Applicability of AMS technique as a flow fabric indicator in dykes: insight from Nandurbar–Dhule Deccan dyke swarm

Banding in the Margins of Basaltic Dykes Indicates Pulsatory Propagation During Emplacement

“…The SPO of phenocrysts within the Teno sample shows no variation toward the dyke center, or within the bands themselves, suggesting that the flow direction for each pulse remained constant (Philpotts & Asher, 1994; Wada, 1992). The degree of SPO is highest closer to the margins, echoing the results of previous studies (Coward, 1980; Das & Mallik, 2020), and the reduction in the degree of preferred orientation toward the dyke center could be due to an increasing groundmass crystallinity within each subsequent pulse, increasing the prevalence of crystal collisions. However, the overall consistency in SPO between the bands suggests that pulses were not substantially different from one another in terms of their fluid dynamics.…”

“…It is therefore worth considering whether large‐scale layering within dykes may not arise from discrete magma pulses from the source, but from pulses generated within the dyke itself due to the influence of solidification. It is interesting to imagine the largest scale on which this behavior might occur; for example, whether centimetre‐to meter‐scale layering marked by internal chilled margins (e.g., Platten, 2000) or differences in columnar jointing structure (e.g., Das & Mallik, 2020; Gudmundsson, 1984; Ray et al., 2007) could result from large scale, internally generated, solidification‐driven magma pulses.…”

The Magmatic Architecture of Continental Flood Basalts I: Observations From the Deccan Traps

“…Without a detailed field analysis of individual flow fields along with complementary geochemical and isotopic analyses, each of these models may be applicable for Deccan eruptive episodes with potentially different styles for different DT regions, subprovinces, and/or geochemical formations. The four main DT dike swarms are the Narmada‐Tapi dike swarm extending across from Mandla Lobe region to Saurashtra (Bhattacharji et al., 1996; Cucciniello et al., 2015; Melluso et al., 1999; Ray et al., 2007; Sant & Karanth, 1990; Sheth et al., 2013, 2019), the Saurashtra dike swarm (Chatterjee & Bhattacharji, 2001: Cucciniello et al., 2020), the Western Ghats Coastal dike swarm (P. Hooper et al., 2010; Patel et al., 2020; Samant et al., 2019; Sheth et al., 2014; Widdowson et al., 2000), and the Central Dike Swarm (also called Nasik‐Pune dike swarm) located to the east of the WGE (N. Bondre et al., 2006; Das & Mallik, 2020; Ray et al., 2007; Vanderkluysen et al., 2011; See Figure 9). Based on similar major and minor element geochemistry as well as Pb‐Nd‐Sr isotopes, the three (excluding the Saurashtra swarm which feeds that corresponding sub‐province) major dike swarms have been correlated with individual geochemical formations across the Deccan Traps (e.g., Patel et al., 2020, and references therein; Vanderkluysen et al., 2011).…”