Tutor profile: Santiago S.
What can be interpreted from a crenulation fabric in a metamorphic rock?
Firstly, it is important to bear in mind that a crenulation fabric gets formed from an existing foliation and its formation is related to the superposition of a different stress field over the rock. Having said that, a crenulation fabric could be interpreted as retrogressive metamorphism (exhumation), if the crenulation was formed together with low temperature and pressure minerals. On the other hand, a crenulation fabric could also mean a progressive state of deformation with only the stress field changing over time, this could be interpreted only if the same mineralogy is observed in both, the first foliation and the crenulation.
What ore deposits formed in subduction environments?
Most of the common ore deposits formed in subduction environments are Cu-Mo Porphiries, Cu (Ag-Au) Porphiries, Epithermal deposits (low, medium, high sulfuration), intrusion-related, IOCG, VMS (Back-arc environments and intra-arc environment), and Skarm deposits.
Subject: Earth Science
What aspects controlling the geochemical features of igneous rocks?
The geochemical features of igneous rocks are the result of the interaction of several processes, such as the depth of melting, the components interacting during the melting (mantle, oceanic crust, continental crust, lithosphere), the degree of melting and the magma rising velocity. For instance, the depth of melting is directly related to the temperature, which means the greater the depth, the higher the temperature and also the amount of partial melting. Besides the temperature, the depth of melting also controls what components are going to melt (mantle, oceanic crust, continental crust, lithosphere), which would have a strong influence on the geochemical behavior of the igneous rocks (MORB, OIB, SDZ).
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