Minutes book of the Fermanagh Association, 1974-1980

A hardback notebook containing handwritten records of the Association's meetings. Pages not reproduced here are blank

Dynamic redox and nutrient cycling response to climate forcing in the Mesoproterozoic ocean

Controls on Mesoproterozoic ocean redox heterogeneity, and links to nutrient cycling and oxygenation feedbacks, remain poorly resolved. Here, we report ocean redox and phosphorus cycling across two high-resolution sections from the ~1.4 Ga Xiamaling Formation, North China Craton. In the lower section, fluctuations in trade wind intensity regulated the spatial extent of a ferruginous oxygen minimum zone, promoting phosphorus drawdown and persistent oligotrophic conditions. In the upper section, high but variable continental chemical weathering rates led to periodic fluctuations between highly and weakly euxinic conditions, promoting phosphorus recycling and persistent eutrophication. Biogeochemical modeling demonstrates how changes in geographical location relative to global atmospheric circulation cells could have driven these temporal changes in regional ocean biogeochemistry. Our approach suggests that much of the ocean redox heterogeneity apparent in the Mesoproterozoic record can be explained by climate forcing at individual locations, rather than specific events or step-changes in global oceanic redox conditions

Gas geochemistry: From conventional to unconventional domains

Gas geochemistry is developing into a powerful tool to understand geological processes and affirm source origins of geo-fluids. Major and trace gases, including abundances and isotopes, have shown considerable application in natural gas systems. For example, progress in unconventional gases such as shale gas, tight gas, and extreme conditions in the deep oceans represent more emerging areas and application of these novel gas-related techniques. Examples where gas geochemistry continues to place key constraints on the origin and migration characteristics of natural gas, the P-T characteristics of fluids in both subaerial and deep geothermal reservoirs, and the dynamics of the accumulation cycles, to name but a few. This volume will reflect this diversity in scope and application of gas geochemistry, focusing on deeper and broader applications in unconventional domains of novel gas geochemical techniques and applications

Geological features and formation of coal-formed tight sandstone gas pools in China: Cases from Upper Paleozoic gas pools, Ordos Basin and Xujiahe Formation gas pools, Sichuan Basin

The distribution of coal gas pools is controlled by many geological factors in China. The accumulation and pool-forming process of coal measures gas is studied from aspects of structure, source rock evolution, reservoir, pool-forming history, etc. The comparison results show that there are many similarities in geology between the Upper Paleozoic gas pools in Ordos Basin and the Upper Triassic Xujiahe Formation gas pools in Sichuan Basin, and the difference of the gas pools features in the two basins is caused by different structural evolutions and pool-forming processes. In Ordos Basin, water shoved by gas migrated from lower to higher positions in the formation process of the gas pools, and the abnormality of low gas reservoir pressure was caused by the water and gas reversal. In Sichuan Basin, structural traps controlled the gas pools distribution in Xujiahe Formation, lithologic gas pools was found locally, and the main factors for the abnormally high pressure are the undercompaction due to quick deposition, the hydrocarbon generation of source rocks and the structural compression during the Himalayan period. Key words: coal-formed gas, Ordos Basin, Sichuan Basin, Upper Paleozoic, Xujiahe Formation, pool-forming histor