典型产地橄榄石菱镁矿宿主中报道的交代形成形成对比。Haggertyite 出现在 Ellendale 油田的含金刚石橄榄石菱镁矿管的地块中，以及大型分区 Walgidee Hills 菱镁矿中，在那里它构成了大量含 Ba 和 K 的钛酸盐和富 Ti 硅酸盐矿物的一部分。在 Ellendale 菱镁矿中，哈格钛矿与铬尖晶石、钙钛矿和钛铁矿共存，在 Walgidee Hills 菱镁矿中与紫铜矿和钙钛矿共存，并在一个地方与紫铁矿、jeppeite、钛铁矿和钙钛矿共存。不同于骄傲石和钙钛矿，它是 Ellendale 橄榄石菱镁矿中常见的基体相，存在于 Walgidee Hills 菱镁矿中，哈格铁石的出现和结晶间隔似乎受到限制，稀疏的钛铁矿显然主要作为替代相结晶。在 Walgidee Hills 菱镁矿中，含哈格提石的组合由 Ba-titanate 组合的骄傲石和在进化的身体中央部分的 jeppeite 继承。Walgidee Hills 菱镁矿主带中的哈格铁矿的平均成分为 B a 0.7 K 0.3 1.0 T i 5.0 F e 2.1 3 + C r 0.1 F e 3.8 2 + M n 0.2 M g 0.6 N a 0.1 12 O 19 $\left(\mathrm{Ba}_{0.7} \mathrm{K}_{0.3}\right)_{1.0}\left(\mathrm{Ti}_{5.0} \mathrm{Fe}_{2.1} ^{3+} \mathrm{Cr}_{0.1} \mathrm{Fe}_{3.8}^{2+} \mathrm{Mn}_{0.2} \mathrm{Mg}_{0.6} \mathrm{Na }_{0. 1}\right)_{12} \mathrm{O}_{19}$ 因此，除了在 Cr 和 Ni 中较差之外，它与从草原溪菱镁矿中的捕虏体中描述的原始哈格提岩非常相似。除了 Mg 和 Cr 的变化外，Ellendale 橄榄石菱镁矿的基质和 Walgidee Hills 菱镁矿的中心带中的哈格铁矿显示出 Ti 和 Fe 含量以及计算的 Fe3+ 和 Fe2+ 的显着变化。Ti 和 Fe 以及 Ti 和 Fe3+ 之间的线性反比关系表明 Fe3+ 被耦合置换 Ti4+ + Fe2+ ⇆ Fe3+ 所容纳。Ellendale 9 橄榄石菱镁矿的八角铁中 Fe3+ 较高的显着趋势归因于结晶过程中氧化增加，从橄榄石尖晶石温度计和氧气压计测得的 fO2 在 Dlog FMQ = –1 至 +3，温度为 790–660 ° C。相比之下，Walgidee Hills 菱镁矿中心区的哈格铁矿显示出明显的 Fe2+ 富集趋势，这与钙钛矿中 Fe 的减少有关。推断这表明在更多还原条件下形成，但充分氧化以允许 Fe3+ 在共存的菱镁矿和 jeppeite 中。通过 LA-ICP-MS 进行的微量元素分析显示 Walgidee Hills 菱镁矿含有少量的 Na、Si、Ca、V、Co、Zn、Sr、Zr、Nb 和 Pb，只有痕量的 Al、P、Sc、 Rb、REE、Hf 和 Ta。此外，与共存的菱铁矿相比，菱铁矿优先富集某些亲石体（Ba、Sr）、亲铁体（Mn、Fe、Co、Ni）和亲硫体（Zn、Pb）元素。Haggertyite 结晶似乎不仅是由于菱镁矿的 Ba、Ti 和 K 含量非常高，但在演化出的橄榄石菱镁矿岩浆中，Fe3+/Fe2+ 比率相对较高，Fe 浓度较低，温度较低，Fe3+/Fe2+ 比率由主要 fO2 决定。$f_{\mathrm{O}_{2}}.$新数据表明，在其他橄榄石菱镁矿的进化地块中，可能也存在哈格提石，但之前未被发现。Haggertyite 是上地幔岩石和火山岩中越来越多的新矿物之一，它们源自上地幔，含有大离子亲石物质和高场强阳离子。