Chemical sedimentation associated with mid-Paleozoic volcanism in central Newfoundland

Swinden, H. S. (1976) Chemical sedimentation associated with mid-Paleozoic volcanism in central Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

Chert, ferruginous chert and associated chemical sedimentary rocks are a ubiquitous although volumetrically minor component of the Upper Ordovician-Silurian volcanic succession in Central Newfoundland. They are intimately associated with volcanic lithologies ranging from mafic pillow lava and pillow breccia to silicic flows and pyroclastic rocks, and occur both as thin, discontinuous bedded lenses conformable with the volcanic stratigraphy and as massive pods interstitial to mafic pillows. Although most units appear to be unrelated to base metal mineralization, a laterally continuous horizon at Gull Pond, the Gullbridge ferruginous chert, overlies and is spatially related to two volcanogenic copper deposits. -- Two hundred and forty-seven rock samples were analyzed for 10 major an 10 trace elements in order to examine inter-element relationships providing information on the genesis of these sediments and to determine whether chemical concentrations in the Gullbridge ferruginous chert could be developed as a useful exploration tool. -- Chemical data suggest that three processes contributed to the formation of these chemical sediments, viz; biogenic processes are inferred to have been responsible for most of the silica which is dominantly present as non-detrital quarts; hydrothermal processes are inferred to have contributed most of the Fe₂O₃, MnO, Ba, and Au; volcaniclastic sedimentation is the probable source of the remaining major and trace elements. Chemical trends in the rocks are strongly influenced by their mineralogy and can usually be related to the presence of specific minerals or groups of minerals.

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