Crystallization Processes and the Geochemical Journey of Mg

Ever wondered how a single molten magma evolves into rocks of strikingly different compositions?
This presentation explores the fascinating geochemical journey of Magnesium (Mg) through various crystallisation processes, including batch/equilibrium crystallisation, fractional crystallisation, partial melting, magma mixing, and crustal assimilation.
Discover how Mg behaves as a compatible element, shaping the mineralogy and chemistry of magmatic systems from the mantle to the crust. Perfect for geology and geochemistry enthusiasts, students, and researchers seeking to understand magmatic differentiation in a clear and visually engaging way.
***Ideal for Earth Science students preparing for academic references, presentations, or competitive exams like CSIR-NET, GATE, and JAM.

1. Crystallization Processes and the Geochemical Journey of Mg in Magma Presented by Deep Gupta

2. Magmatic differentiation  Magmatic differentiation is the process where a single magma evolves into multiple magmas of different compositions through various processes, including crystallization .  As magma cools, minerals begin to crystallize from the liquid phase, and the composition of the remaining liquid changes, leading to different magma types. 

3. Batch/ Equilibrium Crystallization Crystals form from a cooling melt in a closed system (i.e., no eruptions of magma out of the system or injections of fresh melt into the system). Chemical equilibrium is maintained until the melt has completely crystallized. C L /C O = 1/[K D (1-F)+F ], where = fraction of melt remained after crystallization S eparation of crystal instantaneously as it is formed(e.g., by settling to the bottom or floating to the top of a magma chamber). only instantaneous equilibrium between solid and liquid. C L /C O = F (K D -1 ) , Where, F = fraction of melt remained after removal of crystals from melt Fractional Crystallization (here, C L = Concentration of element in liquid, C O = Concentration of element in original rock, K D = bulk coefficient)

4. Behaviour of Mg throughout the evolution of Magma It is a key major element ( >1 wt. %) in magmatic process. It is a compatible element (D >1) that has crucial role in early stages of magmatic crystallization. In its geochemical evolution, it governed by various processes like partial melting, fractional crystallization, magma mixing and assimilation. High MgO content Mg originates primarily from Mantle Partial Melting preferentially extracts incompatible elements low degree of PM = lower MgO content high degree of PM = higher MgO content PRIMITIVE MAGMA

5. Behaviour of Mg throughout the evolution of Magma Fractional Crystallization Magma cools Mg rich minerals will crystallize early these minerals remove from the system decrease in MgO content Melt rich in Si Evolved Magma Magma mixing mixing of primitive and evolved magma MgO content increase

6. Behaviour of Mg throughout the evolution of Magma Crustal Assimilation MgO again decreases SiO2 increases Due to these dynamic processes ( fractional crystallisation, magma mixing and Assimilation), magma system keeps evolving THANK YOU ......