Geology and mineral resources of the Northern Territory

Ahmad M and Munson TJ (compilers)

Northern Territory Geological Survey Special Publication 5

Chapter 30: Kalkarindji Province

BIBLIOGRAPHIC REFERENCE: Glass LM, Ahmad M and Dunster JN, 2013. Chapter 30: Kalkarindji Province: in Ahmad M and Munson TJ (compilers). ‘Geology and mineral resources of the Northern Territory’. Northern Territory Geological Survey, Special Publication 5.

Disclaimer While all care has been taken to ensure that information contained in this publication is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of its information. The Northern Territory of Australia gives no warranty or assurance, and makes no representation as to the accuracy of any information or advice contained in this publication, or that it is suitable for your intended use. You should not rely upon information in this publication for the purpose of making any serious business or investment decisions without obtaining independent and/or professional advice in relation to your particular situation. The Northern Territory of Australia disclaims any liability or responsibility or duty of care towards any person for loss or damage caused by any use of, or reliance on the information contained in this publication. Kalkarindji Province Current as of October 2010

Chapter 30: KALKARINDJI PROVINCE LM Glass, M Ahmad and JN Dunster

INTRODUCTION (Glass et al 2006, Glass and Phillips 2006). Figure 30.1 shows the outcrop distribution and probable original extent During the early Cambrian, a widespread outpouring of of the province in Australia. Since it extends across a vast sub-aerial basaltic lava covered a large area of northern area in excess of 106 km2 (Glass and Phillips 2006) and was Australia, central Western Australia, northwestern South probably emplaced over a very short geological time interval, Australia and possibly areas of South East Asia that have LWLVFODVVL¿HGDVD/DUJH,JQHRXV3URYLQFH /,3 sensu&RI¿Q subsequently been rifted from Australia. Stratigraphically and Eldholm (1992). The name Kalkarindji Volcanic Group equivalent exposures of this volcanic succession have was erected by Kruse in Rawlings et al (2008) to include historically been given different names; these include the some components of the Kalkarindji Province in the NT and Antrim Plateau Volcanics, Nutwood Downs Volcanics, parts of WA, including minor intercalated sedimentary units. Helen Springs Volcanics and Peaker Piker Volcanics in the +RZHYHUWRLQFOXGHDQGEHWWHUGH¿QHDOOFRQVWLWXHQWLJQHRXV Northern Territory, and the Colless Volcanics (Bultitude units, this name is herein formally replaced by Kalkarindji 1976) in Queensland. Coeval basaltic and intrusive rocks Suite (see below). LQWKH2I¿FHU%DVLQLQFHQWUDO:HVWHUQ$XVWUDOLDDQG NTGS airborne magnetic data (Clifton 2008) indicate South Australia include the Table Hill Volcanics (Peers WKDWEDVDOWLFODYDÀRZVLQWKH17DUHH[WHQVLYHO\FRQWLJXRXV 1969, Jackson and van de Graaff, Veevers 2000, Glass under covering strata across the Ord, Bonaparte, Daly, and Phillips 2006) and informally named Boondawari northern Wiso and northern Georgina basins. Figure 30.2a dolerite (MacDonald et al 2005). The Milliwindi Dolerite shows the extent of outcropping Kalkarindji Province rocks (Hanley and Wingate 2000) and the informally named overlain on the First Vertical Derivative aeromagnetic image Mount Ramsay dolerite of the Kimberley region of WA for an area within the Palaeo–Mesoproterozoic Birrindudu (Glass 2002) are also included as a part of this igneous event. and Meso-?late Neoproterozoic Victoria basins of the Based on geochemical and isotopic similarities, Glass (2002) 1 The name Kalkarindji is derived from the place name in WAVE LQFOXGHGDOORIWKHVHFRHYDOPD¿FLJQHRXVXQLWVZLWKLQDQHZ +,//2 (Gazetteer of Australia 2004). province, and named it the Kalkarinji Continental Flood 2 Names of 1:250 000 mapsheets are shown in large capital letters Basalt Province, but later revised the spelling to Kalkarindji1 HJ:$9(+,//

111° 114° 117° 120° 123° 126° 129° 132° 135° 138° 141° 144° 147° 150° 153°

-10° Money Shoal-1 Kalkarindji Suite (outcrop extent) ? -12° Diamond drillhole ? Antrim Plateau Darwin Probable minimum Rifted Volcanics ? original extent of -14° margin Cambrian large igneous event Milliwindi (former) Nutwood Dolerite Downs Volcanics -16°

-18° ?

-20° Colless Volcanics Boondawari dolerite (under cover) -22° Helen Springs Volcanics ? (former) Peaker Piker Volcanics Table Hill ? ? -24° Volcanics Alice Springs

-26°

-28°

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0 250 500 km

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A09-202.ai -36° Figure 30.10DSRI$XVWUDOLDVKRZLQJRXWFURSH[WHQWRI.DONDULQGMLPD¿FURFNV JUHHQDUHDV 'DVKHGOLQHVKRZVSRVVLEOHPLQLPXP RULJLQDOH[WHQWRI.DONDULQGML/DUJH,JQHRXV3URYLQFH PRGL¿HGDIWHU*ODVVDQG3KLOOLSV %RRQGDZDULGROHULWHGRHVQRWKDYHVXUIDFH H[SRVXUH6RXWKHUQPDUJLQQRUWKRI$OLFH6SULQJVLVWHQWDWLYHO\ORFDWHGWRLQFOXGHFRHYDOJHRFKHPLFDOO\VLPLODUPD¿FURFNVLQHDVWHUQ $UXQWD5HJLRQ /DZOH\:KHODQet al 2010).

Geology and mineral resources of the Northern Territory 30:1 Special publication 5 Kalkarindji Province

a 129º30' 130º00' 130º30'131º00' 131º30' 132º00'

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A09-205.ai 0 25 50 km Kalkarindji flood basalt (outcrop extent) Location of Figure 30.2b Northern Territory. The magnetic imagery Figure 30.2b b 129º30' UHYHDOVWKDWRXWFURSSLQJDQGQHDUVXUIDFHEDVDOWÀRZVDUH GH¿QHGE\GLVWLQFWLYHµULSSOHG¶WH[WXUHVWKDWFDQEHHDVLO\ traced under shallow cover. Kruse in Rawlings et al (2008) synonymised the Nutwood Downs Volcanics in HODGSON DOWNS Neave Fault with the more extensive Antrim Plateau Volcanics. Subsurface contiguous volcanic and minor sedimentary rocks to the east of the Tennant Region are extensive beneath the central Georgina Basin. The names Helen Springs Volcanics and Peaker Piker Volcanics have been historically applied to these strata, but these names were synonymised by Kruse in Rawlings et al (2008) as Helen 18º30' Springs Volcanics. Historically, Hardman (1885) and Jensen (1915) provided the earliest descriptions of the Antrim Plateau Volcanics in the East Kimberley and Victoria River regions of northern Australia. Hardman (1885) named hilly dissected country, to the east of the Elvire River in the eastern Kimberley district, as the Great Antrim Plateau. Thirty years later, Jensen (1915) documented and described volcanic rocks in the Victoria River, Edith River and Daly River regions, and suggested they were most likely to be of Carboniferous or Permo-Carboniferous age. David

0 25 km A09-251.ai  ¿UVWQDPHGWKHµ$QWULP3ODWHDX%DVDOWV¶EDVHGODUJHO\ on the description of the Great Antrim Plateau of Hardman Figure 30.2. (a) Kalkarindji Suite outcrop extent (green areas) (1885). However, this name was changed by Traves (1955) to overlain on First Vertical Derivative aeromagnetic image (Clifton µ$QWULP3ODWHDX9ROFDQLFV¶WRUHÀHFWWKHKHWHURJHQHLW\RIWKH 2008) for a selected area within Birrindudu and Victoria basins, units. Edwards and Clarke (1941) undertook a petrographic 1RUWKHUQ 7HUULWRU\ VHH LQVHW IRU ORFDWLRQ %DVDOWLF ÀRZV XQGHU FRYHUGLVSOD\DGLVWLQFWLYHµULSSOHG¶SDWWHUQ b) Red boxed area study of basalts in the eastern Kimberley region, where they RI D VKRZLQJH[WHQWRIEDVDOWLFÀRZVXQGHUFRYHU JROGOLQHV  described the rocks as ranging from olivine basalt to quartz Green areas indicate Kalkarindji outcrop extent. basalt. They suggested that the eastern Kimberley basalts

Geology and mineral resources of the Northern Territory 30:2 Special publication 5 Kalkarindji Province formed a single basaltic province. Traves (1955) described the altered angular to rounded fragments of vesicular and basalts in the Ord–Victoria River region and suggested that amygdaloidal basalt set in an aphanitic, heavily altered isolated suites of Cambrian basalts across northern Australia basaltic matrix), minor basaltic lavas and thin lenses of perhaps belonged to a single period of volcanic activity. A sandstone and siltstone in the southern Victoria River GHFDGHODWHU5DQGDODQG%URZQ  H[DPLQHGWKH¿HOG region as the Blackfella Rockhole Member. The volcanic relationships, petrography and chemistry of the Antrim detritus in agglomerate bands is thought to have been Plateau Volcanics as a part of their study of the northern Wiso derived from highly explosive volcanic activity and the Basin. Dunn and Brown (1969) suggested a correlation of presence of thin lenses of sandstone and siltstone within stratigraphically equivalent early Cambrian volcanic rocks agglomerate bands is indicative of pyroclastic deposition in other parts of the Northern Territory and Queensland with under sub-aqueous conditions. Sweet et al (1974b) also the more extensive Antrim Plateau Volcanics. Bultitude (1971, described and formally named glomeroporphyritic (in 1976) subsequently provided a more detailed description of this case, grouping of plagioclase phenocrysts into the stratigraphic succession, chemistry and mineralogy of distinct clusters) and often columnar jointed basalts these volcanic rocks and reinforced the possible correlation of in the same region as the Bingy Bingy Basalt Member. FRHYDOPD¿FXQLWVDFURVVPXFKRIQRUWKHUQ$XVWUDOLD0RU\ The Blackfella Rockhole and Bingy Bingy Basalt and Beere (1988) also provided a detailed description of basalts 0HPEHUVDUHDOVRUHFRJQLVHGLQ',;215$1*(DQG in the Bonaparte and Ord basins and indicated a maximum /,66$'(//LQ:$DQGWKHVHPDSVKHHWVDOVRLQFOXGH WKLFNQHVVIRUWKHEDVDOWLFODYDÀRZVRIDERXWP0RUH the intercalated Mount Close Chert Member. There are recently, Glass (2002) undertook a comprehensive study of the at least ten other intercalated sedimentary units mapped mineralogy, geochemistry, geochronology and petrogenesis of in the NT. Correlation of sedimentary and volcanic units the entire province. is hampered by poor outcrop and their generally limited The volcanic rocks consist predominantly of basaltic areal extent, but a suggested correlation for the Victoria ODYD ÀRZV PLQRU ÀRZ EUHFFLD DQG DJJORPHUDWH DQG River region is shown in Figure 30.3. The units include intrusive dolerite dykes that are found in Western Australia. widespread carbonate, agglomerate and pyroclastic Thin interbeds (generally <10 m thick) of well sorted cross- DFFXPXODWHVRIWHQDVVRFLDWHGZLWKEDVDOWÀRZWRSVDQG bedded sandstone, siltstone, chert, sedimentary breccia and bottoms, and sandstone beds, which are generally of VLOLFL¿HGVWURPDWROLWHV Conophyton sp) are locally present more limited areal extent and typically less than 10 m (Sweet et al (1974b). thick. The sandstones are typically cross-bedded and are variously tuffaceous, quartzic, feldspathic or ferruginous. EARLY CAMBRIAN Many of the carbonate units were originally stromatolitic, EXW DUH QRZ VLOLFL¿HG DW WKH VXUIDFH Figure 30.3 Kalkarindji Suite indicates that the Bingy Bingy Basalt Member extends IURP/,0%81<$LQWR9,&725,$5,9(5'2:16 /DWHHDUO\&DPEULDQYROFDQLFXQLWVRIWKH.DONDULQGML ,QWKH17DQHTXLYDOHQWXQLWWRWKH0RXQW&ORVH&KHUW ÀRRGEDVDOWSURYLQFHLQQRUWKHUQ$XVWUDOLDZHUHSUHYLRXVO\ Member in WA indicates that carbonate deposition formalised as the Kalkarindji Volcanic Group (Kruse H[WHQGHG IURP :$ DW OHDVW DV IDU HDVW DV 9,&725,$ in Rawlings et al WKLVGH¿QLWLRQDOVRLQFOXGHG 5,9(5 '2:16 'ULOOKROH $17' *ROH DQG /HH various minor intercalated and immediately underlying  LQ%,55,1'8'8FRUHGDPWKLFNVWURPDWROLWLF sedimentary units. However, given the dominance of the limestone and matrix-supported basalt breccia that might LJQHRXV FRPSRQHQW WKH IRUPDO VWUDWLJUDSKLF GH¿QLWLRQ be the original rock now represented by the Mount Close IRUWKLVSURYLQFHLVKHUHUHGH¿QHGDVWKH.DONDULQGML6XLWH Chert Member at the surface. However, it has been (see Appendix), so as to include volcanic and intrusive suggested by Walter (1972) that conical stromatolites constituents (see Geoscience Australia Stratigraphic from the constituent Mount Close Member (Mory and Units Database website). Minor intercalated sedimentary Beere 1988) of the Antrim Plateau Volcanics in WA, may components of the former Kalkarindji Volcanic Group are represent a hot springs environment, in which conical QRWLQFOXGHGZLWKLQWKHIRUPDOGH¿QLWLRQRIWKH.DONDULQGML stromatolites are known to develop even up to the present Suite, but are included within the constituent formations. (Walter et al 1976). They therefore do not provide an age The Antrim Plateau Volcanics (Traves 1955) constraint. Nevertheless, recent isotopic dating results unconformably overlie Proterozoic basement rocks and (see Geochronology FRQ¿UPDODWHHDUO\&DPEULDQ underlie sedimentary rocks of the Ord, Daly, northern age for the volcanic rocks. Also intercalated within the Wiso and northern Georgina basins in the NT, and the Antrim Plateau Volcanic succession is the Malley Spring Ord, Bonaparte and eastern Kimberley basins in Western Member (Mory and Beere 1985). This is a 3–5 m-thick Australia. The unit may extend further to the north siltstone and sandstone unit that occurs about 50 m above in the Arafura Basin, as red-brown volcanic rocks in the base of the Antrim Plateau Volcanics over a distance drillhole Money Shoal-1 (Figure 30.1) have historically of 25 km in the Ord Basin in WA. been correlated with the Antrim Plateau Volcanics Units that were previously included in the Kalkarindji (Petroconsultants Australasia 1989). Moreover, regional Volcanic Group of Kruse (in Rawlings et al 2008) include the thermal subsidence in the Arafura Basin has been attributed 'Jarong Conglomerate' (Pontifex and Mendum 1972, Sweet to Antrim Plateau volcanism (Struckmeyer 2006). et al 1974a), which is now subsumed as the Uniya Formation Sweet et al (1974b) described and formally named (see Wolfe Basin), the Kinevans Sandstone (Sweet et al intercalating agglomerate (consisting of extensively 1974b; see Wolfe Basin) and the Jindare Formation

Geology and mineral resources of the Northern Territory 30:3 Special publication 5 Kalkarindji Province

(Needham and Stuart-Smith 1984, Kruse et al 1994). The Victoria River region resulted in nine stratigraphic drillholes IRUPHU -DURQJ&RQJORPHUDWH  )(5*866215,9(5'$/< (Bultitude 1971, Figure 30.6) and a maximum thickness 5,9(5 GLUHFWO\XQGHUOLHVWKH$QWULP3ODWHDX9ROFDQLFV RIPRIEDVDOWLFVXFFHVVLRQZDVGULOOHGLQ/LPEXQ\D DQG WKH .LQHYDQV 6DQGVWRQH :$7(5/22  LV WKRXJKW WR (Figure 30.7). However, this is a minimum thickness for conformably underlie the Antrim Plateau Volcanics in the basalt in this region, as the drillhole was terminated while Victoria River Region (Kruse in Rawlings et al 2008). The VWLOOLQWKHYROFDQLFVXFFHVVLRQ,QWKH.DONDULQGML±7RS -LQGDUH )RUPDWLRQ 3,1( &5((. )(5*86621 5,9(5 Springs area, the Antrim Plateau Volcanics attain a thickness .$7+(5,1( LVD!PWKLFNXQIRVVLOLIHURXVXQLWRI of about 250 m and in the Tanami Region, it is less than 30 m quartzofeldspathic sandstone, often with characteristic low- in thickness (Blake et al  0RUHUHFHQWO\*ROHDQG/HH DQJOH FURVVEHGV PXGVWRQH VLOLFL¿HG FDUERQDWH URFNV DQG (2005) described intersections of almost 500 m of basaltic localised conglomerate, that laterally interdigitates with the ÀRZVXFFHVVLRQVLQGULOOKROH$17'RQ/,0%81<$ Antrim Plateau Volcanics along the northeastern margin ZKHUHWKHWKLFNHVWLQGLYLGXDOÀRZHQFRXQWHUHGZDVDOPRVW RIWKH'DO\%DVLQ,WZDVSUREDEO\GHSRVLWHGLQDOLWWRUDO  P WKLFN 7KH ÀRZ DW WKH EDVH RI WKH VXFFHVVLRQ DQG shoreface, ?marine environment (Kruse et al 1994, Kruse in overlying basalt breccia, is correlated with units in drillhole Rawlings et al 2008). ANTD001, about 20 km away. The Antrim Plateau volcanic succession has its greatest The Antrim Plateau Volcanics unconformably thickness in the eastern Kimberley region, where successive overlie Proterozoic basement of various ages in the EDVDOWÀRZVGLSƒWRWKHHDVWDQGDWWDLQDPD[LPXPWRWDO eastern Kimberley region of Western Australia. This WKLFNQHVVRIDERXWP,QGLYLGXDOQRQYHVLFXODUEDVDOWLF includes the Neoproterozoic Albert Edward Group ÀRZVLQWKLVVXFFHVVLRQDUHVHSDUDWHGE\FRQVSLFXRXVYHVLFXODU (Dow and Gemuts 1967), where the contact is a narrow ÀRZXQLWV7ZRVWUDWLJUDSKLFVHFWLRQVRIDSSUR[LPDWHO\ thermal aureole in sandstone. The volcanics probably 800 m and 600 m thickness were measured by Glass (2002) unconformably overlie the Moonlight Valley Tillite of DW3XUQXOXOX1DWLRQDO3DUNLQ',;215$1*(DQGDW the Wolfe Basin in AUVERGNE (Dunster et al 2000). trigonometric station J32 of Hardman (1885) in GORDON ,QWKH9LFWRULD5LYHUUHJLRQRIWKH1RUWKHUQ7HUULWRU\ DOWNS in the Kimberley region, respectively (Figure 30.4). EDVDOWLFODYDÀRZVRIWKH$QWULP3ODWHDX9ROFDQLFV Minor interbedded siltstone units are present at about 100 m unconformably overlie the Proterozoic Wattie, Bullita from the base of the succession at Purnululu National Park. and Tijunna groups (Birrindudu Basin) and Auvergne ,QWKH1RUWKHUQ7HUULWRU\WKHJUHDWHVWRXWFURSH[WHQWLVLQ Group (Victoria Basin; Beier et al ,Q+2'*621 WKH 9LFWRULD 5LYHU UHJLRQ ZKHUH VXFFHVVLYH EDVDOWLF ÀRZV DOWNS, the Antrim Plateau Volcanics (former Nutwood form prominent mesas capped by resistant agglomerate and Downs Volcanics) unconformably overlie the Bukalara YHVLFXODUÀRZWRSVRIWKH%ODFNIHOOD5RFNKROH0HPEHUVRXWK 6DQGVWRQH 'XQQ ,QLWLDOO\D&DPEULDQDJHZDV RIWKH:HVW%DLQHV)DXOWLQ:$7(5/22 Figure 30.5). The suggested for the Bukalara Sandstone due to the presence mesas are remnants of a much greater land surface dissected of tube-like structures thought to be the trace fossil by modern-day stream systems. A BMR drilling project in the Skolithos sp (Muir 1980). Dunnet (1965) and Plumb and

Fergusson Lissadell Dixon Range Wave HillWaterloo V.R.D. Limbunya River Delamere Auvergne WA WA

_ _ _ _ Cla Cla Cla _ Cla1 8 1 7 Car

_ _ _ _ Cla Cla ? Cla Cla _ _Cab _ 6 6 Cla _ Cla _ Cla _ Cla 5 Cla5 _ Cla

______Cla Cla Cla2 Cla2 Cla2 Cla4 Cla2? _ _ Cla10 ??Cla10 ______Cla Cla Cla Cla _Cla Cac Cac

ANTRIM PLATEAU VOLCANICS PLATEAU ANTRIM 3 9 3 3

A09-268.ai _ _Cla = _Cab Bingy Bingy Basalt Member Cla Massive porphyritic and tholeitic basalt 6 Medium-grained glomeroporphyrtic _ _ Cla = _Car Blackfella Rockhole Member Cla Agglomerate, highly weathered and 1 Interbedded basalt and agglomerate, minor intercalated sandstone 7 lateritised in places _ _ Friable cross-bedded quartz sandstone with some surface silicification Cla Cla2 8 Agglomerate _ _ _ Ferruginous sandstone, laminated Cla = Cac Laminated chert, stromatolitic in part (Mount Close Chert in WA) Cla 3 9 chert after limestone _ Sandstone, rare limestone, may represent _Cla Cla 4 Interbedded chert and sandstone 10 undifferentiated members above _Cla Grey tuffaceous sandstone with angular chert fragments near base, 5 minor dark grey chert interbeds Figure 30.3. Suggested lithostratigraphic correlation of mapped units within Antrim Plateau Volcanics in the Victoria River Region, based on surface mapping, which does not preclude the presence of other units in the subsurface (from unpublished 2000 work by JN Dunster). Unit symbols are as depicted on published mapfaces.

Geology and mineral resources of the Northern Territory 30:4 Special publication 5 Kalkarindji Province

a 800 Cambrian Roberts (1965) similarly interpreted structures in the Limestone correlative Buckingham Bay Sandstone (Arafura Basin) as Skolithos sp. However, Haines in (Rawlings et al 1997) reinterpreted these structures as being abiogenic GHZDWHULQJ IURP ÀXLGL]HG VDQG  DQG VXJJHVWHG WKDW WKH 700 sandstones containing these structures are more likely to EH1HRSURWHUR]RLFLQDJH In general, the Antrim Plateau Volcanics are b Cambrian unconformably overlain by early middle Cambrian Limestone carbonate units: Headleys Limestone of the Ord Basin 600 600 (Mory and Beere 1988); Montejinni Limestone of the Wiso Basin (Randal and Brown 1967); and Tindall Limestone of the Daly Basin (Kruse et al 1994). In Katherine, palaeontological evidence indicates that the Tindall 500 500 Limestone can be referred to the late Ordian stage of the Australian middle Cambrian (Kruse et al 1994, Laurie 2006). The Helen Springs Volcanics (Noakes and Traves 400 400   DUH H[SRVHG DV XQFRQIRUPDEOH YDOOH\ ¿OOV RQ 3URWHUR]RLFURFNVWRWKHHDVWRIWKH7HQQDQW5HJLRQ and also occur extensively in the subsurface in the northern and central Georgina Basin (Kruse 2008). The 300 volcanics are synonymous with the former Peaker Piker Stratigraphic height (m) Stratigraphic height (m) 300 Volcanics (Kruse in Rawlings et al 2008); these outcrop in the northeastern Georgina Basin, and unconformably RYHUOLH VDQGVWRQH DQG PXGVWRQH RI WKH 0HVRSURWHUR]RLF South Nicholson Group (South Nicholson Basin) and 200 200 sedimentary rocks of the McArthur Basin. The Helen Springs Volcanics are disconformably overlain by the middle Cambrian Gum Ridge Formation, Wonarah Formation and Top Springs Limestone of the Georgina Basin (Randal et al 1966, Kruse et al 2010). A sedimentary 100 100 unit containing peperite, the Muckaty Sandstone Member forms the base of the Helen Springs Volcanics to the east of the Tennant Region in HELEN SPRINGS (Hussey et al 2001). The Helen Springs Volcanics are 9 m thick in cored 0 0 drillhole NTGS96/1 in central HELEN SPRINGS (Kruse Precambrian Precambrian 1996, Hussey et al 2001), and the unit reaches a maximum thickness of 156 m in cored drillhole AY06DD01 in massive basalt vesicular basalt southeastern ALROY (Kruse 2008). The former Peaker porphyrtic basalt brecciated basalt

Piker Volcanics are 16 m thick in drillhole DD83SC1 in unconformity WALHALLOW (Dunster 2009). Close to the Queensland–Northern Territory border, Darwin the Colless Volcanics (Carter and Öpik 1961) form small exposures on the margins of the eastern Georgina Basin in

LAWN HILL, western Queensland. This unit consists of Kalkarindji amygdaloidal basalt and other tholeiitic lavas outcropping outcrop extent over only a few square kilometres at the southern end of the Constance Range, where they unconformably overlie the South Nicholson Group. The volcanic rocks are Kununurra unconformably overlain by the Thorntonia Limestone of the Georgina Basin. ,QWKH2I¿FHU%DVLQ FHQWUDO:HVWHUQ$XVWUDOLD WKH Purnululu stratigraphic section Table Hill Volcanics are conformably underlain by the Golden Downs Wahlgu Formation and Lungkarta Formation, and overlain stratigraphic section by the Paterson, Lennis and Wanna Formations. The A07-164.ai NT WA Boondawari dolerite (MacDonald et al 2005) is a feeder dyke to the volcanic suites. The former Kulyong Formation Figure 30.4. Stratigraphic sections for Kalkarindji Suite. (a) East– west transect at Purnululu National Park, DIXON RANGE, and LQWKH2I¿FHU%DVLQZHVWHUQFHQWUDO6RXWK$XVWUDOLD QRZ (b) east–west transect at trigonometric station J32 of Hardman superseded by the Table Hill Volcanics) is underlain by the   *25'21 '2:16 :HVWHUQ $XVWUDOLD PRGL¿HG DIWHU Trainor Hill Sandstone and overlain by the Mount Chandler Glass 2002).

Geology and mineral resources of the Northern Territory 30:5 Special publication 5 Kalkarindji Province

Sandstone. Possible early Cambrian basaltic rocks in Figure 30.1), which intrudes Palaeoproterozoic rocks of the association with known tuffs have also been observed by .LQJ/HRSROGRURJHQLFEHOW J Dunster in petroleum exploration drillholes to the extreme HDVWRIWKH2I¿FHU%DVLQ 6$ ZLWKLQWKHHDUO\&DPEULDQ Geochronology Cadney Park Member. More recently, geochemically similar rocks of the same age as the Kalkarindji Suite have been Bultitude (1972) provided the earliest geochronological LGHQWL¿HGLQWKHHDVWHUQ$UXQWD5HJLRQRIFHQWUDO$XVWUDOLD studies for the Kalkarindji Province and obtained K-Ar /DZOH\:KHODQet al 2010). ages of 511 ± 12 Ma and 500 ± 12 Ma, as recalculated by Eruptive centres for the Antrim Plateau Volcanics (ie Glass (2002) using the decay constants of Steiger and Jäger Kalkarindji Suite) are not easily recognisable, possibly because (1977), for the Helen Springs and former Nutwood Downs WKH YHQWV ZHUH EXULHG E\ VXFFHVVLYH ODYD ÀRZV %XOWLWXGH Volcanics, respectively. At the time the data were generated, 1976); however, swarms of small, altered and brecciated they were assumed to be erroneously young as they were dykes cut the volcanic rocks around the south-southeastern inconsistent with known stratigraphic constraints (Bultitude extremity of the Hardman Syncline (part of the Ord Basin). 1972, 1976). Hanley and Wingate (2000) obtained a U-Pb These dykes consist of angular fragments of massive to slightly 6+5,03 ]LUFRQ DJH RI  “  0D IRU WKH 0LOOLZLQGL YHVLFXODUEDVDOWLQD¿QHFKORULWLVHGEDVDOWLFPDWUL[$OWKRXJK Dolerite, a feeder dyke to Kalkarindji basalts in Western outcropping feeder dykes to the Kalkarindji province are not Australia. Glass and Phillips (2006) reported high-precision evident in the Northern Territory, First Vertical Derivative 40Ar/39Ar ages for plagioclase feldspar separates for basalts DHURPDJQHWLF LPDJHU\ &OLIWRQ   UHYHDOV D ! NP from the Helen Springs Volcanics and Antrim Plateau long structure under cover that may represent a lava river Volcanics. The data have an age range between 508 ± 2 Ma WKDWÀRZVHDVWWRZHVWDFURVVWKHZHVWHUQ1RUWKHUQ7HUULWRU\ DQG“0D ı \LHOGLQJDQDYHUDJHUDGLRPHWULFDJH (Figure 30.8). Outcropping dolerite dykes, interpreted to be of 507 ± 4 Ma, which places the Kalkarindji eruption event feeder dykes to the Kalkarindji Province, are present in the close to the early–middle Cambrian boundary (Glass and western Kimberley region of Western Australia (Hanley and Phillips 2006). The oldest age (within error) is compatible Wingate 2000, Glass 2002), the most prominent being the with the position of the volcanic rocks below the securely 250 km-long Milliwindi Dolerite (Hanley and Wingate 2000, dated Cambrian sequence 1 (Ordian) interval of Shergold et al

129°15'06"E 129°16'14"E 16°47'49"S 16°47'49"S

DARWIN

NORTHERN TERRITORY

ALICE SPRINGS A09-236.ai 0 500 m

16°56'43"S 16°56'43"S 129°15'06"E 129°16'14"E Figure 30.5*RRJOH(DUWKŒVDWHOOLWHLPDJHVKRZLQJREOLTXHYLHZRIÀDWO\LQJ.DONDULQGMLYROFDQLFVXFFHVVLRQVIRUPLQJSURPLQHQW PHVDVFDSSHGE\UHVLVWDQW%ODFNIHOOD5RFNKROH0HPEHUDJJORPHUDWHDQGYHVLFXODUÀRZWRSVGLVVHFWHGE\PRGHUQGD\VWUHDPV9LFWRULD River region, NT.

Geology and mineral resources of the Northern Territory 30:6 Special publication 5 Kalkarindji Province

 6RXWKJDWHDQG6KHUJROG  DQG/DXULH  7KH Kalkarindji Suite

DELAMERE results are in agreement with known age constraints for the 1:250 000 mapsheet Table Hill Volcanics, which include a K-Ar whole rock age Wave Hill-1 of 500 ± 14 Ma (as reported in Veevers 2000), a 207Pb/206Pb BMR drillhole zirconolite age of 504 ± 18 Ma (Stern et al 2005) and an DELAMERE 40Ar/39Ar age of 505 ± 3 Ma (Evins et al 2009). Moreover, MacDonald et al  UHSRUWHGD83E6+5,03]LUFRQ DJHRI“0D ı IRUWKH%RRQGDZDULGROHULWHDIHHGHU Delamere NORTHERN Victoria Hwy G\NHWRWKH7DEOH+LOO9ROFDQLFVORFDWHGLQWKH2I¿FHU%DVLQ Road TERRITORY Delamere-1

Petrology Victoria River WATERLOO VICTORIA RIVER DOWNS

7KH.DONDULQGMLEDVDOWVFRQVLVWRIDVHULHVRI௘±PWKLFN Victoria River Downs-3 Waterloo-2 ODYD ÀRZV RI PRVWO\ ¿QHJUDLQHG PDVVLYH EDVDOW ZLWK Buchanan Hwy FRQVSLFXRXV YHVLFXODU ÀRZ WRSV DQG OHVV FRPPRQ Waterloo-1 East Baines River Victoria River Downs-1 plagioclase-phyric basalt. The basalt mineral assemblage Victoria River Downs-2 comprises plagioclase, clinopyroxene (augite or pigeonite) rare orthopyroxene with lesser ilmenite, titanomagnetite, LIMBUNYA WAVE HILL primary and secondary quartz and K-feldspar (Glass 2002). Negri

Olivine, mica and hornblende are accessory components River Limbunya-1 (Bultitude 1971). Glass (2002) described the petrology of the River Buchanan Hwy Kalkarindji basalts in some detail and this is summarised Wave Hill-1

K H U H  7H [ W X U D O O \ W K H E D V D O W V Y D U \ I U R P H [ W U H P H O \ ¿ Q H  J U D L Q H G  Limbunya-2 050100 km aphanitic rocks to porphyritic and coarse-grained rocks Victoria A09-238.ai approaching doleritic textures. The primary phenocryst Figure 30.6/RFDWLRQRI%05VWUDWLJUDSKLFGULOOKROHV GULOOORJV and microphenocryst phases are subhedral clinopyroxene, shown in Figure 30.7) in Victoria River region. Kalkarindji Suite near-euhedral plagioclase feldspar and, in the most evolved outcrop extent shown by green areas, derived from GA 1:1M rocks, abundant quartz. Secondary phases include chlorite, JHRORJ\*,6GDWDVHW

Delamere-1 Victoria River-1 Victoria River-2 Victoria River-3 Wave Hill-1 Limbunya-2 Limbunya-1 Waterloo-1 Waterloo-2 Metres 0

20

40

60

TD=74.7 m 80

TD=91.4 m 100

120

140

TD=153.9 m 160 TD=164.6 m 180

Massive basalt 200 Amygdaloidal and Vesicular basalt 220 TD=221.0 m Agglomerate 240 Sandstone TD=243.8 m TD=243.8 m Siltstone 260

TD=269.7 m Chert 280

Limestone 300 TD=304.8 m A07-197.ai Figure 30.7/LWKRORJLFDOORJVRIVWUDWLJUDSKLFGULOOKROHVLQ9LFWRULD5LYHUUHJLRQ PRGL¿HGDIWHU%XOWLWXGH 7' 7RWDO'HSWK

Geology and mineral resources of the Northern Territory 30:7 Special publication 5 Kalkarindji Province

131.4° 131.6° 131.8° 132° 132.2°

DARWIN

16.8°

NORTHERN TERRITORY

ALICE SPRINGS

17°

17.2°

0 5 10 km

A09-237.ai Figure 30.8. First Vertical Derivative aeromagnetic image, derived from Clifton (2008), showing section of large curvilinear structure WKDWPD\UHSUHVHQWDODYDULYHUIRU.DONDULQGML6XLWHEDVDOWV:$9(+,//ZHVWHUQ1RUWKHUQ7HUULWRU\

a b

c

Figure 30.9. Scanning Electron Microscope (SEM) photomicrographs of Kalkarindji Suite basalts (from Glass  3ODJ SODJLRFODVH$Q DQRUWKLWHFRQWHQWTW] TXDUW] FS[  FOLQRS\UR[HQH LOP  LOPHQLWH PW  WLWDQRPDJQHWLWH NIVS .IHOGVSDU a) Coarse-grained Helen Springs Volcanics 0J2 ZW VKRZLQJVXERSKLWLFWRRSKLWLFWH[WXUH ,OPHQLWH RFFXUV DORQJ JUDLQ ERXQGDULHV EHWZHHQ FOLQRS\UR[HQH and plagioclase. (b $QWULP3ODWHDX9ROFDQLFV 0J2 ZW  showing ophitic texture. (c) Antrim Plateau Volcanics 0J2 ZW VKRZLQJ¿QHJUDLQHGJURXQGPDVV1RWHWZR

plagioclase compositions: An49 and An61.

Geology and mineral resources of the Northern Territory 30:8 Special publication 5 Kalkarindji Province albite, K-feldspar, quartz and titanite. Rocks that have geochemically indistinguishable (Figure 30.10). A genetic undergone hydrothermal alteration are commonly chloritic link between the Table Hill Volcanics and the Antrim Plateau DQGKDHPDWLWLFDQGKDYHDP\JGDOHV¿OOHGZLWKVHFRQGDU\ Volcanics has been further reinforced by M Gole (consultant prehnite, malachite, calcite and silica. Groundmass phases geologist, pers comm 2003), based on the evaluation of a are mostly coarse to medium-grained, ophitic to granular substantial number of geochemical analyses of the former and intergranular (euhedral plagioclase laths and subhedral unit. More recent work by Evins et al FRQ¿UPVWKLV S\UR[HQH KRZHYHULQWKHPRVWIUDFWLRQDWHG¿QHJUDLQHG 7KH.DONDULQGMLEDVDOWVDUHORZ7LWKROHLLWHV0J2ZW rocks, intersertal textures dominate due to the presence of YDOXHVDUHYDULDEOHDQGUDQJHIURPFDWRZWZLWKD IRUPHU LQWHUVWLWLDO JODVV ,QWHUVWLFHV LQ VRPH ¿QHJUDLQHG PHDQ RI FD  ZW 0J PRODU 0J 0J)H for rocks may contain late-crystallising potassic and sodic Fe2O3)H2  YDULHVIURPWRKRZHYHUYDOXHV feldspar and quartz. Scanning Electron Microscope for most basalts cluster between 65 and 50. The Kalkarindji (SEM) photomicrographs (Figures 30.9a–c) show textural EDVDOWVDUHGLVWLQJXLVKHGE\ORZKLJK¿HOGVWUHQJWKHOHPHQW petrographic relationships for the Helen Springs Volcanics (HFSE) abundances, eg low elemental abundances of Ta, P, and Antrim Plateau Volcanics. Feldspar compositions for Ti and Nb relative to the incompatible elements. The basalts all Kalkarindji rocks, range from An49 to An72 and pyroxene and dolerites further show extreme enrichment in the most compositions include high-Cr pyroxene (Cr-diopside), Ca- LQFRPSDWLEOHHOHPHQWVVXFKDV7K8DQGWKH/LJKW5DUH rich clinopyroxene (augite), pigeonite and orthopyroxene. (DUWK(OHPHQWV /5(( IDUUHPRYHGIURPQRUPDOEDVDOWLF ,OPHQLWHDQGWLWDQRPDJQHWLWHDUHFRPPRQLQWKH compositions and more similar to continental crustal .DONDULQGMLEDVDOWV,OPHQLWHW\SLFDOO\RFFXUVLQLQWHUVWLFHV compositions. These distinctive geochemical characteristics between clinopyroxene and plagioclase (Figure 30.9a). serve to distinguish the Kalkarindji basalts from all other &,3:QRUPDWLYH FDOFXODWLRQV *ODVV   UHYHDO WKDW large igneous provinces worldwide (Glass 2002). the Kalkarindji basalts range from olivine-hypersthene Platinum Group Elements (PGE) abundances are QRUPDWLYH FRPSRVLWLRQV ZLWK  ROLYLQH WR TXDUW] extremely low, in most cases below the detection limit (Glass QRUPDWLYHFRPSRVLWLRQVZLWK TXDUW]$OOEDVDOWV   DQG PD\ LQGLFDWH VXO¿GH VDWXUDWLRQ DW VRPH VWDJH LQ FRQWDLQ DERXW  QRUPDWLYH GLRSVLGH 6LOLFD VDWXUDWLRQ the basalt petrogenesis. Depletion in the PGE may indicate levels are transitional between quartz tholeiite and olivine VXO¿GH VHJUHJDWLRQ DVVRFLDWHG ZLWK FUXVWDO FRQWDPLQDWLRQ normative tholeiite. which would have resulted in the sequestering of chalcophile elements; this has implications for nickel prospectivity for Geochemistry the Kalkarindji Suite. Similar depletions in PGE patterns to .DONDULQGMLYROFDQLFURFNVRFFXULQWKH6LEHULDQ7UDSV/DUJH Geochemical signatures for the Kalkarindji Province ,JQHRXV3URYLQFHDW1RULO¶VNLQQRUWKHUQ6LEHULD HJ%UJPDQQ basalts were described in some detail by Glass (2002) and et al 1993), which is host to World-class nickel mineralisation. Glass and Phillips (2006), and the most distinctive feature for the basalts is the overall geochemical homogeneity Structure across the entire province. Glass and Phillips (2006) further demonstrated that the Antrim Plateau Volcanics and the Kalkarindji basalts are the basal unit of a number of stratigraphic equivalents (ie Helen Springs Volcanics, Palaeozoic basins across northern Australia, including the former Nutwood Downs Volcanics, former Peaker Piker northern Wiso, Daly, Bonaparte, Ord and northern Georgina Volcanics, Boondawari dolerite and Table Hill Volcanics) are Basins. Although these basins were attenuated, rifting

Helen Springs Volcanics Mg# = 60 Former Nutwood Downs Volcanics Mg# = 52 100 Former Peaker Piker Volcanics Mg# = 44 Boondawari dolerite Mg# = 59 Table Hill Volcanics Mg# = 60

Figure 30.10. Primitive-mantle normalised element abundance diagram showing range for Antrim Plateau Volcanics (green) overlain by data for 10 Antrim Plateau basalt stratigraphic FRUUHODWLYHV PRGL¿HGDIWHU*ODVVDQG

3KLOOLSV   ,QFOXGHV GDWD IRU +HOHQ Concentration / Primitive Mantle Springs Volcanics, former Nutwood Downs Volcanics, former Peaker Piker Volcanics, Table Hill Volcanics and Boondawari dolerite (feeder dyke for the Table Hill Volcanics). Normalising values from McDonough and Sun 1995. Antrim Plateau Volcanics A09-234.ai 0J  ^PRODU 0J0J)H) for 1

Fe2O3)H2 ` Cs Rb Ba Tn U K Ta Nb La Ce Sr P Nd Hf Zr Sm Ti Dy Y Yb Sc V

Geology and mineral resources of the Northern Territory 30:9 Special publication 5 Kalkarindji Province never went to completion. The basalts attain their greatest Petrogenesis thickness in the East Kimberley region, east of the Halls Creek Orogen and this led Mory and Beere (1988) and Glass Petrogenetic modeling of Kalkarindji Province basalts (2002) to suggest that this region was most likely the major by Glass (2002) established that the basalts can eruptive centre for Kalkarindji volcanism. However, given be successfully modeled by crustal contamination the dimensions of the province, an extensive dyke system for processes of a primary asthenospheric source the basalts is most likely concealed, possibly by subsequent composition. The original source magmas assimilated ODYDÀRZV %XOWLWXGH 7KH0LOOLZLQGL'ROHULWH +DQOH\ EHWZHHQ±RIW\SLFDODYHUDJH3URWHUR]RLF1RUWK and Wingate 2000, Glass 2002) and the informal Mount Australian Felsic Crust (NAFC), Glass (2002), Glass Ramsay dolerite (Glass 2002) in the southwest Kimberley et al (2006). Glass (2002) further calculated that the region are the only known exposed dyke systems interpreted Kalkarindji primary picritic melts (in equilibrium with DVSUREDEOHIHHGHUVWRWKH.DONDULQGMLEDVDOWV*ROHDQG/HH mantle olivine) segregated from their mantle source at (2006) interpreted a major NNW-trending structural axis in pressures of about 15 to 20 kbar, which is equivalent to a /,0%81<$SDUWO\GH¿QHGE\GHHSVHDWHGOLQHDUPDJQHWLF depth of 50–70 km. However, in Neoproterozoic times, anomalies as the main axis of doming, magma injection and ca 200 km-thick lithosphere would have underlain extrusion of magma. They further suggested that sites for the postulated future eruptive centre for Kalkarindji intrusion may have occurred along east-northeast-trending magmatism (see Glass 2002). Some type of tectonic structures (eg, the West Baines, Neave and Rosewood faults), process, therefore, must have substantially thinned the which they interpreted as transform faults that developed lithosphere prior to Kalkarindji magmatism. A mantle parallel to crustal extension. plume source to generate the melts is feasible, providing Although concealed under cover, the prominent Neave WKH OLWKRVSKHUH ZDV WKLQQHG SULRU WR VLJQL¿FDQW PHOW Fault (Figures 30.2a, b) and less obvious Negri Fault appear segregation. Catastrophic lithospheric delamination, WRRIIVHW$QWULPEDVDOWVLQ/,0%81<$7KHUHODWLRQVKLS accompanied by substantial asthenospheric melt between the Neave Fault and the Antrim Plateau Volcanics segregation, may be another mechanism to account for may represent any of the following: WKLV/,3 *ODVV 

1. a large structure which has offset basaltic lavas to the MINERAL RESOURCES north that have subsequently been eroded 2. a fault scarp palaeotopographic feature which Copper FRQVWUDLQHGEDVDOWLFÀRZWRWKHVRXWKRIWKHIDXOWVFDUS 3. a feeder conduit to the basalts. Work by the BMR in the 1950s and 1960s, and later by the Northern Territory Geological Survey (eg Cutovinos ,Q:$7(5/22WKH:HVW%DLQHV)DXOWDOWKRXJK et al LGHQWL¿HGZLGHVSUHDGEXWHFRQRPLFDOO\ a prominent structure, appears to displace the Antrim LQVLJQL¿FDQW FRSSHU PLQHUDOLVDWLRQ LQ WKH XSSHUPRVW Plateau Volcanics and Angalarri Siltstone by only about units of the Antrim Plateau Volcanics, near and along 100 m (Sweet 1973b). Minor displacement of the Antrim WKHFRQWDFWZLWKWKHRYHUO\LQJ+HDGOH\V/LPHVWRQHRIWKH Plateau Volcanics and the Moonlight Valley Tillite occurs Ord Basin. Some copper was also noted in the overlying on the northern extension of the Blackfella Creek Fault limestone close to the contact zone. A total of 19 recorded :$7(5/22  mineral occurrences are known in the NT (NTGS MODAT UHFRUGV DQGWKHUHDUHPDQ\PRUHLQ:$/RFDWLRQVIRU Possible link to early–middle Cambrian mass extinction selected copper occurrences in the Victoria River district are shown in Figure 30.11. High-precision 40Ar/39Ar ages, established by Glass and Extensive exploration for copper was conducted in the Phillips (2006), indicate that the Kalkarindji eruption event NT during 1968–1970 by a joint venture led by Metals occurred close to the early–middle Cambrian boundary. ([SORUDWLRQ1/7KHH[SORUDWLRQZDVWDUJHWHGWRORFDWH This timing is coincident with a major global mass large copper deposits (similar to copper mineralisation extinction event which corresponds to the Toyonian stage LQ WKH /DNH 6XSHULRU UHJLRQ RI 1RUWK $PHULFD  LQ WKH of the early–middle Cambrian (Zhuravlev and Wood 1996). Antrim Plateau Volcanics (Erskine et al  ,QWKHHDUO\ This mass extinction occurred after the rapid appearance 1970s, Amoco Minerals Australia Co, led an exploration of many marine invertebrates in early Cambrian time program to test for copper mineralisation at the Antrim (Brasier et al 1994) and the Toyonian mass extinction 3ODWHDX9ROFDQLFV±+HDGOH\V/LPHVWRQHFRQWDFW9DULRXV appears to have been pronounced for the Australian region styles of copper mineralisation were distinguished in =KXUDYOHYDQG:RRG ,QDGGLWLRQ+RXJKet al (2006) these early studies (Erskine et al 1970, Burt et al 1970, UHSRUWHGDQDEUXSWLQFUHDVHLQį34S from Georgina Basin Miguel 1974): samples at about the early–middle Cambrian boundary, which they attributed to ocean anoxia combined with ‡ Structurally controlled copper mineralisation in fault increased perturbations of oceanic sulfate. They suggested and shear zones (eg malachite and chalcocite associated greenhouse warming as a result of volcanic eruptions of with fault and shear zones at the Caves prospect). WKH.DONDULQGML/DUJH,JQHRXV3URYLQFHZDVUHVSRQVLEOH ‡ Copper mineralisation in the basal three metres of the for the collapse of early metazoan reef ecosystems during RYHUO\LQJ +HDGOH\V /LPHVWRQH FKDOFRFLWH PDODFKLWH the latest early Cambrian. and azurite).

Geology and mineral resources of the Northern Territory 30:10 Special publication 5 Kalkarindji Province

‡ Copper mineralisation associated with secondary being used as an analogue. Work to date has focused in YHVLFOHLQ¿OOVLQEDVDOWLFÀRZWRSVRUGLVVHPLQDWHGLQ WA and has included encouraging rock chip samples that massive basalt in the upper Antrim Plateau Volcanics FRQWDLQXSWR&XEXWGULOOLQJLQPLGGLGQRW (native copper, chalcopyrite, cuprite, chalcocite and ¿QGHFRQRPLFVL]HGGHSRVLWV 6KRX  malachite). ‡ Copper mineralisation associated with agglomerate Nickel (chalcocite, malachite associated with barite veins). ‡ Finely disseminated native copper and chalcopyrite in 7KH.DONDULQGMLÀRRGEDVDOWVKDYHEHHQFRQVLGHUHG PDVVLYHEDVDOWÀRZV HJDW%ODFNIHOOD5RFNKROHDERXW DQDORJRXVWRFRQWLQHQWDOÀRRGEDVDOWVLQRWKHUSDUWV NPVRXWKZHVWRI0RXQW%DUWRQLQ/,0%81<$  RIWKHZRUOGPRVWLPSRUWDQWO\WKHEDVDOWVDW1RULO¶VN ‡ Copper mineralisation linked with black manganiferous in Russia, which are host to large Ni-Cu-PGE deposits. limestone mounds of possible fumarolic origin (hot Several companies have used this analogy as the basis for seeps). a conceptual exploration model targeting nickel in feeder systems to the Antrim Plateau Volcanics (eg Gole and The best documented copper prospect located during /HH +RZHYHUGULOOLQJWRGDWHKDVIDLOHGWRORFDWH these exploration activities, Caves (Figure 30.11), is suitable feeders or nickel of economic grade. ORFDWHGLQ/,0%81<$DQG(UVNLQHet al (1970) reported DUHVRXUFHRIDERXWWRIRUHDYHUDJLQJ±&X FOG BAY DARWIN ALLIGATOR RIVER The highest grade mineralisation is controlled by a series TIMOR Darwin So uth Alligator R. of faults in agglomerate of the Antrim Plateau Volcanics SEA QHDUWKHFRQWDFWZLWKWKH+HDGOH\V/LPHVWRQH7KHIDXOWV at the prospect may be related to the northwest-trending, steeply dipping Negri Fault, which displaces the Headleys CAPE SCOTT PINE CREEK MOUNT EVELYN /LPHVWRQHMXVWWRWKHVRXWK7KHPDLQRUHPLQHUDOVDUH malachite, chalcocite and azurite (Sweet et al 1974b). JOSEPH A circular body of fumarolic (hot seep) deposits occurs BONAPARTE Daly River adjacent to the visible mineralisation. These contain GULF disseminated, but low-grade copper. PORT KEATS FERGUSSON RIVER KATHERINE Randal and Brown (1967) reported the occurrence of Stuart Hwy native copper in basalt of the Antrim Plateau Volcanics Campbells Springs from the BMR Shoeing Tool Replacement Bore, located in Fitzmaur ic 9,&725,$5,9(5'2:160F*DLQ  GHVFULEHG e River quartz-malachite-cuprite veins and native copper in Victoria

AUVERGNER DELAMERE LARRIMAH vesicular basalt near Montejinni homestead. Crowsons RIVE EP Prospect, located 11 km west of Montejinni homestead, KE River was found by W and B Crowson of Montejinni Station in the late 1960s. Native copper, cuprite, malachite, Victoria Hwy chalcocite and traces of covellite were reported from Victoria R. the Antrim Plateau Volcanics near the contact with the WATERLOO VICTORIA RIVER DOWNS DALY WATERS Matilda Creek 0RQWHMLQQL/LPHVWRQH =LPPHUPDQ6ZHHWD  Byrnes Hill 0DODFKLWHDOVRRFFXUVDVD¿QHGLVVHPLQDWLRQLQWKH East Baines R. limestone, or forms thin (up to 1 mm) veinlets following Crowsons Prospect silty laminations in the limestone. Specimens better than &XZHUHVDLGWRKDYHEHHQFROOHFWHGIURPWKHVXUIDFH LIMBUNYA WAVE HILL NEWCASTLE WATERS (Sampey Exploration Services 1968), but individual Caves Victoria R. FRVWHDQVUHWXUQHGEHVWDVVD\VRIWR&X (Sakurai 1991). Thomson (1951) reported the occurrence of nuggets Buchanan Hwy of native copper up to 4 kg in weight at Campbells BIRRINDUDU WINNECKE CREEK SOUTH LAKE 6SULQJV )(5*866215,9(5 7KHQXJJHWVUHSRUWHGO\ WOODS RFFXUUHGDVORRVHÀRDWRQWKHVXUIDFHRIWKH$QWULP Plateau Volcanics or within soil overlying this unit and A09-256.ai Darwin ZHUHWKRXJKWWRKDYHEHHQLQ¿OOLQJMRLQWVLQWKHYROFDQLF Kalkarindji Suite locality rocks. However, subsequent exploration and visits by Government geological surveys failed to relocate the site. DELAMERE 1:250 000 mapsheet No other copper nuggets were found and no disseminated copper is present in the basalt at this location. Caves The Antrim Plateau Volcanics and associated rocks Copper occurrence are currently being explored for copper in WA and NT Figure 30.11/RFDWLRQVRIFRSSHUSURVSHFWVLQWKH9LFWRULD5LYHU E\2UG5LYHU5HVRXUFHV/LPLWHG6XSOHMDFN3W\/WGDV region, NT. Kalkarindji Suite outcrop extent shown by green their Copper Flats Project. The Michigan Copper Belt is DUHDVGHULYHGIURP*$0JHRORJ\*,6GDWDVHW

Geology and mineral resources of the Northern Territory 30:11 Special publication 5 Kalkarindji Province

Barite Although the presence of bitumen appears to be widespread in this region, target generation for bitumen seams within Pods and veins of barite in the Antrim Plateau Volcanics WKHEDVDOWLVGLI¿FXOW are commonly associated with quartz and calcite (Sweet et al 1974b). Several of the largest deposits have been Gemstones and semi-precious minerals evaluated for possible use as a weighting agent for drilling mud. The poor colour quality generally precludes other Amethyst, smoky quartz, blood red quartz locally called industrial uses. µMDVSHU¶SUHKQLWHDJDWHDQGFDOFLWHDUHFRPPRQLQ ,Q /,0%81<$ WKH Bingy Bingy Basalt Member vesicular basalt of the Antrim Plateau Volcanics (Traves contains a resource of barite occurring as lenticular lodes. 1955, Sweet et alE%XOWLWXGH2¶%\UQH 7KH  NPORQJ /HHV &UHHN /RGH FRQWDLQV DQ HVWLPDWHG 6XWWRQ'XQVWHU 7KHVHVHFRQGDU\LQ¿OO WDQGWKHNPORQJ:HVWHUQ)RUUHVW&UHHN/RGH minerals occur as geodes and amygdales. contains 261 039 t to a depth of 20 m. This material meets Dunster (2005) described specimen-quality amethyst WKH $3, VSHFL¿FDWLRQ IRU 6* IRU XVH LQ GULOOLQJ &RUQLVK (Figure 30.13) that has been collected since the 1950s and 1988). A barite deposit at Mathison Creek (FERGUSSON was mined on a small scale. One such mine, located 20 km 5,9(5 ZDVHYDOXDWHGE\1RUPDQG\,QGXVWULDO0LQHUDOV VRXWKZHVWRI&DP¿HOG6WDWLRQRSHUDWHGIRUVHYHUDOZHHNV /LPLWHGLQWKHODWHV,WLVFXUUHQWO\KHOGE\8QLPLQ during 1993 and subsequently closed. At this locality, an $XVWUDOLD/WGDQGWKHUHLVQRSXEOLFO\DYDLODEOHLQIRUPDWLRQ open joint up to 0.5 m wide, striking 205º and dipping $GHSRVLWQHDU.LUNLPELH

DQGFRQWDLQHG%D6247KH:HVWHUQ/RGHLVRQO\P faceting-grade amethyst was recovered from a mineral ORQJ$EXONVDPSOHIURPWKLVVHFRQGORGHKDGDVSHFL¿F claim in the Victoria River Downs area. Amethyst also 3 gravity of 4.54 g/cm DQGFRQWDLQHG%D624 (Willis RFFXUVNPZHVWRI/LPEXQ\D6WDWLRQDQGVRPHRIWKH and Newton 1975). Total production from the two lodes was larger lined amygdales from this location have been sold as 35 000 t, but only the top 4–5 m of lode material was mined. mineralogical specimens (Dunster 2005). The estimated resource was 32 800 t per vertical metre /RZWRPHGLXPJUDGHJHPTXDOLW\SUHKQLWH Figure 30.14a) (Mendum 1972) and a total barite resource was estimated at was discovered in the Wave Hill area of the Northern Territory 475 000 t to 20 m depth (Ransom 1980). in the 1950s. During the 1960s, several local fossickers sold quantities of this material to dealers in Victoria. Some of Bitumen the prehnite was sent to Germany for carving, but nothing more was mined until the late 1990s (Dunster 2005). Two There is anecdotal evidence of widespread bitumen within companies currently hold exploration licenses and mining Antrim Plateau basalts in the Sturt Plateau region on tenements for prehnite and hope to market the best-quality the NT (Matthews 2009). Recent drilling by Dunmarra material. Bulk samples have been collected, and some (QHUJ\ 3W\ /WG LQWHUVHFWHG PXOWLSOH YHU\ WKLQ ELWXPHQ material has been carved and tumbled (Figure 30.14b) and seams within Antrim Plateau Volcanics host rocks south evaluated overseas. of Mataranka township (Matthews 2009). The bitumen YHLQ ¿OO ZDV LQWHUVHFWHG DW DERXW  P GHSWK WKH ODUJHVW vein was approximately 5 cm in thickness (Figure 30.12).

Figure 30.13. Gemstones hosted within Antrim Plateau Volcanics Figure 30.12. Chips of bitumen from drillhole SPBP 6 (photo LQ:$9(+,//17$PHWK\VWFROOHFWHGE\ORFDOIRVVLFNHU SKRWR from Matthews 2009). courtesy of A Wygralak, NTGS).

Geology and mineral resources of the Northern Territory 30:12 Special publication 5 Kalkarindji Province

Bultitude RJ, 1971. The Antrim Plateau Volcanics, Victoria River District, Northern Territory. Bureau of Mineral Resources, Australia, Record 1971/69. Bultitude RJ, 1972. The geology and petrology of the Helen Springs, Nutwood Downs and Peaker Piker Volcanics. Bureau of Mineral Resources, Australia, Record 1972/74. Bultitude RJ, 1976. Flood basalts of probable early Cambrian age in northern Australia: in Johnson RW HGLWRU  µVolcanism in Australasia.’ Elsevier Science, 1HZ

Geology and mineral resources of the Northern Territory 30:13 Special publication 5 Kalkarindji Province

Dunster JN, 2005. Gemstones and mineral occurrences Hussey KJ, Beier PR, Crispe AJ, Donnellan N and Kruse PD, in the Victoria River Region. Northern Territory 2001. Helen Springs, Northern Territory (Second Edition). Geological Survey, Technical Note 2005-010. 1:250 000 geological map series explanatory notes, Dunster JN, 2009. Exploration history and interpretation SE 53-10. Northern Territory Geological Survey, Darwin. of the Spear Creek Structure, Walhallow. Northern Jackson MJ and van de Graaff WJE, 1981. Geology of the Territory Geological Survey, Open File Company 2I¿FHU %DVLQ :HVWHUQ $XVWUDOLD Bureau of Mineral Report CR2009-0068. Resources, Australia, Bulletin 206. Dunster JN, Beier PR, Burgess JM and Cutovinos A, Jago JB, Daily B, von der Borch CC, Cernovskis A and 2000. Auvergne, Northern Territory (Second Edition). Saunders N, 1984. First reported trilobites form 1:250 000 geological map series explanatory notes, WKH /RZHU &DPEULDQ 1RUPDQYLOOH *URXS )OHXULHX SE 52-15. Northern Territory Geological Survey, Peninsula, South Australia. Transactions of the Royal Darwin. Society of South Australia 108, 207–211. Edwards AB and Clarke E de C, 1941. Some Cambrian Jenkins RJF and Hasenohr P, 1989. Trilobites and their basalts from the East Kimberley, Western Australia. trails in a black shale: Early Cambrian of the Fleurieu Journal of the Royal Society of Western Australia 26, Peninsula, South Australia. Transactions of the Royal 77–94. Society of South Australia 113, 195–203. Erskine J, Fidler RW and Gosling T, 1970. Antrim Copper -HQVHQ+,5HSRUWRQWKHFRXQWU\EHWZHHQ3LQH Project Joint Venture progress report No. 2. Metals Creek and Tanami: Rconnaissance of Arnheim (sic) ([SORUDWLRQ 1/ )UHHSRUW RI $XVWUDOLD ,QF $QJOR /DQG2EVHUYDWLRQVRQFRXQWU\EHWZHHQ3LQH&UHHNDQG $PHULFDQ&RUSRUDWLRQ $XVWUDOLD /WGNorthern Newcastle Waters. Bulletin of the Northern Territory 14. Territory Geological Survey, Open File Company Kruse PD, 1996. Helen Springs stratigraphic drilling Report CR1970-0047. 1996 – NTGS96/1 Nilly Waterhole. Northern Territory (YLQV/=-RXUGDQ)DQG3KLOLSV'7KH&DPEULDQ Geological Survey, Technical Report GS96/4. Kalkarindji large igneous province; extent and Kruse PD, 2003. Georgina Basin stratigraphic drilling and characteristics based on new 40Ar/39Ar and geochemical petrography, 1999–2002. Northern Territory Geological data. Lithos 110(1–4), 294–304. Survey, Record 2003-005. Gatehouse CG, 1983. Stratigraphic units in the Warburton Kruse PD, 2008. Georgina Basin stratigraphic drilling Basin in South Australia. Geological Survey of South 2002–2006 and petrography 2000–2007. Northern Australia, Quarterly Geological Notes 86, 5–8. Territory Geological Survey, Record 2008-001. *ODVV/0Petrogenesis and Geochronology of the Kruse PD, Maier RC, Khan M and Dunster JN, 2010. north Australian Kalkarinji low-Ti Continental Flood Walhallow-Brunette Downs-Alroy-Frew River, Basalt Province. PhD thesis, Research School of Earth Northern Territory. 1:250 000 geological map series Sciences, Australian National University, Canberra. explanatory notes, SE 53-07, SE 53-11, SE 53-15, SF 53-03. *ODVV/0%HQQHWW9&DQG3KLOOLSV'3HWURJHQHVLV Northern Territory Geological Survey, Darwin. and geochronology of the Cambrian Kalkarindji low-Ti .UXVH 3' 6ZHHW ,3 6WXDUW6PLWK 3* :\JUDODN $6 CFB Province – northern Australia. Geochimica et 3LHWHUV3(DQG&ULFN,+Katherine, Northern Cosmochimica Acta 70(18S), A204. Territory (Second Edition). 1:250 000 geological map *ODVV/0DQG3KLOOLSV'7KH.DONDULQGML&RQWLQHQWDO series explanatory notes, SE 53-09. Northern Territory )ORRG%DVDOW3URYLQFH$QHZ&DPEULDQ/DUJH,JQHRXV Geological Survey, Darwin. Province in Australia with possible links to mass /DXULH-5(DUO\0LGGOH&DPEULDQWULORELWHVIURP extinction. Geology 34(6), 461–464. 3DFL¿F2LODQG*DV%DOGZLQZHOOVRXWKHUQ*HRUJLQD *ROH0DQG/HH6$QWULP3URMHFW177KLUGSDUWLDO Basin, Northern Territory. Memoirs of the Association relinquishment report for exploration licences 22643 of Australasian Palaeontologists 32, 127–204. DQG  SHULRG HQGLQJ  $XVTXHVW /WG /DZOH\&*(DUO\ 3DODHR]RLF PD¿F PDJPDWLVP Northern Territory Geological Survey, Open File associated with intracontinental rifting in the Harts Company Report CR2005-0678. Range, central Australia. BSc (Hons) thesis, School *UDYHVWRFN',(DUO\DQG0LGGOH3DODHR]RLF of Earth and Environmental Sciences, University of Geological Survey of South Australia, Bulletin 54, Adelaide, Adelaide. 3–61. MacDonald FA, Wingate MTD and Mitchell K, 2005. Geology +DQOH\/0DQG:LQJDWH07'6+5,03]LUFRQDJH and age of the Glickson impact structure, Western Australia. for an Early Cambrian dolerite dyke: an intrusive phase Australian Journal of Earth Sciences 52, 641–651. of the Antrim Plateau Volcanics of northern Australia. 0DWWKHZV,6WXUW3ODWHDX%LWXPHQ 63% 3URMHFW Australian Journal of Earth Sciences 47, 1029–1040. )LQDO5HSRUW(/V±'XQPDUUD(QHUJ\3W\ Hardman ET, 1885. Report on the geology of the Kimberley /WGNorthern Territory Geological Survey, Open File district, Western Australia. Western Australia Company Report CR2009-0691. Parliamentary Paper 34. McDonough WF and Sun S-s, 1995. The composition of the +RXJK0/6KLHOGV*$(YLQV/=6WUDXVV++HQGHUVRQ5$ Earth. Chemical Geology 120, 223–253. and Mackenzie S, 2006. A major sulphur isotope event McGain A, 1968. Antrim copper progress report No. 1. at c. 510 Ma: a possible anoxia-extinction-volcanism 0HWDOV([SORUDWLRQ1/)UHHSRUWRI$XVWUDOLD,QF connection during the Early-Middle Cambrian Northern Territory Geological Survey, Open File transition? Terra Nova 18(4) 257–263. Company Report CR1968-0035.

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0F/HRG,50DJQHVLWHDQGGRORPLWHBureau of Bay–Gove, Northern Territory (Second Edition). Mineral Resources, Australia, Bulletin 72, 381–399. 1:250 000 geological map series explanatory Mendum JR, 1972 Limbunya, Northern Territory (First notes, SD 53-03, 04. Northern Territory Geological Edition). 1:250 000 geological map series explanatory Survey, Darwin and Australian Geological Survey notes, SE 52-07. Bureau of Mineral Resources, Organisation, Canberra. Australia, Canberra. 5DZOLQJV'-6ZHHW,3DQG.UXVH3'Mount 0LJXHO*))LQDO5HSRUWRQ([SORUDWLRQRI(/ Drummond, Northern Territory. 1:250 000 geological Northern Territory. Amoco Minerals Australia map series explanatory notes, SE 53–12. Northern Company. Northern Territory Geological Survey, Territory Geological Survey, Darwin. Open File Company Report CR1974-0041. Sakurai M, 1991. Report on exploration for copper deposits, Mory AJ and Beere GM, 1985. Palaeozoic stratigraphy exploration licence 6346, Victoria River region. Trinity of the Ord Basin, Western Australia and Northern $PEHU3W\/WGNorthern Territory Geological Survey, Territory. Geological Survey of Western Australia, Open File Company Report CR1991-0324. Report 14, 36–45. Sampey Exploration Services, 1968. Report on prospecting Mory AJ and Beere GM, 1988. Geology of the onshore authority 1780, Montejinni District, NT. Tipperary Bonaparte and Ord Basins in Western Australia. /DQG &RUSRUDWLRQ Northern Territory Geological Geological Survey of Western Australia, Bulletin 134. Survey, Open File Company Report CR1968-0048. Muir DM, 1980. Palaeontological evidence for the Early Shergold JH, Southgate PN and Cook PJ, 1988. Middle Cambrian age of the Bukalara Sandstone, McArthur Cambrian phosphogenetic system in Australia. Bureau Basin, Northern Territory. BMR Journal of Australian of Mineral Resources, Australia, Record 1988/42, 78–81. Geology and Geophysics 5, 159–160. Shou P, 2009. A renewed focus on creating shareholder Needham RS and Stuart-Smith PG, 1984. Geology of YDOXH2UG5LYHU5HVRXUFHV/LPLWHGUpdated the Pine Creek Geosyncline, Northern Territory. Roadshow Presentation released to the ASX 08/10/2009. 1:500 000 scale map. Bureau of Mineral Resources, Smith JW and Roberts HG, 1963. Mount Drummond, Australia, Canberra. Northern Territory (First Edition). 1:250 000 1RDNHV/&DQG7UDYHV'02XWOLQHRIWKHJHRORJ\ geological map series explanatory notes, SE 53-12. of the Barkly Region: in ‘Survey of the Barkly Region, Bureau of Mineral Resources, Australia, Canberra. Northern Territory and Queensland, 1947–48’. CSIRO Southgate PN and Shergold JH, 1991. Application of Land Research Series 3, 34–41. sequence stratigraphic concepts to Middle Cambrian 2¶%\UQH '  &ROOHFWLQJ PLQHUDOV JHPVWRQHV DQG phosphogenesis, Georgina Basin, Australia. BMR Journal fossils in the Antrim Plateau Volcanics. Gem and of Australian Geology and Geophysics 12, 119–144. Treasure Hunter 96, 15–16. Steiger RH and Jäger E, 1977. Subcommission on Peers R, 1969. Precambrian rocks encountered during geochronology: Convention on the use of decay drilling in the main Phaneorozoic sedimentary basins constrains in geo- and cosmochronology. Earth and of Western Australia. Geological Survey of Western Planetary Science Letters, 36, 359–362. Australia Annual Report 1967, 69–77. 6WHUQ5$)OHWFKHU,55DVPXVVHQ%0F1DXJKWRQ1- Petroconsultants Australasia, 1989. Petroleum Basin DQG*ULI¿Q%-,RQPLFURSUREH 1DQR6,06  Study, Arafura Basin. Petroconsultants Australasia 3ELVRWRSHJHRFKURQRORJ\DW ȝPVFDOHInternational 3W\ /WG Northern Territory Geological Survey, Journal of Mass Spectrometry. 244(2–3) 125–134. Report 1989-009. 6WUXFNPH\HU +,0 FRPSLOHU   3HWUROHXP *HRORJ\ Plumb KA and Roberts HG, 1965. Blue Mud Bay/Port of the Arafura and Money Shoal Basins. Geoscience Langdon, Northern Territory. (First Edition). 1:250 000 Australia Record 2006/22. geological map series explanatory notes, SE 53-07/08. Sutton P, 2003. Quartz, prehnite and associated minerals Bureau of Mineral Resources, Australia, Canberra. from the Wave Hill area, Northern Territory. Australian 3RQWLIH[,5DQG0HQGXP-5Fergusson River, Journal of Mineralogy 9(2), 73–80. Northern Territory (First Edition). 1:250 000 6ZHHW ,3 D Victoria River Downs, Northern geological map series explanatory notes, SE 52-12. Territory (First Edition). 1:250 000 geological map Bureau of Mineral Resources, Australia, Canberra. series explanatory notes, SE 52-04. Bureau of Mineral Randal MA and Brown MC, 1967. The geology of the northern Resources, Australia, Canberra. part of the Wiso Basin, Northern Territory. Bureau of 6ZHHW ,3 E Waterloo, Northern Territory (First Mineral Resources, Australia, Record 1967/110. Edition). 1:250 000 geological map series explanatory Randal MA, Brown MC and Doutch HF, 1966. The notes, SE 52-03. Bureau of Mineral Resources, geology of the Helen Springs and Beetaloo 1:250 000 Australia, Canberra. sheet areas, NT. Bureau of Mineral Resources, 6ZHHW,30HQGXP-50RUJDQ&0DQG3RQWLIH[,5D Australia, Record 1966/110. The geology of the northern Victoria River region, Ransom DM, 1980. The Barite Resources of the Northern Territory. Bureau of Mineral Resources, .LUUNLPELH

Geology and mineral resources of the Northern Territory 30:15 Special publication 5 Kalkarindji Province

7KRPVRQ %3  &DPSEHOO¶V 6SULQJV :LOOHURR  17 included sedimentary units (see Comments). Synonymy for QDWLYHFRSSHUSURVSHFW7KH=LQF&RUSRUDWLRQ/LPLWHG constituent units: Antrim Plateau Volcanics includes Great Australia. Northern Territory Geological Survey, Antrim Plateau (Hardman 1885), Antrim Plateau Basalts Open File Company Report CR1951-0001. 'DYLG $QWULP3ODWHDX%DVDOW 0F/HRG $QWULP Traves DM, 1955. The geology of the Ord-Victoria region, Volcanics (Beattie and Brown 1984) Antrim Plateau Volcanics northern Australia. Bureau of Mineral Resources, are synonymous with Nutwood Downs Volcanics (Dunn 1963; Geology and Geophysics, Australia, Bulletin 27. see Kruse in Rawlings et al 2008); Helen Springs Volcanics are Veevers JJ, 2000. Billion-year old earth history of Australia synonymous with Peaker Piker Volcanics (Smith and Roberts and neighbours in Gondwanaland. GEMOC Press, Sydney. 1963; see Kruse in Rawlings et al 2008); Table Hill Volcanics Walter MR, 1972. Stromatolites and the biostratigraphy are synonymous with Kulyong Volcanics in SA (see W Cowley of the Australian Precambrian and Cambrian. Special and R Hocking in GA Stratigraphic Names database). Papers in Palaeontology 11. Extent: Basal unit of a number of Palaeozoic basins Walter MR, Bauld J and Brock TD, 1976. Microbiology and across northern Australia, including the northern Wiso, Daly, morphogenesis of columnar stromatolites (Conophyton, Bonaparte, Ord and northern Georgina basins. Widespread 9DFHUULOOD  IURP KRW VSULQJV LQ

Geology and mineral resources of the Northern Territory 30:16 Special publication 5 Kalkarindji Province

Reference sections: Reference section 1: East–west *HRUJLQD%DVLQ .UXVH ,Q3XUQXOXOX1DWLRQDO3DUN WUDQVHFWWKURXJKWKHKLVWRULFDORULJLQDOµ*UHDW$QWULP ',;21 :$  $QWULP 3ODWHDX 9ROFDQLFV XQFRQIRUPDEO\ 3ODWHDX¶ $QWULP3ODWHDX9ROFDQLFV W\SHVHFWLRQORFDOLW\ RYHUOLH0RXQW)RUVWHU6DQGVWRQH $OEHUW(GZDUG*URXS ,Q trigonometric station J32 of Hardman (1885) GORDON 028175$06$<$QWULP3ODWHDX9ROFDQLFVRYHUOLH/DOO\ DOWNS (approximately 600 m thick) from WGS84 52K Conglomerate and in GORDON DOWNS, Antrim Plateau P(P1 ƒ 6ƒ (EDVH WR Volcanics unconformably underlies various components of P(P1 ƒ 6ƒ (WRS $QWULP Albert Edward Group. Milliwindi Dolerite and Mount Ramsay Plateau Volcanics are unconformably overlain by Headleys dolerite are interpreted as feeder dykes to the volcanic suites. /LPHVWRQHEDVDOWVXQFRQIRUPDEO\RYHUOLH$OEHUW(GZDUG Table Hill Volcanics are underlain by Wahlgu Formation Group (Glass 2002). Reference section 2: continuously FRQIRUPDEO\ DQG/XQJNDUWD)RUPDWLRQDQGDUHRYHUODLQE\ cored vertical drillhole ANTD002 through Antrim Plateau 3DWHUVRQ /HQQLV DQG :DQQD IRUPDWLRQV 7KH %RRQGDZDUL 9ROFDQLFV $XVTXHVW/WG*ROHDQG/HH :*6. dolerite (MacDonald et al 2005) is interpreted as a feeder P(P1 ƒ 6ƒ (P dyke to the volcanic suite. The former Kulyong Formation thick). Reference section 3 for Helen Springs Volcanics: LQWKH2I¿FHU%DVLQZHVWHUQFHQWUDO6RXWK$XVWUDOLD QRZ 17*6GULOOKROH$<''LQ$/52<.P( superseded by Table Hill Volcanics) is underlain by Trainor P1 ƒ 6 ƒ ( .UXVH   Hill Sandstone and overlain by Mount Chandler Sandstone. Helen Springs Volcanics occur from 99.1–155.9 m (56.8 m). Colless Volcanics overlies Mullera Formation, and underlies Reference section 4 for Table Hill Volcanics: continuously 7KRUQWRQLD/LPHVWRQHDQG&DPRRZHDO'RORVWRQH cored drillhole BMR Westwood-1, about 210 km SE of Table Structure and metamorphism: The major eruptive +LOO ƒ 6ƒ (VHH-DFNVRQDQGYDQGH*UDDII  centre is most likely in east Kimberley region of WA. Table Hill Volcanics is 71 m thick in this drillhole. ,QWUXVLYHIHHGHUG\NHV\VWHPVLQFOXGH0LOOLZLQGLDQG0RXQW Type sections of constituent formations. Antrim Plateau Ramsay dolerites (exposed) and Boondawari dolerite (not 9ROFDQLFV 6SULQJ &UHHN LQ ',;21 5$1*( FDP H[SRVHG  /DUJH FRQFHDOHG IDXOW LQ /,0%81<$ 1HDYH thick), Western Australia (see Mory and Beere 1985, p38, Fault) may be locus for volcanic eruptions. East-northeast- 1988, p10, for grid coordinates); Helen Springs Volcanics: trending structures in northwest Northern Territory may be PWKLFNLQ+(/(1635,1*6 PLQFRUHGGULOOKROH17*6 transform faults. Basalts are unmetamorphosed.  DWƒ 6ƒ (.UXVH+XVVH\et al Geochemistry +DV GLVWLQFWLYH KRPRJHQHRXV µFUXVWDO 2001); Colless Volcanics: at about GDA94 54K 216029mE OLNH¶ JHRFKHPLFDO DQG 1G LVRWRSLF VLJQDWXUH DFURVV HQWLUH P1 ƒ 6 ƒ (  LQ ZHVWHUQ /$:1 province. Characterised by low-Ti, depleted High Field +,//4XHHQVODQG &DUWHU 7DEOH+LOO9ROFDQLFVHDVW Strength Elements (HFSE) relative to other incompatible VLGHRI7DEOH+LOO ƒ 6ƒ ( LQ7$/%27:HVWHUQ elements and marked enrichment in Th relative to U (Glass Australia (see Jackson and van de Graaff 1981). 2002, Glass et al 2006, Glass and Phillips 2006). Description at type locality: Basalts are well exposed Correlation with other units: Geochemically similar over a 760 m-thick east–west stratigraphic section. Exposed URFNVRIWKHVDPHDJHKDYHEHHQLGHQWL¿HGLQWKHHDVWHUQ basal contact with Mount Forster Sandstone (Albert Edward $UXQWD5HJLRQRIFHQWUDO$XVWUDOLD /DZOH\:KHODQ *URXS FRQVLVWVRIQDUURZµEDNHG¶]RQHLQWRXQGHUO\LQJ et al 2010). Mount Wright Volcanics and Cymbric Vale VDQGVWRQH$OOWKROHLLWHVDUHUHJLRQDOO\WLOWHGFDƒWRWKH Formation (both Gnalta Group) of Gnalta Shelf, western HDVW,QGLYLGXDOVXFFHVVLYHÀRZVDUHVHSDUDWHGE\GLVWLQFWLYH New South Wales; Truro Volcanics of Stansbury Basin, YHVLFXODUÀRZWRSV)RUWKHEDVDOFDPEDVDOWVDUHPDLQO\ South Australia – all biostratigraphically dated as late early massive and medium-grained, then become more porphyritic Cambrian (Botomian stage of Siberia; Jago et al 1984, up-section. Glomeroporphyritic basalts have small localised Jenkins and Hasenohr 1989, Gravestock 1995, Kruse and H[SRVXUH IROORZHG E\ ¿QHJUDLQHG EUHFFLDWHG EDVDOW Shi in Brock et al 2000). Possibly Mooracoochie Volcanics %ODFNIHOOD5RFNKROH0HPEHU WRZDUGVWRS,JQHRXVVHFWLRQ (Gatehouse 1983), unconformable beneath middle Cambrian LVXQFRQIRUPDEO\RYHUODLQE\+HDGOH\V/LPHVWRQH2UG Kalladeina Formation of Warburton Basin, South Australia. Basin (Glass 2002). Comments 7KH XQLW GH¿QLWLRQ RI VXLWH UHFRJQLVHV WKH Relationships and boundary criteria: Antrim Plateau dominance of the igneous component relative to minor Volcanics and Helen Springs Volcanics unconformably overlie intercalated and underlying sedimentary rocks. Suite DYDULHW\RI3DODHRDQG0HVRSURWHUR]RLFWHUUDQHV

Geology and mineral resources of the Northern Territory 30:17 Special publication 5