In the sprawling domain of Earth sciences, the recent commentary by Basavaiah, Satyanarayana, and Prasad challenges and enriches the ongoing discourse on the magnetic fabric characteristics of the west coast dyke swarm within the vast Deccan Volcanic Province (DVP). This development follows the original work produced by Lakshmi et al., published in Environmental Earth Sciences in August 2024, which itself ignited considerable interest regarding the petrofabric and paleomagnetic attributes of one of the most extensive flood basalt provinces on Earth. The Deccan Traps, well-known for their geological complexity and emplacement history, continue to present puzzles that demand meticulous review and reinterpretation of magnetic data, and this commentary boldly ventures into those waters.
The study of magnetic fabrics in mafic dykes is pivotal because they encode critical information about the emplacement mechanisms, flow directions of magma, and tectono-magmatic processes. Lakshmi et al.’s original paper purported to identify specific primary magnetic fabrics that document magma flow directions within the swarms along the western margin of the DVP. Their interpretations, grounded in anisotropy of magnetic susceptibility (AMS) analyses, aimed to reconstruct flow dynamics and thereby provide insight into the stress regimes prevailing during dyke intrusion. However, the commentary by Basavaiah and colleagues brings to the fore nuances and potential oversimplifications in these interpretations, advocating a more nuanced understanding of the magnetic fabric records that could significantly alter geological reconstructions.
At the heart of this scientific dialogue lies the method of anisotropy of magnetic susceptibility, which unlocks a three-dimensional tensor of susceptibility values in rocks, essentially reflecting the preferred orientation of ferromagnetic minerals that align during rock formation. An accurate derivation of magma flow direction from these fabrics depends heavily on a careful differentiation between primary flow-related fabrics and secondary deformation fabrics resulting from tectonic overprints or alteration processes. Basavaiah et al. underscore that Lakshmi et al.’s approach may have conflated these factors, potentially mistaking tectonic flattening or post-emplacement reorientation for primary magmatic signals.
One key technical critique is the selection of magnetic mineralogy proxies used to interpret AMS fabrics. The magnetic behavior of titanomagnetite and other ferromagnetic minerals can vary widely under low-temperature oxidation or hydrothermal alteration, common in flood basalt provinces after emplacement. Basavaiah and colleagues argue that without comprehensive thermal demagnetization and mineralogical reassessment, AMS fabrics could be misleading. This standpoint is supported by detailed laboratory remanence experiments, which suggest that remanent magnetization directions and susceptibility ellipsoids may diverge significantly depending on mineralogical changes during cooling or weathering.
Furthermore, the commentary delves deeper into the important role of strain partitioning within dyke swarms. While Lakshmi et al. attributed observed fabric orientations predominantly to magmatic flow, Basavaiah et al. suggest that tectonic strain, especially in a region like the western margin of the DVP subject to extensional and transtensional stresses, can strongly overprint initial fabric signatures. These overprints may lead to complexities in anisotropy ellipsoid shapes which, if not correctly deciphered, could mislead interpretations about magmatic dynamics and regional tectonics.
Such nuances carry profound implications for geodynamic modeling of the Deccan volcanic event, often linked to mantle plume activity and volatile release episodes coincident with the Cretaceous-Paleogene boundary. The precise understanding of dyke emplacement directions and stress fields contributes to models estimating magma flow rates, plumbing system architectures, and interplay between volcanic events and surface processes. By contesting the straightforward flow interpretations, Basavaiah and colleagues implicitly call for an integrated multi-disciplinary approach combining AMS with petrological, geochemical, and structural datasets to unravel these complexities.
This commentary brings attention to the ongoing challenge of interpreting magnetic fabrics in volcanic provinces with complex emplacement and post-emplacement histories. It highlights potential pitfalls in the reliance upon simplistic AMS interpretations without sufficient corroborative evidence from other structural and mineralogical data. Such caution is crucial, given that misinterpreting magnetic fabric data can propagate through broader geological narratives, affecting tectonic reconstructions, hazard assessments, and our understanding of volcanic processes.
Moreover, the dialogue embodies a broader scientific principle: the iterative nature of research, where initial hypotheses undergo refinement or revision as new methods, data, or perspectives emerge. The exchange between Lakshmi et al. and Basavaiah et al. exemplifies the constructive debate necessary in a healthy scientific community, fostering deeper investigations and eventually leading to consensus or novel insights.
In the unfolding narrative of Earth’s magmatic provinces, the Deccan Traps remain an alluring yet challenging subject of study. The dykes composing the swarm dissect pre-existing crustal units and serve as records of past mantle melting episodes and crustal stress states. This commentary effectively urges the scientific community to reexamine prior AMS interpretations by incorporating stringent criteria that differentiate between magmatic and tectonic signals in magnetic fabrics.
In addition to AMS, advanced techniques such as electron backscatter diffraction (EBSD) and X-ray computed tomography are increasingly significant in resolving the microstructural fabrics of dykes. These methods can reveal mineral alignment at grain scales, enabling more precise reconstructions of deformation histories. While not addressed directly in this commentary, their potential inclusion in the ongoing discourse promises a more holistic understanding of the magnetic fabric and emplacement mechanisms.
In synthesizing the commentary’s key arguments, it is evident that geological interpretations in such a vast and complex volcanic system require meticulous consideration of both primary magmatic processes and secondary tectonic modifications. Basavaiah, Satyanarayana, and Prasad’s commentary advocates a reinterpretation of AMS data not as evidence of simple flow directions but as complex tapestries woven from multiple geological processes, urging a paradigm shift in how magnetic fabrics in the DVP and similar provinces are perceived.
The dialogue also raises interesting questions about the implications for regional tectonics. If the magnetic fabrics reflect substantial post-emplacement deformation, this suggests a more dynamic post-volcanic history than previously considered, potentially affecting models of crustal block rotations, fault activity, and seismic hazard assessments along India’s western margin.
For researchers hungry for a more accurate gauge of flow patterns within ancient volcanic provinces, the message is clear: magnetic fabric studies must be approached with a multi-pronged analytical arsenal and a critical eye toward interpreting susceptibility anisotropies within their broader geological contexts. This rigorous approach not only refines local rock fabric interpretations but also enhances the resolution of global magmatic and tectonic models.
The debate catalyzed by this commentary exemplifies the vibrant churning of ideas that propels Earth sciences forward. It prompts a reconsideration of magnetic fabric studies across comparable flood basalt provinces worldwide, including the Siberian Traps, the Paraná-Etendeka province, and the Columbia River Basalt Group, where similar complexities in interpreting AMS fabric data exist.
In conclusion, this scientifically robust commentary by Basavaiah et al. reaffirms the indispensable need for continued critical assessment of magnetic fabric data in the Deccan Volcanic Province and analogous geological settings. By challenging assumptions and emphasizing methodological rigor, it paves the way for more accurate reconstructions of magmatic and tectonic histories that are essential for unraveling Earth’s dynamic evolution.
Subject of Research: Magnetic fabrics and magma flow dynamics of the west coast dyke swarm from the Deccan Volcanic Province
Article Title: Comments on ‘Magnetic fabrics of west coast dyke swarm from Deccan Volcanic Province’ by Lakshmi et al.
Article References:
Basavaiah, N., Satyanarayana, K.V.V. & Prasad, J.N. Comments on ‘Magnetic fabrics of west coast dyke swarm from Deccan Volcanic Province’ by Lakshmi et al. (Environ. Earth Sci. 83, 465, August 2024).
Environ Earth Sci 84, 363 (2025). https://doi.org/10.1007/s12665-025-12372-4
Image Credits: AI Generated
