Chromite nodule is unique in podiform chromitite of ophiolitic suites and there is no agreement on its petrogenesis. The nodular chromitites of the Kızıldağ ophiolite in southern Turkey contain typical chromite nodules, and here their geochemical compositions and crystallographic orientations have been analyzed to study the formation of nodular orebody and related geodynamic processes. The EBSD data reveal that chromite nodule is composed of a patchwork of chromite grains that have random crystallographic orientations, and all grains have low misorientation angles (<6°) without extensive subgrain rotation. These characteristics are inconsistent with the viewpoint that chromite nodule is emanating from a skeletal chromite core. In addition, chromite crystals in nodules have relatively homogeneous compositions, implying the limited importance of chaotic mixing between two distinct magmas in the formation of chromite nodules. Based on the H₂O contents of olivine and clinopyroxene in chromitite, we calculated that the parental magma of chromitite is hydrous (<~3.48%), but its water content is far less than the required H₂O solubility for exsolution of fluid and vapour phase. Moreover, the dynamic flow of the parental magma should be quasi-laminar due to its low Reynolds number, distinct from the turbulent flow that has long been recognized as a critical factor in forming chromite nodules. When an upward magma flow passes through the lenticular segment of a narrow conduit, some parts will be separated from the remaining forward flow to form a convective circulation in the enlarged area. This convective flow facilitates the melting of pyroxenes along the peridotite wall rock, forming extensive Si- and Cr-rich melt droplets which, in turn, mix with the primitive magma to crystallize chromite grains. Trajectories of these chromite crystals with different sizes highly gather in a quasi-steady area inside the boundary between the convective current and upward ascending magma flow, where allows numerous impacts and collisions between chromite grains, leading to the coalescence of clusters of chromite grains and eventually the formation of chromite nodules. This scenario is underpinned by the laminar flow pattern in the podiform chromitite from the Kızıldağ ophiolite, and may be also transferrable to other ophiolitic chromitite in general.

铬铁矿结核在蛇绿岩组的豆状铬铁矿中是独一无二的，其成因尚无定论。土耳其南部 Kızıldağ 蛇绿岩的球状铬铁矿包含典型的铬铁矿结核，这里已经分析了它们的地球化学成分和晶体学取向，以研究球状矿体的形成和相关的地球动力学过程。EBSD 数据显示，铬铁矿结核由具有随机晶体取向的铬铁矿颗粒拼凑而成，并且所有颗粒都具有低取向角（<6°）而没有广泛的亚晶旋转。这些特征与铬铁矿结核起源于铬铁矿骨架的观点不一致。此外，结核中的铬铁矿晶体成分相对均匀，这意味着两种不同岩浆之间的混沌混合在铬铁矿结核形成中的重要性有限。基于 H₂ O 含量的铬铁矿橄榄石和单斜辉石，我们计算出铬铁矿的母岩浆是含水的（<~3.48%），但其含水量远低于所需的 H ₂O 溶解度，用于流体和汽相的溶出。此外，母岩浆的动态流动因其低雷诺数而应为准层流，这与长期以来被认为是形成铬铁矿结核的关键因素的湍流不同。当向上的岩浆流通过狭窄管道的透镜状段时，某些部分将与剩余的向前流分离，在扩大的区域形成对流环流。这种对流促进辉石沿着橄榄岩围岩熔化，形成大量富含硅和铬的熔滴，这些熔滴又与原始岩浆混合，使铬铁矿颗粒结晶。这些不同尺寸的铬铁矿晶体的轨迹高度聚集在对流和上升岩浆流边界内的准稳态区域内，在该区域允许铬铁矿颗粒之间多次撞击和碰撞，导致铬铁矿颗粒团聚并最终铬铁矿结核的形成。这种情况以来自 Kızıldağ 蛇绿岩的豆状铬铁矿中的层流模式为基础，并且通常也可以转移到其他蛇绿岩铬铁矿。