The origin of the alkaline magmatism, including kimberlites and carbonatites, is believed to be related to deep-seated mantle plumes. A chondritic Earth’s mantle contains very low amounts of alkaline elements, with Na prevailing over K. Consequently, the source of the alkaline rocks cannot be the ‘chondritic’ mantle and most likely a mantle modified by subducted crustal materials. Alkaline magmas and carbonatites appear first in the Mesoarchean (~ 3 Ga) and possibly coincided with the onset of plate tectonics. Melting and degassing of subducted slabs into the deep mantle caused widespread metasomatism and formation of reservoirs enriched in the alkaline and lithophile trace elements. These served as sources of alkaline and carbonatitic magmas, and from ~ 2 Ga onwards of kimberlite magmas. Theoretical and experimental modeling predict the lower mantle and transition zone to be largely composed of bridgmanite, ferropericlase, Ca-Si-perovskite, ringwoodite, wadsleyite, majorite, NAL (a hexagonal aluminous phase of the lower mantle containing Na, Al and K), breyite and carbonates. The alkaline elements, isomorphic in CaSi-perovskite, bridgmanite and NAL, can be released during the ascent of mantle plume and transferred to the melt/fluid-enriched reservoir of carbonatites and alkaline magmas. At ~ 600 km depth where majorite is stable, an extensive fractionation of K and Na occurs, as the partitioning coefficient of Na is an order of magnitude larger than that of K. This results in K enrichment of the metasomatic melt/fluid that contribute to prospective sources of kimberlitic and other deep-mantle K magmas.

碱性岩浆作用的起源，包括金伯利岩和碳酸盐岩，被认为与深层地幔柱有关。球粒状地幔中的碱性元素含量非常低，其中 Na 高于 K。因此，碱性岩石的来源不可能是“球粒状”地幔，而很可能是由俯冲地壳物质改造的地幔。碱性岩浆和碳酸盐岩首先出现在中太古代（~ 3 Ga），可能与板块构造的开始同时发生。俯冲板片熔融脱气进入地幔深部，引起广泛的交代作用，形成富含碱性和亲石微量元素的储层。这些作为碱性和碳酸盐岩浆的来源，以及从~2 Ga 开始的金伯利岩岩浆。理论和实验模型预测下地幔和过渡带主要由桥锰矿、铁方镁石、Ca-Si-钙钛矿、菱镁矿、wadsleyite、majorite、NAL（含有Na、Al和K的下地幔六方铝相）组成，布雷氏石和碳酸盐。CaSi-钙钛矿、布里奇曼岩和 NAL 中的碱性元素可以在地幔柱上升过程中释放出来，并转移到碳酸岩和碱性岩浆的熔体/富流体储层中。在大约 600 公里深度处，多数岩是稳定的，K 和 Na 发生广泛的分馏，因为 Na 的分配系数比 K 的分配系数大一个数量级。这导致交代熔体/流体的 K 富集，有助于金伯利岩和其他深地幔钾岩浆的潜在来源。