Txt data from authigenic K-feldspar : an integrated methodology for constraining fluid flow

• Main Author: Mark, Darren Francis
• Published: University of Aberdeen 2009
• Subjects: 552; Feldspar
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499645

The timing and duration of fluid flow through sedimentary basins is paramount to understanding basin evolution.  Episodes of fluid flow often deposit authigenic (low temperature) minerals around detrital grains and can result in the concentration of metalliferous deposits and hydrocarbons.  Although numerous studies have dated the growth of authigenic mineral phases in an attempt to date fluid flow, these studies have not been able to determine the properties of the fluids from which the minerals grew.  A new approach is therefore required which is capable of determining the temperature, salinity and composition of palaeo-fluids as well as resolving the timing and duration of fluid flow. Through analysis of authigenic K-feldspar cements using fluid inclusion petrography and microthermometry in conjunction with high-resolution UVLAMP Ar-Ar dating, this study has developed an integrated methodology capable of determining the parameters described above.  The methodology is outlined and through using core samples from the UK Atlantic Margin, the methodology was tested in a geologically complex area that has experienced several phases of rifting, basin-scale fluid flushing, magnetic intrusion and volcanic activity. The methodology was subsequently tested throughout the UK sector of the 480 Ma Laurentian Margin, a complex margin that has witnessed several phases of successive orogenesis. Although not intended as a definitive study of Ar-diffusion within authigenic K-feldspar, this research does provide a valuable data set from which discussion can begin.  Meaningful Ar-Ar ages were determined from authigenic K-feldspar which displays a subgrain microtexture.