METACONGLOMERATE

 

Metaconglomerates are conglomerates that have been metamorphosed.  The rocks shown below are called “Black Marinace Gold Granite”, “Marinace Green Granite”, and “Marinace Red Granite”, but they are anything but granite.  These are polymict metaconglomerates (polymict means composed of pebbles/cobbles of several different rock types).  Metamorphism has altered the original conglomerate, but the clast shapes & lithologies are still fairly well preserved.

 


 

Black Marinace Gold Granite (sometimes considered “Black Mosaic Granite”; also apparently (?) known as “Black Morgan Granite”) - a very attractive Precambrian polymict metaconglomerate from Brazil with small-scale interpenetrating pressure-solution contacts between clasts in many areas (see lower right, upper central-left, upper central-right).

 


 

 

Marinace Green Granite - a greenish, Precambrian-aged, polymict metaconglomerate from Bahia State in eastern Brazil.  Available clast lithology compilations indicate that this rock is dominated by pebbles & granules of granite, gneiss, and mafic igneous rocks.  Some clasts have been partially epidotized.  The matrix is a pleasant greenish color (dominated by epidote, quartz, and tremolite).

 


 

Marinace Red Granite - another Precambrian-aged polymict metaconglomerate from Brazil.  This rock has a nice dark reddish-colored matrix and clasts of variable size and composition (mostly igneous & metamorphic, plus relatively common epidotized clasts).  Other commercial names that appear to have been applied to the same rock include “Paladium Granite”, “Palladio Granite”, and “Palladio Vesuvio Granite”.

 


 

 

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