Date of Graduation
Eberly College of Arts and Sciences
Geology and Geography
Kathleen C Benison
The Carnduff 2 core, drilled in 2014 by the Gaelectric Storage Limited Energy Company in County Antrim, Northern Ireland contains Triassic red mudstones and evaporites of the Mercia Mudstone Group. These rocks have been poorly studied in Northern Ireland. However, recent work suggests that they were deposited in an ancient perennial saline lake system. This thesis describes a 591.6 meter core with 92.7% recovery. Fluid inclusion petrography, microthermometry, and laser Raman spectroscopy were conducted on 12 halite beds of the Larne Halite Member to characterize Triassic lake waters.;Chevron and cumulate halite crystals contain abundant unaltered primary fluid inclusions. Most primary fluid inclusions are all liquid, but there are also fluid inclusions that contain daughter crystals. Petrographic studies showed that primary inclusions have a double rim. This double rim is not seen on fluid inclusions with neutral pH. This suggests that double rims may be a new criterion for determining acidity. Fluid inclusions failed to freeze during freezing-melting microthermometry, even after being exposed to -190º C for several minutes. The failure to freeze during microthermometry runs is likely due to low pH and/or extremely high salinity. Laser Raman spectroscopy of 45 inclusions showed peaks for bisulfate and/or aluminum sulfate compounds in 10 of the 12 beds, indicating high sulfate and aluminum in solution. More importantly, such peaks are characteristic of waters having pH values < ~3.;This study provides evidence for the first time that bedded halite of the Mercia Mudstone Group of Northern Ireland formed in acid, saline lakes. Additionally, new criteria for determining low pH in the rock record has been established. Finally, this study suggests that, when compared to Permian acid brine deposits of North America, the red beds and evaporites of the Triassic Mercia Mudstone Group of Northern Ireland may be part of spatially extensive and long-lasting, acid saline environments of Pangea.
Eichenlaub, Lynnette Ann, "A fluid inclusion study of acidity in bedded halite of the Larne Halite Member, Triassic Mercia Mudstone Group from the Carnduff 2 Core, County Antrim, Northern Ireland" (2016). Graduate Theses, Dissertations, and Problem Reports. 5532.