Geology of the Kaikoura Area - GNS Science

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Figure 57 St Oswalds Churchon State Highway 1 at Wharanuiis built from blocks of Mead HillFormation, quarried locally fromWoodside Creek.Rip-rap is readily obtainable. Potential sources includeigneous rocks northwest of the Alpine Fault, andsandstone-dominated parts of the Torlesse compositeterrane and Paleogene limestones southeast of the fault.Rip-rap is used for river bank or coastal protection and islargely obtained from hard rock quarries. Talus deposits,such as ultramafic-derived boulders on the southwest ofthe Red Hills, have been used locally because of theirproximity to the area of demand.Argillite blocks within the serpentinitic Patuki Mélangeof east Nelson have been altered by the introduction ofminerals such as albite and tremolite. River boulders ofaltered argillite (pakohe) are tough with a characteristicconchoidal fracture. They were worked by Maori into adzesand other implements.Dimension and ornamental stone of varying rock type arereadily available, but the quantities obtained to date havebeen small. Basement rocks are commonly jointed andfractured, and generally difficult to access. A blackgabbronorite in the Rotoroa Complex in the Howard valleynear Lake Rotoroa has been investigated as a source ofdimension stone. Although it is readily accessible, closelyspaced jointing would limit the size of blocks to
Dunite boulders are sporadically collected from streamsdraining from the Red Hills into the Wairau River for use insaunas and hangi because they withstand rapid coolingwithout explosively disintegrating.CoalCoal occurs locally in rocks of Late Cretaceous age andcommonly near the base of Paleogene sequences. However,the only coal of economic significance in the map area is inthe Murchison Basin (Suggate 1984). Up to five seamshave been recorded from the basal Maruia Formation nearthe lower Matiri valley. Although the coal is stronglyswelling and of high-volatile bituminous rank, the seamshave a maximum thickness of only 1.2 m, the structure isunfavourable for mining and the coal has a medium to highsulphur content. The Longford Formation in the lowerMatakitaki and Owen valleys contains several seams oflow-swelling, low-moisture, high-volatile bituminous coalwith low (c. 1%) sulphur. The seams pinch and swell,reaching a maximum thickness of 3 m, and the coal iscommonly crushed. The easily accessible coal has beenworked out and, because of the irregularity of the seamsand structure, the prospects for renewed mining are poor.Total production was probably in the order of 150 000tonnes (Suggate 1984).WaterGroundwater availability is generally restricted east of theMain Divide where rainfall is lower and aquifers have limitedextent. The best yields occur in Late Quaternary alluvialgravel, particularly adjacent to the major rivers drainingthe hard basement rocks or from the fan gravel aprons onthe flanks of the major ranges (Brown in Eggers & Sewell1990). In the lower Awatere valley, the gravels are thin andoverlie Pliocene siltstone of low permeability that restrictsriver recharge. In the minor rivers and streams, includingthose draining soft and/or weathered rock, an increase infine-grained material in the gravel deposits tends to reducepermeability. Along the coast, Holocene beach sands anddunes have a high permeability and porosity but rechargein many areas is dependent on frequent rainfall, and overextractioncan result in saline intrusion (Doole & others1987; Brown in Eggers & Sewell 1990). The Neogene toPleistocene gravel and sand deposits have generally low,but usually reliable yields.The pre-Quaternary Cenozoic rocks in the mapped areagenerally have few open joints, and except along faultplanes and in limestones, groundwater yields are low. Thebasement rocks have numerous joints, particularly alongfault zones, which provide sufficient permeability to yieldsmall quantities of groundwater. In some basement rocks,such as schist, igneous and early Paleozoic rocks, thepresence of sulphide minerals tends to reduce water quality.However, where this occurs surface water supplies areabundant.Thermal and mineralised hot springs are widespread,although not common, throughout the Southern Alps andthe ranges of northern Canterbury (Mongillo & Clelland1984). These springs are the result of groundwaterpercolating to considerable depth along fault zones beforedischarging on valley floors (Barnes & others 1978; Allis& others 1979). Measured temperatures range from 27.5°Cto 60°C and are commonly accompanied by a sulphurousdischarge (Mongillo & Clelland 1984). Commercial thermalresorts have been developed at Hanmer Springs and MaruiaSprings along the Hope and Fowlers faults respectively.Oil and gasOil and gas shows are present in a number of places withinthe Murchison Basin. The basin contains approximately9000 m of Late Eocene to Miocene sedimentary rocks in itscentre and up to a further 3000 m may have been removedby erosion (Nathan & others 1986). The basin was drilledin the late 1920s and in 1968, 1970 and 1985 although onlythe last hole, Matiri-1, reached bedrock (at 1467 m; Dunn& others 1986). The rocks in the basin are generally steeplydipping, having been folded into a series of synclinesseparated by faulted anticlines. No closed structural trapsare known and there are few potential reservoir rocks withsufficient permeability or porosity, and consequently thehydrocarbon prospects are assessed as low (Nathan &others 1986).In Marlborough, oil seeps are known from Pahau terranerocks at London Hill and the Amuri Limestone in IsolationCreek, south of the Waima River. Both seeps occur in closeproximity to major faults. The oil is likely to have beensourced from the Late Cretaceous Seymour Group and havemigrated up the fault zones to the surface (Field, Uruski &others 1997). While both source rocks and potentialreservoir rocks are favourable, deformation has limited thepossibility of any significant hydrocarbon traps. Mudstoneat the base of the Amuri Limestone in Mead Stream hasbeen correlated with the Waipawa Formation, ahydrocarbon source rock in the eastern North Island (Field,Uruski & others 1997). However, in Marlborough, themudstone is only a few metres thick, and significanthydrocarbon potential from this rock is unlikely.In northern Canterbury hydrocarbons have been reportedfrom a number of locations, principally in the Cheviot area(Field, Browne & others 1989). Several seeps occur in theTorlesse rocks although the hydrocarbons are most likelyto have originated in adjacent Late Cretaceous-Paleogenerocks (e.g., the Eyre Group), which include potential sourceand reservoir rocks as well as other seeps. Significantstructural traps have not yet been identified, and there isthe potential for stratigraphic traps. Gas containing a veryhigh ethane content escapes from the Hanmer thermalsprings (Field, Browne and others 1989).The offshore area of the Kaikoura map has had limitedpetroleum exploration but seismic data of varying qualityhas identified several deep sedimentary basins (Uruski1992; Field, Uruski & others 1997). The basins may containpotential source rocks that have been buried sufficientlyto generate hydrocarbons.53
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1 : 2 5 0 0 0 0 G e o l o g i c a l
Page 7:
ABSTRACTThe Kaikoura 1:250 000 geol
Page 10 and 11: 27 10722181725814362333322621243128
Page 12 and 13: ProvinceSEDIMENTARY AND VOLCANIC RO
Page 14 and 15: Main Divide rangesGEOMORPHOLOGYThe
Page 16 and 17: Figure 9 Basin and range topography
Page 18 and 19: Figure 12 The active Alpine (Wairau
Page 20 and 21: 290PermianCarboniferous354Late Devo
Page 22 and 23: iotite granite, locally with megacr
Page 24: interlayered with the Rotoroa Compl
Page 28 and 29: Figure 19 Maitai Group sedimentary
Page 30 and 31: Torlesse composite terraneThe Torle
Page 32 and 33: Permian to Late Triassic semischist
Page 34: Zones of intra-Pahau mélange, char
Page 37 and 38: CRETACEOUS TO PLIOCENEFollowing ama
Page 39 and 40: Figure 31 Interbedded sandstone and
Page 41 and 42: Figure 34 The Seymour Group include
Page 43 and 44: of feldspar-clinopyroxene-biotite-a
Page 45 and 46: The Amuri Limestone (Pza, Eza) is w
Page 47 and 48: overlies older rocks (Carter & Land
Page 49 and 50: Late Miocene to earliest Late Plioc
Page 51 and 52: QUATERNARYThe tectonic regime initi
Page 53 and 54: Figure 52 Screes on the southern fl
Page 55 and 56: Marine depositsMarine sand and grav
Page 57 and 58: and/or non-deposition (including th
Page 59: hydrous mica clay are widespread as
Page 63 and 64: GEOLOGICAL HAZARDSParts of the Kaik
Page 65 and 66: The Modified Mercalli Intensity sca
Page 67 and 68: Table 2. Mean return periods for ea
Page 69 and 70: REFERENCESAdams, C.J. 2003: K-Ar ge
Page 71 and 72: Childerhouse, S.J.; Dawson, S.M.; S
Page 73 and 74: Holdaway, R.N.; Worthy, T.H. 1997:
Page 75 and 76: McPherson, R.I. 1988: Experimental
Page 77 and 78: Stewart, R.B. 1974: Geology of Mt M
Page 79: This map and text illustrate the ge
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Geology of the Kaikoura Area - GNS Science

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