Dissertations, Theses, and Capstone Projects
Date of Degree
2-2026
Document Type
Doctoral Dissertation
Degree Name
Doctor of Philosophy
Program
Earth & Environmental Sciences
Advisor
Benjamin A. Black
Committee Members
Marc-Antoine Longpré
Karin A. Block
Loÿc Vanderkluysen
Subject Categories
Volcanology
Keywords
Deccan Traps, carbon budget, volatiles, mantle sources, olivine timescales
Abstract
Large Igneous Provinces (LIPs) are voluminous intraplate magmatic events thought to originate from a variety of tectonic events including mantle plumes (Campbell & Griffiths, 1990; Richards et al., 1989), separation of continents (Courtillot et al., 1999) and delamination of the mantle lithosphere (Tanton & Hager, 2000). LIPs have been associated with major climate and carbon disruptions in Earth’s history (Wignall, 2001; Clapham and Renne, 2019) and also coincide temporally with mass extinction events (Courtillot & Renne, 2003; Wignall, 2001). Geochronology studies constrain the bulk of LIP emplacement to within one million years and magnetostratigraphy independently supports this finding and suggests that LIPs are emplaced in cycles of heightened magmatic activity lasting decades.
In this work we investigate the Deccan Traps Large Igneous Province and its connection to the Cretaceous-Paleogene (K-Pg) mass extinction event that wiped out many land and ocean species including the dinosaurs, as reviewed in Chapter 1. The emplacement of the Deccan Traps largely occurred between 66.5 and 65.5 Ma, and emplaced up to 2 x 106 km3 of lava (Jay and Widdowson, 2008). However, the true subaerial volume of LIPs difficult to constrain in part because of weathering and erosion (Schoene et al., 2021). The main stage of Deccan Traps magmatism is represented by a sequence of lava flows of up to 2 km in thickness known as the Western Ghats. The composition of this lava sequence is mostly tholeiitic in composition. To the northwest, in the Saurashtra peninsula, highly forsteritic rocks including picrites can be found (Krishnamurthy, 1974; Beane et al., 1986; Beane, 1988; Peng and Mahoney, 1995).
In Chapter 2, we investigate a 2-4 °C warming episode, known as the Latest Maastrichtian warming event (LMWE). The LMWE preceded the Cretaceous-Paleogene boundary (KPB) mass extinction at 66.05 ± 0.08 Ma and has been linked with the onset of voluminous Deccan Traps volcanism. We tested the hypothesis that Deccan magmatism triggered the LMWE. To do this, we directly measured CO2 concentrations of melt inclusions and made estimates of CO2 based on trace element proxies for CO2. We found that volcanic CO2 outgassing alone cannot account for the magnitude of the observed latest Maastrichtian warming. However, accounting for intrusive outgassing can reconcile early carbon-rich Deccan Traps outgassing with observed changes in climate and atmospheric pCO2 during the LMWE.
In Chapter 3, we attempt to place better constraints on the volatile budget and sources of Deccan magmas. This in turn will allow us to assess the environmental response due to volatile release from Deccan magmatism. The temporal connection between Large Igneous Provinces and mass extinction events has been suggested because LIPs release volatiles (CO2, SO2, F and Cl) that can exert a global impact on Earth’s systems. Therefore, constraining the source and budget of each volatile is needed to understand the potential environmental consequences of volcanic volatile release. LIP melts originate from a heterogeneous mantle with a variety of contributing sources (e.g., mantle plume, asthenosphere, lithosphere, and crust). We report volatile and trace element concentrations of two melt inclusion suites hosted in picritic and highly magnesian lavas from the Saurashtra province in northwestern Deccan and from the Thakurvadi Formation in the main sequence of Deccan volcanism. We combine our data with published constraints on Deccan volatiles to show that F, S, and Cl evolve in distinct fashions. We find that volatiles in LIP magmas are controlled by a complex suite of factors including mantle source, pressures and temperatures of melting, and incorporation of lithospheric mantle and crust. We show that Deccan magmas had similar H2O/Ce, and Cl/K to global melt inclusion suites. However, Deccan magmas seem to have substantially higher F/Nd ratios. We attribute this elevated F/Nd to incorporation of an ancient lithospheric mantle, which may be a major reservoir for F.
In Chapter 4, we investigate the magmatic history of individual Deccan Traps lava eruptions using Fe-Mg diffusion chronometry in olivines. Fe-Mg zonation of olivine crystals is suited to understand the timescales and eruption dynamics of individual eruptions because diffusion timescales for Fe-Mg exchange in olivine are similar to timescales of magma ascent and eruption. Olivine zonation has revealed recharge events prior to eruptions at a range of tectonic settings, but this technique has not been extensively applied to LIPs. Here, we use picrites from northwestern Deccan lavas representing early stages of magmatism and Thakurvadi Formation olivines representing the main stage of Deccan magmatism. We find that Saurashtra crystals tend to show substantially steeper zoning profiles compared with Thakurvadi crystals, consistent with more rapid mixing-to-emplacement timescales. However, interpretation is complicated by the lack of information about lava emplacement timescales. We compare Deccan Traps olivine diffusion profiles with those of more recent basaltic eruptions, and find overall similarities, suggesting that Deccan Traps magmatic processes broadly resemble those occurring in smaller-scale basaltic systems.
Recommended Citation
Hernandez Nava, Andres, "One Olivine Crystal at a Time: Unraveling the Volatile Budget and Timescales of the Deccan Traps Large Igneous Province" (2026). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/6586
