QA_Vol 24_No 1_July 2007 - Australasian Quaternary Association

Research ArticleA Reconnaissance Study of Glaciation on theOwen Massif, Northwest Nelson, New ZealandOlivia M Hyatt, James Shulmeister, Chris C. SmartOlivia M Hyatt (corresponding author), Department of Geological Sciences, University of Canterbury, New ZealandFax: +64 3 364 2769 Email: omh13@student.canterbury.ac.nzJames Shulmeister, Department of Geological Sciences, University of Canterbury, New ZealandEmail: james.shulmeister@canterbury.ac.nzChris, C. Smart, Department of Geography, Social Science Centre, University of Western Ontario, CanadaEmail: csmart@uwo.caAbstractA preliminary investigation of past glacial activity onthe Owen Massif in northwest Nelson, New Zealandis presented. There is good evidence for extensive iceaccumulation on the massif. Glacial erosional featuressuch as U shaped valleys, ice smoothed bedrock knobsand glaciokarst pavements are widespread. Preservationof glacial depositional landforms is poor, because of theextensive karst processes operating on the massif andfluvial action in the valleys. Sediment accumulation wasconcentrated in large pre-existing karst depressionscentered on and around Sentinel Hill. The glacial landformsand processes appear different from surroundingnorthwest Nelson landscapes. No true terminal positionshave been identified, though it is clear that icedid flow off the massif and advanced at least a few kilometresdown the upper Granity and Owen valleys.Fluvial valley forms dominate the valleys radiatingfrom the massif where initial U shapes valleys quicklybecome fluvial incised. Further investigation is warrantedin the caves, where sediments and speleothemspotentially hold the best archives of glaciation.IntroductionMount Owen is the highest peak of a spectacular upthrustedmarble massif at the southern end of KahurangiNational Park, northwest Nelson, New Zealand(Figure 1). The Owen Massif has been stated to be thebest example of glacial karst in New Zealand (Williams,1992), but there has been no specific study on theglacial landforms or sediments on the massif. Thispaper presents the results of a reconnaissance glacialstudy of the Owen Massif.Glaciation was widespread in the mountains of SouthIsland during the Quaternary (e.g. Suggate, 1965) butthe main ice cover was confined to the Southern Alpsand splay ranges. To the east and south of Mt Owen, icesourced from the Nelson Lakes area (Figure 1) extendedinto the Buller River. These ice advances have receivedmuch attention from Suggate (1965, 1988 & 1993) whohas mapped out a series of moraine limits (near theNelson Lakes) and inferred correlations along the BullerRiver using terrace slopes and levels.Evidence for glaciation in northwest Nelson was firstmentioned by Dobson (1872), with more a substantialsurvey by Henderson (1923 & 1931). Most of this workconcentrated on the Arthur Range and Tasman mountains(Figure 1) to the north. More recently, Shulmeisteret al. (2001; 2005) published in depth studies of theglacial history and chronology of the Cobb Valley, inthe Tasman Mountains. Work by groups from Canterburyand Victoria Universities is ongoing in the Tasmanmountains and adjacent areas. Published work on theOwen Massif is sparse. Henderson (1931) inferredglaciers of about three kilometres in length drainingthe northern Owen massif into Nuggety and Blue creeksand ice draining from the southern half of the massifinto the gorges of the Fyfe and Owen rivers. No terminalpositions were identified.Coleman (1981) briefly mentioned moraines on MtOwen and terraces relating to the last glaciation inthe Wangapeka and Owen valleys. The aggradationalterraces were loosely related to two aggradationalFigure 1 (left). Location of northwest Nelson and Owen Massif,with major rivers, lakes and mountain ranges in the area.11 | Quaternary AUSTRALASIA 24 (2)