The pressure dependence of the exchange of Cr between clinopyroxene and garnet in peridotite is applicable as a geobarometer for mantle-derived Cr-diopside xenocrysts and xenoliths. The most widely used calibration (Nimis and Taylor Contrib Miner Petrol 139: 541–554, 2000; herein NT00) performs well at pressures below 4.5 GPa, but has been shown to consistently underestimate pressures above 4.5 GPa. We have experimentally re-examined this exchange reaction over an extended pressure, temperature, and compositional range using multi-anvil, belt, and piston cylinder apparatuses. Twenty-nine experiments were completed between 3–7 GPa, and 1100–1400 °C in a variety of compositionally complex lherzolitic systems. These experiments are used in conjunction with several published experimental datasets to present a modified calibration of the widely-used NT00 Cr-in-clinopyroxene (Cr-in-cpx) single crystal geobarometer. Our updated calibration calculates P (GPa) as a function of T (K), CaCr Tschermak activity in clinopyroxene \(\left( {a_{{{\text{CaCrTs}}}}^{{{\text{cpx}}}} } \right)\), and Cr/(Cr + Al) (Cr#) in clinopyroxene. Rearranging experimental results into a 2n polynomial using multiple linear regression found the following expression for pressure:

\(P\left( {{\text{GPa}}} \right) = 11.03 + \left( { - T{ }\left( {\text{K}} \right){\text{ ln}}(a_{{{\text{CaCrTs}}}}^{{{\text{cpx}}}} ) \times 0.001088{ }} \right) + \left( {1.526 \times {\text{ln}}\left( {\frac{{{\text{Cr}}\#^{{{\text{cpx}}}} }}{{T{ }\left( {\text{K}} \right)}}} \right)} \right){ }\)

where \({\text{Cr}}\#^{{{\text{cpx}}}} = \left( {\frac{{{\text{Cr}}}}{{{\text{Cr}} + {\text{Al}}}}} \right)\), \(a_{{{\text{CaCrTs}}}}^{{{\text{cpx}}}} = {\text{Cr}} - 0.81 \cdot {\text{Cr}}\#^{{{\text{cpx}}}} \cdot \left( {{\text{Na}} + {\text{K}}} \right),\) with all mineral components calculated assuming six oxygen anions per formula unit in clinopyroxene.

Temperature (K) may be calculated through a variety of geothermometers, however, we recommend the NT00 single crystal, enstatite-in-clinopyroxene (en-in-cpx) geothermometer. The pressure uncertainty of our updated calibration has been propagated by incorporating all analytical and experimental uncertainties. We have found that pressure estimates below 4 GPa, between 4–6 GPa and above 6 GPa have associated uncertainties of 0.31, 0.35, and 0.41 GPa, respectively. Pressures calculated using our calibration of the Cr-in-cpx geobarometer are in good agreement between 2–7 GPa, and 900–1400 °C with those estimated from widely-used two-phase geobarometers based on the solubility of alumina in orthopyroxene coexisting with garnet. Application of our updated calibration to suites of well-equilibrated garnet lherzolite and garnet pyroxenite xenoliths and xenocrysts from the Diavik-Ekati kimberlite and the Argyle lamproite pipes confirm the accuracy and precision of our modified geobarometer, and show that PT estimates using our revised geobarometer result in systematically steeper paleogeotherms and higher estimates of the lithosphere‒asthenosphere boundary compared with the original NT00 calibration.

橄榄岩中斜辉石与石榴石之间Cr交换的压力依赖性可作为地幔来源的Cr-透辉石异晶和异岩的地压计。最广泛使用的校准（Nimis和Taylor Contrib Miner Petrol 139：541-554，2000；此处为NT00）在压力低于4.5 GPa时表现良好，但已证明始终低估压力高于4.5 GPa。我们已经使用多砧，皮带和活塞汽缸装置在扩展的压力，温度和成分范围内通过实验重新检查了该交换反应。在3–7 GPa和1100–1400°C之间完成了29个实验，这些实验是由多种组成复杂的左沸石系统组成的。这些实验与几个已发布的实验数据集结合使用，以提供对广泛使用的NT00斜环茂铬（Cr-cpx）单晶气压计的修正校准。我们更新的校准计算P（GPa）作为T（K）的函数，斜发rox烯中的CaCr Tschermak活性\（\ left（{a _ {{{\ text {CaCrTs}}}} ^ {{{{\ text {cpx}}}}} \右）\）以及斜ino中的Cr /（Cr + Al）（Cr＃）。使用多重线性回归将实验结果重新排列为2 n多项式，发现压力的以下表达式：

\（P \ left（{{\ text {GPa}}} \ right）= 11.03 + \ left（{-T {} \ left（{\ text {K}} \ right）{\ text {ln}}（ a _ {{{\ text {CaCrTs}}}} ^ {{{\ text {cpx}}}}}）\ times 0.001088 {}} \ right）+ \ left（{1.526 \ times {\ text {ln}} \\ left（{\ frac {{{\ text {Cr}} \＃^ {{{\ text {cpx}}}}}}} {{T {} \ left（{\ text {K}} \ right）}}} } \是的是的）{ }\）

其中\（{\ text {Cr}} \＃^ {{{\ text {cpx}}}} = \ left（{\ frac {{{\ text {Cr}}}} {{{\ text {Cr} } + {\ text {Al}}}} \ right）\），\（a _ {{{\ text {CaCrTs}}}} ^ {{{\\ t​​ext {cpx}}}} = {\ text {Cr }}-0.81 \ cdot {\ text {Cr}} \＃^ {{{\ text {cpx}}}} \ cdot \ left（{{\ text {Na}} + {\ text {K}}} \右），\），并假设每个配方单位在斜ino中含有六个氧阴离子，计算出所有矿物成分。

温度（K）可以通过多种地热仪计算得出，但是，我们建议使用NT00单晶，斜长辉石中的顽辉石（en-in-cpx）地热仪。通过合并所有分析和实验不确定性，已经传播了我们最新校准的压力不确定性。我们发现，低于4 GPa，介于4-6 GPa和高于6 GPa之间的压力估计值分别具有0.31、0.35和0.41 GPa的不确定性。使用我们的Cr-in-cpx气压计校准计算得出的压力在2-7 GPa和900-1400°C之间与根据广泛使用的两相气压计估计的压力一致，该两相气压计基于氧化铝在邻苯二甲rox中与氧化铝共存的溶解度。石榴石