Determination of the nature of magma flow (vertical or lateral) from rock fabrics in a dyke swarm holds significant importance in deciphering its emplacement mechanism, depth of magma chamber and its association with mantle plumes. Nandurbar–Dhule dyke swarm from Western India consists of ~ 210 mappable, tholeiitic, large, linear dykes intruding the country rocks of Deccan basalt. We discuss here the development of flow-controlled rock fabrics in these dykes as a function of their thicknesses. Magnetic fabric obtained from anisotropy of magnetic susceptibility (AMS) analysis of the samples collected from these dykes was used as a proxy for rock (flow) fabric. Samples from the central parts of the thicker dykes (strike perpendicular thickness > 10 m) show random and inconsistent development of magnetic fabrics than their marginal counterparts. Petrography suggests the development of relatively clear shape-preferred orientations of the elongated mineral grains only at the margin of a thick dyke. Thinner dykes (strike perpendicular thickness < 10 m) show both consistent magnetic fabrics and clear shape-preferred orientations. We propose that the center of a thick dyke fails to provide (due to high flow velocity, slower cooling rate, lack of friction-induced shearing, and draining back of magma) a favorable condition where (a) flow fabric can efficiently develop and (b) magnetic fabric can effectively mimic the flow fabric. Thinner dykes and the margins of the thicker dykes are, hence, better candidates for observing flow fabrics represented by magnetic fabrics. This work is also motivated by the reservations expressed by earlier researchers in using the AMS technique for magma flow characterization, especially for giant dyke swarms. We have critically evaluated their reservations in light of our results and commented on the applicability of the AMS technique on such studies.

确定堤防群中岩质岩浆流动（垂直或横向）的性质，对破译其进位机制，岩浆室深度及其与地幔柱的联系具有重要意义。来自印度西部的Nandurbar–Dhule堤防群包括〜210个可映射的，可塑的，大的，线性的堤防，这些堤防侵入了Deccan玄武岩的乡村岩石中。我们在这里讨论这些堤坝中流量控制岩石织物随厚度变化的发展。通过对从这些堤坝收集的样品的磁化率各向异性（AMS）进行各向异性分析获得的磁性织物被用作岩石（流动）织物的代理。较厚的堤坝中心部分（走向垂直厚度> 10 m）的样品显示出磁性织物的随机性和不一致性发展要比其边缘相似性高。岩相学表明，仅在厚堤的边缘，才出现了细长矿物晶粒的相对清晰的形状优先取向。较薄的堤坝（垂向垂直厚度<10 m）显示出一致的磁性织物和清晰的形状优先方向。我们认为，厚堤的中心不能提供（由于高流速，较慢的冷却速度，缺乏摩擦引起的剪切作用以及岩浆回流）的有利条件，其中（a）流动织物可以有效地发育，并且（ b）磁性织物可以有效地模仿流动织物。因此，较薄的堤坝和较厚的堤坝的边缘是观察以磁性织物为代表的流动织物的更好的候选者。这项工作还受到早期研究人员在使用AMS技术进行岩浆流特征化（特别是对于大型堤防群）中表达的保留意见的鼓舞。我们已根据我们的结果严格评估了他们的保留意见，并评论了AMS技术在此类研究中的适用性。