A lithogeochemical study of the host rocks of the Strickland Showing

• Main Author: Wynne, Paula Jane
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1983
• Subjects: Silver Hill; Newfoundland
• Online Access: https://research.library.mun.ca/6825/; https://research.library.mun.ca/6825/1/PaulaJaneWynne.pdf; https://research.library.mun.ca/6825/3/PaulaJaneWynne.pdf

The Strickland showing consists of several zones of Zn-Pb-Cu-Ag mineralization hosted in a sequence of volcanic, volcaniclastic and sedimentary rocks which form a coherent belt stretching for 100 km along the south coast of Newfoundland. The sequence has been metamorphosed to upper greenschist facies and subjected to inhomogeneous cataclastic deformation. The mineralization identified in five principle zones (Main, Bog, Silver Hill, Copper and Carrot Brook) is interpreted to have been emplaced synvolcanically. This investigation is concerned with the identification of lithogeochemical signatures in the host rocks, produced by the mineralizing events. -- A total of 294 surface and 292 diamond drill core samples were collected in the Strickland area. They were analyzed for SiO₂, TiO₂, Al₂O₃, FeO, MnO, MgO, CaO, K₂O, Na₂O, P₂O₅ and LOI (loss on ignition). Most were also analysed for Cu, Pb, Zn and Ag and a selected number of surface samples for Zn, Sr, Rb, U, Th, Ga and Y. -- Two statistical approaches were taken in which regression techniques were used to generate residual values for elements in an effort to remove the effects of the rocks' primary composition, i.e. to define anomalies related to mineralization irrespective of lithology. In the first approach discriminant analysis showed that the elements TiO₂, Al₂O₃ and FeO contributed most to the discrimination between lithologies. These elements were then used as independent variables in curvilinear regression equations with which residual values were calculated. A second more refined approach was taken where the data were divided into three groups based on lithology, (igneous, sedimentary and mixed) and TiO₂ (an index of differentiation) was used as the independent variable in curvilinear regression equations to generate residuals for the igneous and mixed groups. Anomalous residual values combined with anomalous analyses from the sedimentary group are referred to as the second pass anomalies. These were found to be more effective in identifying anomalous ...