Abstract
Abstract: Earlier, whole-rock data assisted in constraining magmatic processes accountable for the evolution of Giant Plagioclase Basalt (GPB), although plagioclase chemistry data-based implications are rare and critical, while combining with bulk-rock chemistry to understand magmatic processes regionally. For this reason, giant and small-size plagioclase grains were analyzed using Electron Probe Microanalysis (EPMA). Core to margin of the Kalsubai Subgroup GPB grains show significant variation ranging from An99Ab1–An94Ab6 to An65Ab35–An5Ab95, respectively. Nucleation of An-rich core initiated in the mid-lithospheric level at elevated temperatures, varying between 1490 and 1510°C, but successive An-poor intermediate and marginal layers crystallized at low temperatures between 1200–1360°C and 910–930°C that also in shallower depth, respectively. Moreover, supercharged feldspar-rich magma persisted throughout the Kalsubai Subgroup lavas, as noticed by the absence of zoned plagioclase. Almost similar processes were followed, but in a subdued manner at 1220–1300°C temperature in the Kevlari–Kalan area that lies ~900 km apart in the eastern Deccan Volcanic Province (DVP). Presence of plume-fed magma chamber is also justified by the size and thickness of the Kalsubai Subgroup lavas. Uninterrupted recharge of magma source was continued as Ab/An value remains constant throughout the Kalsubai Subgroup lava sequence. Further, residence period of 3.2–17.4 ka is assigned to GPB of the Kalsubai Subgroup. Owing to high eruption rate, younger formations of the main DVP do not contain GPB, but Kevlari Kalan GPB contains labradorite (An60Ab40–An50Ab50) rich plagioclase, crystallized during storage of the magma for a shorter interval comparing to Kalsubai Subgroup GPB lavas. Research Highlights: Giant plagioclase contains Ca- rich (An99) core and Ca-poor (An65) rimThree crystallization episodes assigned to Kalsubai GPB and one to Kevlari Kalan GPBOwing to high eruption rate, younger western DVP is devoid of GPB.
Original language | English |
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Article number | 172 |
Journal | Journal of Earth System Science |
Volume | 131 |
Issue number | 3 |
DOIs | |
State | Published - Sep 2022 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2022, Indian Academy of Sciences.
Keywords
- Deccan Volcanic Province (DVP)
- Giant Plagioclase Basalt (GPB)
- mineral chemistry
- residence time
- three episodes of crystallization