Essay about The Volcanic Rocks

1355 Words Jun 8th, 2015 6 Pages
The eastern-most modeled section, C-C’, comprises the volcanic stratigraphy of the OB and the OIS. At the stratigraphic top of the volcanic pile is a modeled source of -0.034 SI that likely represents undifferentiated volcaniclastic rocks. Below these rocks are magnetic source bodies similar in magnetic susceptibility to other massive sulfide deposits and iron formation modeled A-A’ and B-B’. The more magnetic of these positively magnetized source bodies likely represents stacked iron-rich lenses, and the overlying lower SI body (0.0009) likely represents a weakly altered transitional rock body in-between the negatively polarized undifferentiated volcaniclastic rocks and the stacked iron rich lenses. A wedge of modeled intermediate to mafic volcaniclastic rocks with a magnetic susceptibility -0.0017 SI underlie the magnetic source bodies and are in turn underlain by the OIS. The OIS in C-C’ is modeled with six magnetically distinct source bodies. These source bodies range in magnetic susceptibility from 0.0045 to 0.0165 SI, and alternate between higher and lower magnetic susceptibilities. These modeled sources suggest the OIS is compositionally layered. Underlying the OIS is a package of negatively polarized rocks that range in magnetic susceptibility from -.0044 to -0.0017 SI. These values are consistent with mafic volcaniclastic rocks modeled in A-A’ and B-B’. Internally, this package of rocks shows heterogeneity and comparative thin magnetic highs (-0.0031 SI) that may…

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