Farming practices within the upper Selwyn plains have significantly expanded, and are becoming more dependent on groundwater as a reliable source of irrigation. This expansion has resulted in the rapid development of the groundwater resource and water levels in many wells have reached record low levels. Groundwater resources can be found within at least three aquifers within the glacial gravel deposits of the upper Selwyn plains. Aquifer 1 occurs between approximately 0-30 m, aquifer 2 between 40-85 m and aquifer 3 greater than 100 m below the surface. Aquifers 1 and 2 occur within close proximity to the Selwyn River and its tributaries. Aquifer 1 is unconfined, aquifer 2 semi-confined and aquifer 3 semi-confined to confined. Significant leakage of groundwater occurs between the different aquifers. Recharge sources to the aquifers include rainfall infiltration and river seepage. Water levels and groundwater chemistry suggest that the Selwyn River provides the dominant source of recharge to aquifers 1 and 2 in areas immediately surrounding the river and to the south of the current course of the river between Greendale and Dunsandel.

No description available.

Devonian and Early Carboniferous marine clastic rocks of the Earn Group host several economically important stratiform massive sulphide and bedded barite deposits. Due to the chaotic sedimentation, considerable regional metamorphic overprint and, relative inaccessibility, little was known about the stratigraphy, the Late Devonian conodont fauna, or the age of the stratiform mineral deposits within the Earn Group. Conodont microfossils, however, are an excellent fauna for an Earn Group biostratigraphy program because of their ability to withstand both temperatures in excess of 400° C, and significant physical stress. With standard laboratory techniques conodonts were readily extracted from fine grain calcareous elastics and carbonate lenses within the Earn Group. The conodonts are described from three specific areas where the Earn Group is known to host stratiform barite and barite-lead-zinc mineral deposits: Macmillan Pass, Midway, and Gataga. As the majority of conodonts were diverse and well preserved platform elements of the genus Palmatolepis, the taxonomic studies focused on this genus; other genera including Ancyrodella, Icriodus, Klapperina, Mesotaxis, and Polygnathus were examined as part of the biostratigraphic/taxonomic studies. Previous to this study the widespread stratiform mineralization was dated as only Late Devonian. The conodont taxonomy and biostratigraphy in the Earn Group provide age constraints for duration and formation of the stratiform mineralization. The ability to tightly constrain the age of the stratiform mineralization adds to the knowledge of Earn Group deposition, the paleogeography of the Selwyn and Kechika Basins, and has implications for stratiform mineral exploration strategies in the Earn Group. On the basis of conodont faunal ages barite mineralization at MACMILLAN PASS apparently occurs as three different levels: 1) CATHY property - Eifelian to early Frasnian; 2) PETE, JEFF, GARY, and GHMS properties - middle to late Frasnian; 3) TEA property -Early Carboniferous. In addition, barite-lead-zinc mineralization at TOM and JASON properties likely occurs during middle to late Frasnian. In the GATAGA area barite and barite-lead-zinc mineralization have been recognized at several temporally distinct levels in the early to middle Famennian: 1) Lower rhomboidea Zone; 2) Lower marginifera Zone; 3) Upper marginifera Zone. Several other mineralized horizons are loosely constrained within the same interval. Within the MIDWAY area the stratiform barite mineralization at the EWEN and PERRY properties is of Early Carboniferous, Tournaisian age, and correlates broadly with the TEA barite in the Macmillan Pass area. In summary, events that produced stratiform barite-lead-zinc and barite mineralization in the Selwyn and Kechika Basins were not coeval. The Late Givetian and early Frasnian barite mineralization took place in the Macmillan Pass and southernmost Gataga areas. During the middle Frasnian barite and barite-lead zinc mineralization events occurred at Macmillan Pass. Several episodes of barite and/or barite-lead-zinc mineralization occurred in the Gataga area during the middle Famennian. The youngest barite mineralization events in the Earn Group took place in the Early Carboniferous, Tournaisian time at Macmillan Pass and Midway. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

<p> The BAR CLAIM GROUP is located on the western margin of the Selwyn Basin geologic province in south central Yukon. The rock sequence is eugeosynclinal in nature, belonging to the Englishman's Group of the Mississippian. Chronologically, these rocks include massive limestone, white to red chert breccia, dark grey chert breccia, chert pebble conglomerate, lithic wacke, massive barite, grey green chert, and hornblende microdiorite. The elastic units in particular appear to be correlative with the units on the eastern margin of the Selwyn Basin. </p> <p> The barite is light grey, bedded, massive, and contains rare relic rosette structures. Associated minerals include pyrite, galena and minor sphalerite. Extensive recrystallisation and mobilization has occurred, probably as a result of regional compression and faulting. The barite may have had an exhalative origin along fault or extensional zones; however, sedimentogenic sources, such as the redistribution of pre-existing barite, cannot be precluded. </p> / Thesis / Bachelor of Science (BSc)