Australia. Australian Journal of Earth Sciences (2002) 49,

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1 Fohn lamproite and a possible Late Eocene pre-miocene diatreme field, Northern Bonaparte Basin, Timor Sea* J. D. GORTER 1 AND A. Y. GLIKSON 2 1 Agip Australia Limited, 40 Kings Park Road, West Perth, WA 6005, Australia. 2 Research School of Earth Sciences, Australian National University, ACT 0200, Australia. SUPPLEMENTARY PAPERS Australian Journal of Earth Sciences (2002) 49, * Appendix 1 and Tables 2 7 [indicated by an asterisk (*) in the text and listed at the end of the paper] are Supplementary Papers; copies may be obtained from the Geological Society of Australia website ( Corresponding author: john.gorter@agipenergy.com.au Appendix 1 Analytical methods, accuracy and precision. Table 2 XRFF analyses of Fohn 1 samples m and m depth. Table 3 Fohn 1 cuttings, area-scanning analyses, including specification of area dimensions, excluding volatiles and undetermined trace components. Table 4 ICP-MS and ICP-AE siderophile trace elements and platinum group element composition of Fohn 1 cuttings compared with element abundances in west Kimberley phlogopite lamproites (Jaques et al. 1986). Table 5 Electron probe EDS analyses of primary phases from Fohn 1 lamproite cuttings: (a) Ca Na amphibole; (b) richterite amphibole; (c) phlogopite; (d) ilmenite; (e) priderite; (f) apatite. Table 6 Electron probe EDS analyses of clay minerals in Fohn 1 lamproite cuttings. Table 7 Composition of analcite pseudomorphs after leucite.

2 APPENDIX 1 ANALYTICAL METHODS, ACCURACY AND PRECISION X-ray fluorescence analyses: Cuttings from m and m were analysed for major and trace elements by Ulrich Senff, Geology Department, Australian National University (Table A1). Most trace elements were determined on pressed powder samples using a SPECTRO X-Lab energy dispersive XRF spectrometer. This spectrometer uses secondary targets to modify the primary tube radiation for sample excitation. The targets Al 2 O 3 and B4C are used to produce polarised radiation, thereby lowering the background levels and therefore detection limits. Elements analysed using the B4C target are Fe to Nb, Hf to W, Hg to Bi and Th. Elements analysed with the Al 2 O 3 target are Mo, Ag to La, Ce to Nd and U. A secondary Co target is used to excite K to Mn for analysis. This target only produces Co lines, which are efficient in exciting these elements. Use of this target also results in minimal background since no continuum radiation is produced. Elements Na-S are determined using a graphite target. This target reflects the Rh-L lines, which are optimal in exciting this group of elements with again minimal background. Calibration of the Spectro instrument was performed using about 130 certified reference materials prepared in duplicate and pure compounds crushed in quartz. Powders were also measured on a PW1400 wavelength dispersive XRF spectrometer for Sc, V, Cr and Co. The analyte lines for these light trace elements are more difficult to correct for overlap effects in the energy dispersive system and are therefore better determined with a wavelength dispersive spectrometer. The wavelength dispersive spectrometer can also more efficiently excite these elements, using a Cr tube for Sc, a W tube for V and Cr and a Au tube for Co. Calibration of this spectrometer is performed using pure compounds crushed in acid washed quartz.

3 ICP-MS and ICP-AE trace element analyses: Whole rock analyses for trace metals, platinum group elements and sulphur were conducted by Analabs Pty Ltd, Perth, Western Australia. No pre-analysis de-volatilisation was conducted. Cr and S were dissolved by total acid digestion (HF, HCl, HNO 3, HClO 4 ) and analysed by ICP-AE spectrometry. Ni, Co and Cu were dissolved by total acid digestion (HF, HCL, HNO 3, HClO 4 ) and analysed by ICP-MS (Method M102). Ir, Os, Pd, Pt, Rh, Ru were analysed by ICP-MS following nickel sulphide fire assay collection from 20 gram samples, followed by Aqua Regia digestion (Method F628). Accuracy and precision were monitored using standards of felsic composition (std SO4) and mafic composition (std GS2) (Table A1) as well as external referencing. Analytical batches are run with one standard per 6 samples of unknown compositions, a blank and 8 percent duplicate and replicate analyses. Precision/reproducibility is evaluated as +/- 10% for base metals at levels X50DL (detection limit) and +/-15% for the PGE elements collected by fire essay at levels 50DL. Accuracy for PGE analyses near detection limits (0.5 ppb) are evaluated at +/-1.5 ppb - rendering the data of little meaning especially where attempts at calculating ratios are concerned Table A1. Analytical detection limits and reference standard readings (Analabs Pty Ltd.) PPM Blank/detection std SO4 std GS2 limits Cr < ppm 195ppm Ni < Co < Cu < >2000 S % PPB lower detection limit std SARM7 Ir 0.5 ppb , 71.5 Os , 64 Pd 0.5 < , 1460 Pt , Rh 0.5 < , Ru 0.5 < , 429

4 SEM-EDS analytical methods: Energy dispersive spectrometry analyses (EDS) were conducted on the Jeol6400 at the Research School of Biological Studies, Australian National University, by A.Y. Glikson. The study included reconnaissance X-ray mapping at cm-scale involving semi-quantitative EDS scanning of element concentrations larger than about 0.5 percent (Brink 1993). In this method, X-ray counts are read at 15 KeV accelerating voltage, with spectra collection time of 80 seconds (~120 seconds real time) at ~8000 cps. Semi-quantitative whole-rock analysis was performed by scanning analyses over areas ranging from 40x50 microns to 140x200 microns. Spot analyses were carried with a ~1 micron-size beam. Accuracy and precision were monitored using reference standards by Astimex Scientific Limited MINM25-53 (Serial Number ). Table A2 documents replicate analyses and statistical standard deviations monitoring accuracy and precision for standard olivine, diopside, almandine garnet, albite and barite. Estimate of precision values (standard deviation of replicate within-grain analyses) for the different elements in different minerals are as follows: SiO 2 : %; Al 2 O 3 : %; MgO: %; FeO: %; MnO: 0.11% (almandine); NiO: 0.15% (olivine); CaO: %; Na 2 O: 0.07% (albite); K 2 O: 0.01 (albite); BaO: 0.48%; SO 3 : 0.24%. Estimates of accuracy, expressed in percentage of the amount present, not including abundances near detection limits, are: SiO 2 : %; Al 2 O 3 : %; MgO: %; FeO: %; CaO: %; Na 2 O: 1.1%; BaO - 0.2%; SO 3 : 1.8% (Table A2).

5 Table A2 Precision and accuracy of repeated measurements of standard minerals on the Jeol-6400 SEM/EDS. Precision - standard deviation of measurements from the mean measurement on the Jeol Accuracy - mean departure of measurements on the Jeol-6400 from the recommended value (RV) of the mineral standard, in percentage of the amount present (%OAP). Olivine standard RV precision Accuracy (5 analyses) (5 analyses) Diopside standard RV precision accuracy (5 analyses) (5 analyses) SiO ±0.15 ±2.0%oap ±0.27 ±0.40%oap TiO FeO (t) 6.51 ±0.24 ±1.3%oap 0.05 MnO MgO ±0.42 ±1.4%oap ±0.23 ±0.20%oap NiO 0.20 ±0.15 (3 analyses) CaO ±0.20 ±0.69%oap total Mineral Almandine precision Accuracy Albite precision accuracy standard RV (5 analyses) %OAP (5 analyses) standard RV (5 analyses) (5 analyses) SiO ±0.44 ±1.47%oap ±0.22 ±0.90%oap TiO 2 Al 2 O ±0.16 ±0.33%oap ±0.19 ±0.60%oap FeO (t) ±0.12 ±1.96%oap MnO 0.59 ±0.11 ±0.34%oap MgO 10.7 ±0.11 ±2.5%oaap CaO 4.2 ±0.05 ±2.95%oap 0.13 ±0.03 ±73%oap Na 2 O ±0.07 ±1.10%oap K 2 O 0.22 total Barite precision Accuracy standard (4 analyses) (4 analyses) RV BaO 65.7 ±0.48 ±0.2%oap SO % ±0.24 ±1.8%oap total 100.0

6 Table 2 XRF analyses of Fohn 1 samples m and m depth m XRF dry total % m XRF dry total % Kimberley mean olivine lamproite Kimberley mean phlogopite lamproite SiO 2 TiO 2 Al 2 O 3 FeO MnO MgO CaO Na 2 O K 2 O P 2 O 5 BaO %wt %wt %wt %wt %wt %wt %wt %wt %wt %wt %wt * S Sc V Cr Ni Cu Zn Ga Ge As Se %wt ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm m XRF m XRF < Kimberley mean olivine lamproite Kimberley mean phlogopite lamproite Rb Sr Y Zr Nb Mo Ag Cd In Sn Sb Ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm m XRF < <0.2 < m XRF <1.1 < Kimberley mean olivine lamproite Kimberley mean phlogopite lamproite Te I Cs La Ce Pr Nd Hf Ta Tl Pb Ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm m XRF <0.3 <0.9 < m XRF 5.0 < Kimberley mean olivine lamproite Kimberley mean phlogopite lamproite Bi Th U Ppm ppm ppm m XRF m XRF Kimberley mean olivine lamproite Kimberley mean phlogopite lamproite

7 Table 3 Fohn-1 cuttings area-scanning analyses, including specification of area dimensions, excluding volatiles and undetermined trace components.

8 Table 3 - scanned area analyses of Fohn 1 cuttings. High volatiles are due to clay mineral alteration and minor undertermined componen sample/analysis F690/1 F690/2 F690/3 sample/analysis F720/1 F720/2 F720/3 scan area (mm^2) 0.62x x x0.27 scan area (mm^2) 0.25x x x0.11 SiO2%wt SiO2%wt TiO TiO Al2O Al2O FeO FeO MnO MnO MgO MgO CaO CaO Na2O Na2O K2O K2O P2O P2O normallised total Volatiles, traces ~27 ~25 ~23 volatiles&traces ~18. ~20. ~16. Quartz Orthoclase Corundum Albite Orthoclase Na Meta silicate Albite Diopside Anorthite Diopside (CaMg) Diopside Hedenbergite Diopside (CaMg) Hypersthene Hedenbergite Enstatite Hypersthene Ferrosilite Enstatite Olivine Ferrosilite Forsterite Ilmenite Fayalite Apatite Ilmenite Apatite Diff. Index Diff. Index Colour Inde Colour Index Pl=Ab+An Pl=Ab+An An/(Ab+A An/(An+A Ab^=Ab Ab^=Ab+1.85Ne Q"=Q+0.3En Q"=Q+0.3En+.23Fs

9 Ol^=Ol+.7En Ol^=Ol+.7En+.8Fs Ne^=Ne+.54A Ne^=Ne+.54Ab Q^=Q"+.46Ab Q^=Q"+.46Ab mg number mg number

10 nts sample/analysis F730/1 F730/2 F730/3 sample/analysis F850/1 F850/2 scan area (mm^2) 0.34x x x0.27 scan area (mm^2) 0.2x x0.04 SiO2%wt SiO2%wt TiO TiO Al2O Al2O FeO FeO MnO MgO MgO CaO CaO Na2O Na2O K2O K2O P2O P2O volatiles&traces ~15. ~14.5 ~16. volatiles&traces ~14.5 ~12.3 SO Orthoclase wt% Quartz Albite Orthoclase Nepheline Albite Na Meta silicate Na Meta silicate Diopside Diopside Diopside (CaMg) Diopside (CaMg) Hedenbergite Hedenbergite Hypersthene Hypersthene Enstatite Enstatite Ferrosilite Ferrosilite Olivine Olivine Forsterite Forsterite Fayalite Fayalite Ilmenite Ilmenite Apatite Apatite Diff. Index Diff. Index Colour Index Colour Index Pl=Ab+An Pl=Ab+An Ab^=Ab+1.85Ne Ab^=Ab+1.85Ne Q"=Q+0.3En+.23Fs Q"=Q+0.3En+.23Fs

11 Ol^=Ol+.7En+.8Fs Ol^=Ol+.7En+.8Fs Ne^=Ne+.54Ab Ne^=Ne+.54Ab Q^=Q"+.46Ab Q^=Q"+.46Ab mg number mg number

12 F850/3 F850/4 F850/5 sample/analysis F870/1 F870/2 F870/3 F870/4 F870/5 0.17x x x0.13 scan area (mm^2) 0.5x x x x x SiO2 wt% TiO Al2O FeO MgO CaO Na2O K2O P2O ~10.7 ~10.3 ~8.6 Volatiles, traces ~15. ~12.4 ~13. ~14. ~ SO Quartz wt% Orthoclase Albite Na Meta silicate Diopside Diopside (CaMg) Hedenbergite Hypersthene Enstatite Ferrosilite Olivine Forsterite Fayalite Ilmenite Sphene Apatite Diff. Index Colour Index Pl=Ab+An Ab^=Ab Q"=Q+0.3En

13 Ol^=Ol+.7En Ne^=Ne Q^=Q"+.46A mg number

14 sample/analysis F870/6 F870/7 F870/8 scan area (mm^2) 0.33x x x0.32 SiO2 wt% TiO Al2O FeO MnO MgO CaO Na2O K2O P2O Volatiles, traces ~10.7 ~10.8 ~11.3 SrO 0.61 Orthoclase Albite Na Meta silicate Diopside Diopside (CaMg) Hedenbergite Hypersthene Enstatite Ferrosilite Olivine Forsterite Fayalite Ilmenite Sphene Apatite Diff. Index Colour Index Pl=Ab+An Ab^=Ab+1.85Ne Q"=Q+0.3En+.23Fs

15 Ol^=Ol+.7En+.8Fs Ne^=Ne+.54Ab Q^=Q"+.46Ab mg number

16 Table 4 ICP-MS and ICP-AE siderophile trace elements and Platinum Group Element composition of Fohn-1 cuttings compared with element abundances in West Kimberley phlogopite lamproites (Jaques et al, 1986). Ni Co Cr Cu S Os Ir Ru Pt Rh Pd Fohn-1 cuttings ppm Ppm ppm ppm ppm ppb ppb ppb ppb ppb ppb m m m m m m m XRF m m XRF m m m Mean Kimberley phlogopite lamproite Mean Kimberley olivine lamproite 343 range range range range range range range range range range

17 Table 5 Electron Probe EDS analyses of primary phases from Fohn-1 lamproite cuttings: (a) Ca-Na amphibole ; (b) richterite amphibole; (c) phlogopite; (d) ilmenite; (e) priderite; (f) apatite. A. Ca-Na amphibole m m m m SiO 2 %wt TiO Al 2 O FeO Fe 2 O MgO CaO Na 2 O K 2 O total Cations Sum per 24 Ox B. Titaniferous richterite amphibole m m m SiO TiO Al 2 O FeO Fe 2 O Cr 2 O MgO CaO Na 2 O K 2 O total Cations Sum per 24 Ox C. Phlogopite m m m m SiO 2 %wt TiO Al 2 O FeO MgO CaO 1.49 Na 2 O 1.08 K 2 O dry total Cations Sum per 22 Ox D. Ilmenite m m m m m TiO MgO FeO Fe 2 O V 2 O MnO CaO Na 2 O 0.22 SiO total*

18 Cations Sum per 6 Ox *low totals reflect minor undetermined elements E. Priderite m m m m TiO FeO MgO Cr 2 O V 2 O CaO Na 2 O K 2 O BaO SiO total* Cations Sum per 16 Ox *low totals reflect minor undetermined elements F. Apatite m m m m m P 2 O 5 %wt CaO SrO Ce 2 O La 2 O Pr 2 O Nd 2 O ZrO Na 2 O K 2 O 0.43 BaO Cl F SiO Fe 2 O MgO Na 2 O 0.66 SO subtotal* Cations Sum per 26 Ox *low totals reflect volatiles and undetermined minor components. In low-total analyses only interelement ratios are considered valid.

19 Table 6 Electron probe EDS analyses of clay minerals in Fohn 1 lamproite cuttings m m m m m saponite after Fe-rich saponite Fe-rich Fe-rich Fe-rich olivine nontronite nontronite nontronite nontronite SiO 2 %wt TiO Al 2 O FeO Fe 2 O MgO CaO Na 2 O K 2 O volatiles ~13 ~8 ~20 ~21 ~11 ~12 dry subtotal* total cations per 22 Ox * * * *Fe 2 O 3 recalculated

20 Table 7 Composition of analcite pseudomorphs after leucite m m m m SiO 2 %wt Al 2 O Fe 2 O MgO 0.43 Na 2 O K 2 O volatiles ~12 ~13 ~18 ~15 dry subtotal* total cations per 7 Ox * excluding volatiles and undetermined minor components