Abstract
This study focuses on empirical and mathematical approaches within thermodynamic framework to constrain the mineralogic, petrographic evolution, and magmatic conditions of the IC-10 sample within the flood basalt provinces. Field mapping and thin-section analyses with respect to empirical and mathematical approaches reveal the evolution of primary mantle melts as they ascend to the surface along an imposed pressure-temperature path which were estimated to be Hortonolite, Magnesioaugite, labradorite, and FeโTi oxides, consistent with typical tholeiitic basaltic compositions. Whole-rock geochemical, mineralogical and petrographic data classify the lavas as tholeiitic basaltic lava type characterized by high total alkali contents (NaโO + KโO ห3} with the modal olivine greater than 5% [Modal olivine ห5%]. Mineral-based geotherbaromometric calculations yield crystallization temperatures of 700โ900 ยฐC at P = 1 kbar, suggesting magma storage within the upper mantle to lower crustal levels. These results imply that the IC-10 within the flood basalt provinces evolved through fractional crystallization of lower-crustal high-velocity layers beneath oceanic plateaus and hotspot tracks represent fractionated cumulates from picritic mantle melts and are therefore an integral part of plume volcanism.The findings contribute to the broader understanding of volcanic activity of IC-10 within the flood basalt provinces and its geodynamic in line with the Cameroon Volcanic Line.
Keywords: Mathematical, Geology, Olivine, Petrographic, Geochemical.
1. Introduction
The analyses of basaltic rocks within flood basalt provinces [1] affected by plume volcanism require an understanding of the geodynamic and petrologic processes associated with partial melting of mantle plumes using mathematical and empirical approaches. Plumes of hot material rising from the Earthโs mantle are believed to be caused by intraplate volcanic hotspots [2]. It is most likely that continental flood basalts and oceanic plateaus were formed by enhanced melting of a large plume head at the initiation of mantle plume activity. Geochemical analyses of flood basalts within mathematical and empirical frameworks provide constraints on the depth of original melting for plume magmatism, and often indicate that garnetbearing peridotite could be from a magma source. Hawaii is said to be a garnet bearing source [6], also for the Siberian Traps [7], and for the Wrangellia Terrane [S], which are probably accreted fragment of an oceanic plateau [9]. The interaction of plumelithosphere shows that melting of the lithosphere is considerate by using Thermomechanical models and that the bulk of the parent magmas are produced within the mantle plume [l0,1 1]. The estimated melting depth of 70-120 km (i.e., 20-40 kbar pressure) is within the stability field of garnet peridotite. According to petrological models within the context of mathematical and empirical approaches as well as melting experiments on mantle lherzolite in this pressure range, the composition of the liquid is picritic, with high MgO content (15-18 wt%). Although picrites occur in provinces affected by plume magmatism, the largest volumes of volcanic rocks are tholeiitic basalts, with a fairly constant MgO concentration (6-8 wt%). The conclusion that erupted lavas do not represent primary magmas, but are instead largely derived via crystal fractionation, has important implications for crustal evolution [ 12]. There is now a growing body of seismic data that allow imaging of the deep crustal structure of hotspot tracks, such as Hawaii [13] and the Marquesas Is- lands [14], of oceanic plateaus, such as Ontong Java [15], and of continental flood basalt provinces, such as the Columbia River Plateau
2. Results
The basaltic rocks of flood basalt provinces are classified using their major oxide compositions and these are shown in Tables 1, below. The SiOโ contents range between 45.8โ52.4 wt %, while total alkalis (NaโO + KโO) vary from 3.1โ5.7 wt %, indicating a mildly alkaline character. The FeโOโ/MgO ratios (1.6โ2.3) and TiOโ > 1 wt % further suggest a transitional to alkaline affinity, typical of basaltic rock of flood basalt provinces. The classification aligns with the tholeiiticโalkaline basalt spectrum of Yoder and Tilley (1962) and corresponds to basaltic magmas derived from a heterogeneous upper-mantle source that experienced limited fractional crystallization prior to eruption
3. Conclusion
The flood basalt provinces are a products of mantle-derived, mildly alkaline basaltic magmatism, emplaced along reactivated basement fractures. We used the mathematical and empirical approaches [19] to model the compositional evolution of deep mantle plume melts [17], assuming that crystal fractionation is the dominant mechanism through which picritic liquids evolve toward a basaltic composition and the minerals estimated were Hyalosiderite (Fo57), Magnesio-augite, and Labradorite (An67). The rock type is tholeiitic basalt and the magma type is tholeiitic basaltic magma Type because the modal olivine is less than 5%
References
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