Chloritization and carbonatization of Cambrian volcanic rocks in eastern Newfoundland and southern New Brunswick, Canada

Abstract

Cambrian basaltic flows and volcaniclastic rocks on the Avalon Peninsula of Newfoundland and from the Beaver Harbour area of southern New Brunswick show two phases of alteration which resulted in the formation of chlorite and carbonate in most of the rocks. Calculations which account for volume changes show that chlorite-forming reactions resulted in the addition of Mg, Sr, P and Mn and the removal of K, Rb, Ti, Zr, V and Fe from the Beaver Harbour rocks whereas Ca, Sr, Ba, Rb and K were removed and Ni, Cr, Ga, V and Mn added to Avalon samples. These results resemble those produced by basalt-seawater interaction, particularly in the Beaver Harbour case where Mg increases. In the Beaver Harbour rocks carbonate metasomatic reactions led to the addition of Ca, Sr, Na, Mg, P, Y and Zn and removal of Ba, Rb and K in proportion to the amount of carbonate added. Ca, Na, Sr and CO 2 were added and Mg removed in the Avalon rocks. With the exception of Mg removal (Avalon), the behaviour of most elements from both localities resembles that observed in systems with high CO 2 activity. The increase of P and Y in the Beaver Harbour rocks indicates F may have also been an important constituent of metasomatic fluids.