New Zealand Journal of Geology and Geophysics abstracts

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Hydrogeological implications of geology at the boundary of Banks Peninsula volcanic rock aquifers and Canterbury Plains fluvial gravel aquifers

L. J. BROWN

Institute of Geological and Nuclear Sciences Ltd
P.O. Box 30 368
Lower Hutt, New Zealand

J. H. WEEBER

Canterbury Regional Council
P.O. Box 345
Christchurch, New Zealand

Abstract  Two aquifer systems abut at the coastal northern Canterbury Plains adjacent to Banks Peninsula. These are: (1) the northern Canterbury Plains coastal, confined, upper Quaternary, fluvial gravel aquifers, with groundwater recharge derived from influent seepage from the bed of the Waimakariri River to the northwest of Christchurch; and (2) the Banks Peninsula aquifers, with groundwater in fractures, joints, and fissures in the Miocene volcanic rock. Data including well logs, water level and temperature measurements, and chemical and isotope (tritium and oxygen 18) analyses show that groundwater from volcanic rock aquifers is derived predominantly from Banks Peninsula precipitation--but there is also mixing with Canterbury Plains groundwater derived from the Waimakariri River. Flow paths are complex, and basement faulting may facilitate mixing and warming of groundwater.

Keywords  Banks Peninsula; Canterbury Plains; Lyttelton Harbour; Christchurch; Heathcote Valley; groundwater; groundwater chemistry; saltwater intrusion; mineral water; thermal water; hydrogeology; Quaternary; Holocene; Lyttelton Group Volcanics; Riccarton Gravel

PDF file of entire paper: medium quality (1390K); (scanned from paper original: notes about this process)

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