The temperature-dependent exchange of Ni and Mg between garnet and olivine in mantle peridotite is an important geothermometer for determining temperature variations in the upper mantle and the diamond potential of kimberlites. Existing calibrations of the Ni-in-garnet geothermometer show considerable differences in estimated temperature above and below 1100 °C hindering its confident application. In this study, we present the results from new synthesis experiments conducted on a piston cylinder apparatus at 2.25–4.5 GPa and 1100–1325 °C. Our experimental approach was to equilibrate a Ni-free Cr-pyrope-rich garnet starting mixture made from sintered oxides with natural olivine capsules (Ni_olv ≅ 3000 ppm) to produce an experimental charge comprised entirely of peridotitic pyrope garnet with trace abundances of Ni (10–100 s of ppm). Experimental runs products were analysed by wave-length dispersive electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We use the partition coefficient for the distribution of Ni between our garnet experimental charge and the olivine capsule \(\left( {{\text{lnD}}_{{{\text{grt}}/{\text{olv}}}}^{{{\text{Ni}}}} ; \frac{{{\text{Ni}}_{{{\text{grt}}}} }}{{{\text{Ni}}_{{{\text{olv}}}} }}} \right)\), the Ca mole fraction in garnet (\({\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Ca}};\) Ca/(Ca + Fe + Mg)), and the Cr mole fraction in garnet (\({\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Cr}};\) Cr/(Cr + Al)) to develop a new formulation of the Ni-in-garnet geothermometer that performs more reliably on experimental and natural datasets than existing calibrations. Our updated Ni-in-garnet geothermometer is defined here as:

\(T \left(^\circ{\rm C} \right)=\frac{-8254.568}{\left(\left( {\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Ca}} \times 3.023 \right)+\left({\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Cr}} \times 2.307 \right)+\left({\mathrm{lnD}}_{\frac{\mathrm{grt}}{\mathrm{olv}}}^{\mathrm{Ni}} - 2.639 \right)\right)}-273\pm 55\)

where \({\mathrm{D}}_{\mathrm{grt}/\mathrm{olv}}^{\mathrm{Ni}}= \frac{{\mathrm{Ni}}_{\mathrm{grt}}}{{\mathrm{Ni}}_{\mathrm{olv}}},\) Ni is in ppm, \({\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Ca}}\) = Ca/(Ca + Fe + Mg) in garnet, and \({\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Cr}}\)= Cr/(Cr + Al) in garnet. Our updated Ni-in-garnet geothermometer can be applied to garnet peridotite xenoliths or monomineralic garnet xenocrysts derived from disaggregation of a peridotite source. Our calibration can be used as a single grain geothermometer by assuming an average mantle olivine Ni concentration of 3000 ppm. To maximise the reliability of temperature estimates made from our Ni-in-garnet geothermometer, we provide users with a data quality protocol method which can be applied to all garnet EPMA and LA-ICP-MS analyses prior to Ni-in-garnet geothermometry. The temperature uncertainty of our updated calibration has been rigorously propagated by incorporating all analytical and experimental uncertainties. We have found that our Ni-in-garnet temperature estimates have a maximum associated uncertainty of ± 55 °C. The improved performance of our updated calibration is demonstrated through its application to previously published experimental datasets and on natural, well-characterised garnet peridotite xenoliths from a variety of published datasets, including the diamondiferous Diavik and Ekati kimberlite pipes from the Lac de Gras kimberlite field, Canada. Our new calibration better aligns temperature estimates using the Ni-in-garnet geothermometer with those estimated by the widely used (Nimis and Taylor, Contrib Mineral Petrol 139:541–554, 2000) enstatite-in-clinopyroxene geothermometer, and confirms an improvement in performance of the new calibration relative to existing versions of the Ni-in-garnet geothermometer.

地幔橄榄岩中石榴石和橄榄石之间镍和镁的温度依赖性交换是确定地幔上部温度变化和金伯利岩金刚石势的重要地热仪。镍石榴石地热仪的现有校准表明，在1100°C上下的估计温度存在很大差异，这阻碍了其信心十足的应用。在这项研究中，我们介绍了在2.25–4.5 GPa和1100–1325°C的活塞缸装置上进行的新合成实验的结果。我们的实验方法是平衡由烧结氧化物和天然橄榄石胶囊制成的无镍富铬-石榴石石榴石起始混合物（Ni _olv ≅3000 ppm）以产生全部由橄榄石型焦榴石石榴石和微量Ni（10-100 s ppm）组成的实验电荷。通过波长色散电子探针微分析（EPMA）和激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）分析了实验产品。我们使用石榴石实验电荷和橄榄石胶囊\（\ left（{{\ text {lnD}} _ {{{\ text {grt}} / {\ text {olv}} }} ^ {{{\ text {Ni}}}}; \ frac {{{\ text {Ni}} __ {{{\ text {grt}}}}}} {{{\ text {Ni}} __ {{{\ text {olv}}}}}}}（\ right）\），石榴石中的Ca摩尔分数（\（{\ mathrm {X}} _ {\ mathrm {grt}} ^ {\ mathrm {Ca }}; \） Ca /（Ca + Fe + Mg）），石榴石中的Cr摩尔分数（\（{\ mathrm {X}} _ {\ mathrm {grt}} ^ {\ mathrm {Cr}}; \）Cr /（Cr + Al））来开发一种新的镍石榴石地热仪配方，其在实验和自然数据集上的性能要比现有的标定方法更可靠。我们更新后的镍石榴石地热仪的定义为：

\（T \ left（^ \ circ {\ rm C} \ right）= \ frac {-8254.568} {\ left（\ left（{\ mathrm {X}} _ {\ mathrm {grt}} ^ {\ mathrm {Ca}} \ times 3.023 \ right）+ \ left（{\ mathrm {X}} _ {\ mathrm {grt}} ^ {\ mathrm {Cr}} \ times 2.307 \ right）+ \ left（{\ mathrm {lnD}} _ {\ frac {\ mathrm {grt}} {\ mathrm {olv}}} ^ {\ mathrm {Ni}}-2.639 \ right）\ right）}-273 \ pm 55 \）

其中\（{\ mathrm {D}} _ {\ mathrm {grt} / \ mathrm {olv}} ^ {\ mathrm {Ni}} = \ frac {{\ mathrm {Ni}} _ {\ mathrm {grt} }} {{\ mathrm {Ni}} _ {\ mathrm {olv}}}，\） Ni以ppm为单位，\（{\ mathrm {X}} _ {\ mathrm {grt}} ^ {\ mathrm {Ca }} \）  =石榴石中的Ca /（Ca + Fe + Mg），和\（{\ mathrm {X}} _ {\ mathrm {grt}} ^ {\ mathrm {Cr}} \\）=石榴石中的Cr /（Cr + Al）。我们更新后的镍石榴石地热仪可以应用于石榴石橄榄石异种岩或源自橄榄岩来源分解的单矿物石榴石异种晶。假设平均地幔橄榄石镍浓度为3000 ppm，我们的校准可以用作单粒地热仪。为了最大程度地利用我们的石榴石地热仪进行温度估算，我们为用户提供了一种数据质量协议方法，该方法可以应用于石榴石地热仪之前的所有石榴石EPMA和LA-ICP-MS分析。通过合并所有分析和实验不确定性，我们严格校准后的温度不确定性得到了严格的传播。我们发现，石榴石镍温度估计值的最大相关不确定度为±55°C。通过将其应用到先前发布的实验数据集以及来自各种已公开数据集的天然，特征明确的石榴石橄榄岩橄榄石异质体上，我们可以证明我们更新后的校准性能得到改善，包括来自Lac de Gras金伯利岩田的含钻石的Diavik和Ekati金伯利岩管，加拿大。我们的新校准更好地使用了石榴石中的镍地热仪与由广泛使用的（尼米斯和泰勒，Contrib Mineral Petrol 139：541-554，2000）钙钛矿-斜辉石地热仪的温度估算值相吻合，并证实了改进的方法。相对于现有版本的镍石榴石地热仪的新校准性能。来自各种已公开数据集的特征丰富的石榴石橄榄岩橄榄岩异质岩，包括来自加拿大Lac de Gras金伯利岩田的带钻石的Diavik和Ekati金伯利岩管。我们的新校准更好地使用了石榴石中的镍地热仪与由广泛使用的（尼米斯和泰勒，Contrib Mineral Petrol 139：541-554，2000）钙钛矿-斜辉石地热仪的温度估算值相吻合，并证实了改进的方法。相对于现有版本的镍石榴石地热仪的新校准性能。来自各种已公开数据集的特征丰富的石榴石橄榄岩橄榄岩异质岩，包括来自加拿大Lac de Gras金伯利岩田的带钻石的Diavik和Ekati金伯利岩管。我们的新校准更好地使用了石榴石中的镍地热仪与由广泛使用的（尼米斯和泰勒，Contrib Mineral Petrol 139：541-554，2000）钙钛矿-斜辉石地热仪的温度估算值相吻合，并证实了改进的方法。相对于现有版本的镍石榴石地热仪的新校准性能。