Reverse fractionation modeling considering energy-constrained assimilation-fractional crystallization is performed to estimate primary magma compositions, degree of crustal contamination, pressure–temperature of equilibrium with mantle, and potential temperatures for the origin of the Paleoproterozoic (~ 2.37–1.88 Ga) basaltic dikes in central and eastern Dharwar Craton and sills and volcanics in the adjoining Cuddapah Basin, southern India. Mineral thermobarometry indicates that the dikes crystallized at upper crustal conditions (~ 1–6 kbar/ ~ 1120–1210 °C). Hence, the reverse fractionation calculations are performed at low pressures by adding olivine + plagioclase + clinopyroxene, olivine + plagioclase and only olivine in equilibrium with melt, and simultaneously subtracting an upper crustal partial melt in small steps until the melt is multiply saturated with lherzolite at a high pressure. The results indicate that the basalts are 5–30% contaminated, and their enriched light rare earth element (REE) patterns can be attributed to upper crustal assimilation. The upper crust was pre-heated to 665–808 °C during dike emplacement. The primary magmas of all basalts were last equilibrated with spinel lherzolite at 10–16.5 kbar/1291–1366 °C, and they resemble pooled polybaric incremental melts generated along a ~ 1450 °C adiabat. The estimated mantle potential temperatures (1293–1515 °C) are similar to Paleoproterozoic ambient mantle temperatures. All basalts and their primary magmas show lower chondrite-normalized Dy_N/Yb_N ratios than the plume-derived mid-Proterozoic Mackenzie dikes of Canadian Shield, and the primary magmas show flat REE patterns indicating spinel lherzolite melting. The low estimated potential temperatures, low Dy_N/Yb_N ratios, and a spinel-bearing mantle source are at odds with an origin of the basalts from mantle plumes.

进行了考虑能量约束同化-分步结晶的反分馏模拟，以估计原生岩浆成分、地壳污染程度、与地幔平衡的压力-温度以及古元古代 (~ 2.37–1.88 Ga) 玄武岩脉起源的潜在温度Dharwar Craton 的中部和东部，以及印度南部毗邻的 Cuddapah 盆地的窗台和火山岩。矿物热压测定表明，岩脉在上地壳条件下结晶（~ 1–6 kbar/ ~ 1120–1210 °C）。因此，通过添加橄榄石 + 斜长石 + 斜长石、橄榄石 + 斜长石和仅与熔体平衡的橄榄石，在低压下进行反向分馏计算，并同时以小步骤减去上地壳部分熔体，直到熔体在高压下被二辉橄榄石多次饱和。结果表明，玄武岩受到 5-30% 的污染，其富集的轻稀土元素 (REE) 模式可归因于上地壳同化作用。在筑堤期间，上地壳被预热到 665–808 °C。所有玄武岩的原生岩浆最后在 10–16.5 kbar/1291–1366 °C 下与尖晶石二辉橄榄石平衡，它们类似于沿 ~ 1450 °C 绝热层产生的混合多元增量熔体。估计的地幔潜在温度 (1293–1515 °C) 与古元古代环境地幔温度相似。所有玄武岩及其原生岩浆均显示较低的球粒陨石归一化 Dy 结果表明，玄武岩受到 5-30% 的污染，其富集的轻稀土元素 (REE) 模式可归因于上地壳同化作用。在筑堤期间，上地壳被预热到 665–808 °C。所有玄武岩的原生岩浆最后在 10–16.5 kbar/1291–1366 °C 下与尖晶石二辉橄榄石平衡，它们类似于沿 ~ 1450 °C 绝热层产生的混合多元增量熔体。估计的地幔潜在温度 (1293–1515 °C) 与古元古代环境地幔温度相似。所有玄武岩及其原生岩浆均显示较低的球粒陨石归一化 Dy 结果表明，玄武岩受到 5-30% 的污染，其富集的轻稀土元素 (REE) 模式可归因于上地壳同化作用。在筑堤期间，上地壳被预热到 665–808 °C。所有玄武岩的原生岩浆最后在 10–16.5 kbar/1291–1366 °C 下与尖晶石二辉橄榄石平衡，它们类似于沿 ~ 1450 °C 绝热层产生的混合多元增量熔体。估计的地幔潜在温度 (1293–1515 °C) 与古元古代环境地幔温度相似。所有玄武岩及其原生岩浆均显示较低的球粒陨石归一化 Dy 所有玄武岩的原生岩浆最后在 10–16.5 kbar/1291–1366 °C 下与尖晶石二辉橄榄石平衡，它们类似于沿 ~ 1450 °C 绝热层产生的混合多元增量熔体。估计的地幔潜在温度 (1293–1515 °C) 与古元古代环境地幔温度相似。所有玄武岩及其原生岩浆均显示较低的球粒陨石归一化 Dy 所有玄武岩的原生岩浆最后在 10–16.5 kbar/1291–1366 °C 下与尖晶石二辉橄榄石平衡，它们类似于沿 ~ 1450 °C 绝热层产生的混合多元增量熔体。估计的地幔潜在温度 (1293–1515 °C) 与古元古代环境地幔温度相似。所有玄武岩及其原生岩浆均显示较低的球粒陨石归一化 Dy_N / Yb _N比值高于加拿大地盾的羽流衍生的中元古代 Mackenzie 岩脉，并且原生岩浆显示出平坦的 REE 模式，表明尖晶石二辉橄榄石熔化。低估计潜在温度、低 Dy _N / Yb _N比率和含尖晶石的地幔源与地幔柱玄武岩的起源不一致。