The Singhbhum Craton in eastern India is host to at least seven sets of mafic dyke swarms. Four previously dated swarms (studied here) include the NNE-trending Keshargaria (ca. 2.80 Ga) and Ghatgaon (ca. 2.76 - 2.75 Ga) swarms, the ENE-trending Kaptipada swarm (ca. 2.26 Ga), and the ESE-trending Pipilia swarm (ca.1.76 Ga). The dykes range in composition from basalt to andesite and have transitional tholeiitic to calc-alkaline affinities. They show intra- and inter-swarm geochemical and Sr-Nd isotopic heterogeneities and have SiO₂ content ranging from 47 to 60 wt.%. The chondrite normalized REE patterns show enrichment in LREE and the Primitive-Mantle normalized multi-element patterns show elevated U, Th, Cs, Rb, K, and Pb; and depletion in Nb, Ta, and Ti. These characteristics indicate involvement of crustal component in the petrogenesis of these dykes. The dykes of different swarms have variable ⁸⁷Sr/⁸⁶Sr_i and ε_Nd(i) values, which define a crust-like isotopic growth trajectory with time from a common chondritic to depleted source that was enriched contemporaneously with the formation of the crustal rocks of the Singhbhum Craton. The isotope data indicate involvement of older enriched crustal material in the petrogenesis of these dykes. Variable but mostly high (compared to similarly evolved magmas) Ni (40 - 590 ppm), Cr (40 - 1110 ppm), and V (120 - 434 ppm) contents particularly of the most primitive dykes indicate that parental melts were in equilibrium with mantle peridotite and experienced only minor fractional crystallization of olivine, pyroxene, and magnetite. The Sr-Nd isotope ratios do not show any correlation with differentiation indices which indicates that the melts were not modified significantly by crustal assimilation during ascent and emplacement. The crust-like secular trend of the Sr and Nd isotopic compositions suggests that the enriched crustal material was incubated in the mantle (i.e., metasomatized lithospheric mantle) for a long time and this source was periodically tapped leading to multiple dyke emplacement events over at least 1 Gyr. The recycled crustal material played a role in metasomatizing the subcontinental lithospheric mantle prior to ca. 2.80 Ga. Mantle plume activity triggered melting of the metasomatized lithospheric mantle many times, leading to the emplacement of mafic dykes of different generations across the craton.

印度东部的Singhbhum Craton至少有七套铁质岩堤群。四个以前约会的群（在这里研究）包括NNE趋势Keshargaria（约2.80 Ga）和Ghatgaon（约2.76-2.75 Ga），ENE趋势Kaptipada群（约2.26 Ga）和ESE趋势Pipilia群（ca.1.76 Ga）。堤坝的成分范围从玄武岩到安山岩，并具有过渡性的向钙碱过渡的亲和力。它们显示出群内和群内地球化学和Sr-Nd同位素异质性，并具有SiO ₂含量范围为47-60重量％。球粒陨石归一化的REE模式显示出富含LREE，原始幔幔归一化的多元素模式显示出升高的U，Th，Cs，Rb，K和Pb。Nb，Ta和Ti的耗尽。这些特征表明地壳成分参与了这些堤的成岩作用。不同群的堤坝的变量为⁸⁷ Sr / ⁸⁶ Sr _i和εNd _（i）这些值定义了从普通软骨到贫化源随时间变化的类地壳同位素生长轨迹，该源随着Singhbhum Craton地壳岩石的形成而同时富集。同位素数据表明，较早富集的地壳物质参与了这些堤的成岩作用。Ni（40-590 ppm），Cr（40-1110 ppm）和V（120-434 ppm）含量可变但大多为高（与类似演化的岩浆相比），特别是最原始的堤坝表明，母体熔体与地幔橄榄岩，仅经历了橄榄石，辉石和磁铁矿的小部分结晶。Sr-Nd同位素比与分化指数没有任何相关性，这表明在上升和安置过程中，地壳同化作用并没有明显地改变熔体。Sr和Nd同位素组成的地壳状长期趋势表明，富集的地壳物质在地幔（即交代岩石圈地幔）中孵育了很长一段时间，并且该源被周期性地挖掘，导致至少在至少30年间发生了多次堤坝定位事件。 1吉尔。约地壳之前，再循环的地壳物质在亚大陆岩石圈地幔的交代作用中发挥了作用。2.80 Ga。地幔柱的羽化活动多次触发了交代岩石圈地幔的融化，导致克拉通上不同世代的铁质岩浆岩的侵位。Sr和Nd同位素组成的地壳状长期趋势表明，富集的地壳物质在地幔（即交代岩石圈地幔）中孵育了很长一段时间，并且该源被周期性地挖掘，导致至少在至少30年间发生了多次堤坝定位事件。 1吉尔。约地壳之前，再循环的地壳物质在亚大陆岩石圈地幔的交代作用中发挥了作用。2.80 Ga。地幔柱的羽化活动多次触发了交代岩石圈地幔的融化，导致克拉通上不同世代的铁质岩浆岩的侵位。Sr和Nd同位素组成的地壳状长期趋势表明，富集的地壳物质在地幔（即交代岩石圈地幔）中孵育了很长一段时间，并且该源被周期性地挖掘，导致至少在至少30年间发生了多次堤坝定位事件。 1吉尔。约地壳之前，再循环的地壳物质在亚大陆岩石圈地幔的交代作用中发挥了作用。2.80 Ga。地幔柱的羽化活动多次触发了交代的岩石圈地幔的融化，导致克拉通上不同世代的铁质岩浆岩的侵位。约地壳之前，再循环的地壳物质在亚大陆岩石圈地幔的交代作用中发挥了作用。2.80 Ga。地幔柱的羽化活动多次触发了交代岩石圈地幔的融化，导致克拉通上不同世代的铁质岩浆岩的侵位。约地壳之前，再循环的地壳物质在亚大陆岩石圈地幔的交代作用中发挥了作用。2.80 Ga。地幔柱的羽化活动多次触发了交代岩石圈地幔的融化，导致克拉通上不同世代的铁质岩浆岩的侵位。