QA_Vol 24_No 1_July 2007 - Australasian Quaternary Association

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A Reconnaissance Study of Glaciation on the Owen Massif CONTINUEDFigure 2 (left).Geology of the Owen Massif(modified from Coleman, 1981)and location of the majorgorges adjacent to the massif.Figure 3 (right).Simplified geomorphologicalmap centered on Sanctuary Basin,with insert of the main OwenMassif landmarks.sequences of Speargrass and Tophouse formationsdefined by Suggate in the Nelson Lakes area. Correlationinto the upper Owen valley was tentative asColeman could not link the moraines on the massif tothe terraces in the Buller. Williams (1992) in an overviewof New Zealand karst, mentions some glacial and karstlandforms on the massif. A map of ice extent andlocation was included. He described small scaleglaciation on the massif and a central ice-field in theSentinel Hill area, which had small glaciers radiatingto the north, west and east of this central accumulationzone. He also states that ‘the topography of the regionappears essentially freshly glacial’. In summary, theexistence of glacial features on the massif is widelyaccepted but absence of any coherent marginal featureshas prevented any fuller description and interpretation.Physiography & GeologyThe Owen Massif is a raised block of marble, c. 35square km in area, roughly 4 km wide and 9 km longaligned about a northeast–southwest axis. Most of themassif is above 1300 m and it has a number of peaksabove 1700 m with three over 1800 m (Figure 3). Theedges of the massif are very steep, locally vertical, andthere is a 300–500 m drop to the valley floors that ringthe massif. NW Nelson contains many of the oldestrocks in New Zealand and is part of the Australianplate. As such it contains extensive areas of granites,metamorphosed limestones (marbles) and volcanicmeta-sediments of Palaeozoic and Mesozoic ages(Rattenbury et al., 1998). Major faults dissect thelandscape into a number of fault bounded structuralslices. The Mt Owen massif is up-thrusted between theOwen and Dart faults (Coleman, 1981), both runningnorth to northeast. The massif is composed of TakakaTerrane (Figure 2) rocks including the Owen, ArthurMarble and clastic Wangapeka Formations (Rattenburyet al., 1998).The Owen Formation, a largely siliceous unit andoutcrops on the south side of the massif (Figure 2),conformably underlies the Arthur Marble Formation(Coleman, 1981 & Rattenbury et al., 1998). The ArthurMarble Formation is primarily a light grey coarsegrainedmarble, with some dark siliceous sandy bedsand chert nodules. It is intensely deformed, and has athickness of about 1500 metres (Coleman, 1981). Itcomposes most of the Owen massif (Figure 2). TheWangapeka Formation conformably overlies ArthurMarble and outcrops locally over parts of the massif(Figure 2). On the massif it is composed of laminatedsiliceous dark grey pyritic siltstone and lighter sandstonebeds with black carbonaceous horizons and thinquartzite beds (Coleman, 1981). These clastic sedimentsare important as they preserve a record of glaciationmore strongly than the carbonates.The eastern side of the massif is bounded by the DartFault (Figure 2). To the east of the fault highly weatheredSeparation Point Granite outcrops as the roundedLookout Range. The contact roughly runs along the12 | Quaternary AUSTRALASIA 24 (2)
upper valley floors of the Owen and Granity valleys(Muir et al, 1995). In addition to the Separation PointGranite in the Lookout Range, two small inliers ofhornblende rich Andesite of slightly older age (RiwakaIgneous Complex) crop out on the western side of themassif itself (Figure 2).There is extensive glacial karst including some of thelongest, deepest and oldest caves in New Zealand. Thesurface is a classical “rundhocker” karst composed ofglacially sculpted roche mountonees variously solutionallyetched by a range of karren, particularly in bedsof purer marble. Between ridges is a wide spectrum ofdolines some over 500m in diameter. Some dolines aremerely sinks for local karren fields, others are abandonedkarst shafts truncated by glacial erosion, whileothers are choked by debris and many doline fields aredeveloping in recent alluvial deposits that floor largerdoline forms. Some dolines are aligned and may reflectgeological lineaments and contacts promoting caves.ClimateThere are few formal climate records for this area. Thetwo closest stations are at Wangapeka (elevation 259m,decommissioned), about 16km northeast of Mt Owenand Murchison township (elevation 158m), south westof the massif (Figure 1). From 1941 to 1970 the stationat Wangapeka recieved an average of 1771 mm per year,and Murchison had 1558 mm per year (NZMS, 1970).There is a strong orographic and west-east precipitationgradient in northwest Nelson. The Owen massif interruptsthis westerly flow and will have a much higherprecipitation total due to its higher elevation. For twosummers (1967/68 and 1968/69) minimum and maximumtemperatures were measured intermittently byBell (1970) at Granity Pass Hut. Daily temperaturesranged from about -1°C to 26°C. Even more limiteddaily readings in winter ranged from about -5 to 10°C.MethodsField work was undertaken over the summers of 2004and 2005, based largely from Granity Pass Hutt (Figure3). Areas of the north and southwest of the massif werecovered during a number of multi day trips. Glacial andkarst geomorphic features where mapped at a scale of1:30 000 on aerial photographs and the Wangapekatopographic map sheet (M28). Because of limited fieldtime and the nature of the area not all parts of themassif were fully field checked. The majority of theglacial deposits and other substantial glacial evidence isconcentrated in the northern part of the massif, whichis presented here as figure 3. A glacial geomorphologicalmap of the whole massif is presented as anappendix online (www.aqua.org.au).In the field, hand specimens of rocks from inferredmoraines were examined for glacial phenomena (striations,faceting etc), though outcrops were poor andsparse. Some samples from boulders on the northernflank of Sentinel Hill were recovered for cosmogenicexposure dating, though the results from this are notyet to hand.13 | Quaternary AUSTRALASIA 24 (2)
Page 1 and 2: Volume 24 | Number 2 | July 2007Qua
Page 3 and 4: EditorialPresident’s PenDear Fell
Page 5 and 6: Interview withProfessor Liu Tungshe
Page 7 and 8: about Dr Ding [Ting]. He was the fi
Page 9 and 10: Figure 3: The first Australianvisit
Page 11 and 12: Figure 4: Dinner in Luikiang,1975.
Page 13: Research ArticleA Reconnaissance St
Page 17 and 18: Figure 4. (above) Photo ofSanctuary
Page 19 and 20: volume of ice would have accumulate
Page 21 and 22: Research ArticleLate Pleistocene en
Page 23 and 24: Table 1: Revised 14 C Ages for Sect
Page 25 and 26: ResultsMicrofossilsThe quantitative
Page 27 and 28: Figure 4. Ostracod, mollusc and sta
Page 29 and 30: high-energy events such as floods p
Page 31 and 32: Research ArticleCarbon isotope disc
Page 33 and 34: isotope tissue values. Differences
Page 36 and 37: Meeting ReportReport on the Symposi
Page 38 and 39: Report on the Symposium ‘Land-Oce
Page 40 and 41: Australia and NZ Geomorphology Grou
Page 42 and 43: Conference ReportThe 2nd Internatio
Page 44 and 45: Global Change and Earth System Scie
Page 46 and 47: Book ReviewsEvolution and Biogeogra
Page 48 and 49: Thesis AbstractsA Late Quaternary p
Page 50 and 51: Thesis Abstracts CONTINUEDthat, alt
Page 52: Quaternary AUSTRALASIAQuaternary Au

QA_Vol 24_No 1_July 2007 - Australasian Quaternary Association

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