Geodiversity Research Centre, Australian Museum, Sydney, NSW 2010, Australia.

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1 Cumulate-rich xenolith suite in Late Cenozoic basaltic eruptives, Hepburn Lagoon, Newlyn, in relation to western Victorian lithosphere F. L. SUTHERLAND 1, J. D. HOLLIS 2, W. D. BIRCH 3, R. E. POGSON 1 AND L. R. RAYNOR 4# 1 Geodiversity Research Centre, Australian Museum, Sydney, NSW 2010, Australia. 2 Australian Museum, Sydney, NSW 2010, Australia. 3 Department of Mineralogy, Museum of Victoria, PO Box 666E, Melbourne, Vic. 3001, Australia. 4 Department of Geology & Geophysics, University of Sydney, Sydney 2006, Australia. SUPPLEMENTARY PAPERS Australian Journal of Earth Sciences (2004) 51, *Appendix 1 and Tables 9-15 [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's website ( or from the National Library of Australia's Pandora archive ( Corresponding author: lins@austmus.gov.au # Died 12 November APPENDIX 1: MICROSCOPE DESCRIPTIONS OF XENOLITH TYPES. Table 9 Representative mineral analyses (wt%), websterites. Table 10 Representative mineral analyses (wt%), clinopyroxenites. Table 11 Representative mineral analyses (wt%), gabbro/basalt. Table 12 Representative mineral analyses (wt%), feldspathic norite. Table 13 Representative mineral analyses (wt%), altered granulite. Table 14 Representative mineral analyses (wt%), metaperidotites. Table 15 Representative mineral analyses (wt%), melt pockets in cumulates. 1

2 APPENDIX 1. MICROSCOPE DESCRIPTIONS OF XENOLITH TYPES. Abbreviations: cpx clinopyroxene, opx orthopyroxene, ol olivine, spl spinel, plag plagioclase, ilm ilmenite. PYROXENITIC ASSEMBLAGES Websterites (HL4, HL6). Medium- to coarse-grained, with granular to embayed cpx and opx intergrowths, (pale green to yellow pleochroism) with some laminar (HL4) or vermicular (HL6) exsolution. Olivine-bearing websterites (HL5A, HL8, HLB). Pale pink to green pleochroic cpx up to 5mm (simple twinning, slight zoning, some broad straining and thin opx exsolution) partly encloses opx (faint green to yellow pleochroism) up to 3mm and opaque spl, with largely iddingsitised ol as sparse interstitial grains and inclusions. Fluid alterations occur along grain boundaries and in nests and trains of inclusions in pyroxene grains, accompanied by spongy resorption. Spinel ± olivine websterites (HL2, HL9, HL11). Similar to olivine websterites, but with larger spl and iddingsitised ol up to 3mm. Spongy resorption of cpx and sparse dark glassy interstitial melt with elongate iddingsitised ol and plag blades up to 1mm. Spinel ± olivine clinopyroxenite (HL5B). Similar to spinel-olivine websterites, but cpx dominates over minor opx (<5%). The cpx shows irregular strain and fluid resorption along boundaries. 2

3 Olivine-clinopyroxenite (E12144). Medium-grained, pale brown euhedral to subhedral cpx, with dark, partly reacted borders. Sporadic subhedral ol is embayed against cpx along marginal alterations. Sparse interstial glass contains skeletal plag and ilm. Spinel-clinopyroxenite (E12178). Medium- to coarse-grained, with cpx up to 3mm, intergrown with sporadic opaque spl up to 5mm. The cpx (pale mauve to yellow brown pleochroism) shows patchy, abrupt zoning while spl shows rims with formation of elongate iddingsitised ol. Garnet clinopyroxenite (E12143). Medium-grained, with near-equal cpx and opaque, euhedral to anhedral inhomogeneous 'garnet' altered to fine-grained spl and feldspar mosaics with rare interstitial zoned plag (<5%) and small rounded spl grains. The cpx shows aligned secondary amphibole, typical of micro-fracture alterations. FELDSPATHIC ASSEMBLAGES Gabbro (HL1). Medium- to coarse-grained, intergrown cpx, plag and accessory opaque spl are invaded by partially crystallised melt. Pale brown cpx up to 6mm intergrow with and include cpx, plag and anhedral spl up to 2 mm. Some plag grains show irregular sutured contacts. Pockets of melt contain skeletal iddingsitised ol, plag, sieved pyroxene and abundant opaque iron oxides and patches of devitrified glass. Micro-gabbronorite (HL3). Fine- to medium-grained, with abundant, pleochroic pale brown to pale yellow opx and sporadic pale grey cpx up to 0.8mm, intergrown with and 3

4 enclosed by plag up to 2 mm long. Plag grains show serrated to irregular intergrowths, zoning and carlsbad-albite-pericline twinning. Sparse opaque iron oxide grains reach up to 0.3mm. Feldspathic micro-norite (E12145). Medium-grained, dominantly plag, containing pale brown opx and rare large cpx that encloses opx, with sporadic areas of thin, wavy multiple laminated cpx and spl exsolution and scattered, part-crystallised interstitial melt. Norite (E12179). Medium- to coarse-grained, strongly zoned plag up to 5mm, partly intergrown with brown opx up to 3mm and interspersed with opaque iron oxides. Fluid inclusions form trails through the grains, with irregular invasions of partly recrystallised melt. Garnet granulite (E12180). Granular and partly recrystallised cpx, opx, plag and opaque spl up to 3mm accompany euhedral to embayed crystals up to 10mm, composed of finegrained pyroxene-feldspar-opaque oxide recrystallisations typical of altered garnet. The primary pyroxenes and spinels include apatite while feldspar includes rare small biotite. The pyroxenes are pleochroic from green to brown and plag shows some strain extinction. The altered garnet has opaque iron oxide rims, borders of radiating acicular crystals, and fine grained interior mosaics of variably pleochroic opx, plag and opaque oxides. The latter form larger clusters and scattered grains. The cpx shows intense brown to green pleochroic cores. Veins and infiltrations of vesicular, partly glassy and oxidised melt cut across primary and altered grains. META-PERIDOTITE ASSEMBLAGES 4

5 Spinel lherzolite (HL7). Coarse-grained, granular mosaic of ol, opx and cpx up to 6mm, which exhibit strain features. Subordinate interstial anhedral chromian spl forms grains up to 0.3mm. Metasomatised spinel lherzolite (HL10). Medium-grained, porphyroclastic-like mosaic, with larger ol, opx and cpx up to 4mm and finer grained neoblastic areas with well-developed triple point structures. Ol shows broad strain zoning and dislocations. Spl forms anhedral to amoeboidal interstitial grains up to 0.4mm. BASALTIC ASSEMBLAGES Host olivine basalt (HLH). Fine-grained vesicular porphyritic olivine-basalt with a range of micro-xenoliths and xenocrysts. Ol phenocrysts and glomerophenocrysts up to 2mm across are partly to completely altered to iddingsite. A fluidal groundmass is rich in zoned plag microliths and has a crypto-crystalline to darkish glassy matrix. The micro-xenoliths include mortar-textured quartz, quartzite, quartz-bearing argillites and different basalts. One basalt is a vesicular ol-bearing glassy basalt resembling a quenched early phase of the host. Other coarser grained basalts include iddingsitised ol basalts and hawaiites. Xenocrysts include cpx and ol-bearing opx derived from pyroxenites. Hawaiite (HL12). Fine- to medium-grained, partly vesicular, with euhedral to subhedral ol and cpx up to 1mm, intergrown with coarser plag up to 1.5mm and ilmenite blades up to 0.8mm. The ol is much altered to hematite, the cpx shows sector twinning and the plag is strongly zoned and twinned with sodian twin compositions. 5

6 Feldspathic hawaiite (DR16765). Medium-grained, coarser variant of hawaiite (HL12), with prominent zoned plag (up to 2mm) intergrown with clustered ol (largely iddingsitised ) and cpx (up to 0.8mm), and an intergranular groundmass with bladed to granular opaque oxides. Porphyritic hawaiite (DR16766). Phenocrysts of zoned plag (up to 1.5mm) form 15% of the rock, with scattered euhedral to corroded ol (8%, up to 0.8mm) and cpx (3%, up to 0.5mm), in a fine-grained groundmass with thin blades and grains of opaque oxides (up to 0.3mm). 6

7 Table 9 Representative mineral analyses (wt%), websterites Rock Type Ol -bearing websterite Spinel websterite Spinel websterite Sample No. HL5A HL2 HL11 Mineral Cpx Opx Cpx Opx Spl Cpx Opx Spl SiO TiO Al 2 O Fe 2 O FeO MnO MgO CaO Na 2 O Cr 2 O NiO Total Fe 2 O 3 and FeO values based on stoichiometric assignment Mg Fe Ca Ti Mg/(Mg+Fe 2+ )

8 Table 10 Representative mineral analyses (wt%), clinopyroxenites Rock Type Spinel clinopyroxenite Olivine clinopyroxenite Garnet clinopyroxenite Sample No. HL5B E12144 E12143 Mineral Cpx Spl Cpx Ol Cpx Gt SiO TiO Al 2 O Fe 2 O FeO MnO MgO CaO Na 2 O Cr 2 O NiO Total FeO 3 and FeO values based on stoichiometric assignment Mg Ca Fe Ti 2.4 Mg/(Mg+Fe 2+ )

9 Table 11 Representative mineral analyses (wt%), gabbro/basalt Rock Type Gabbro Micro-gabbronorite Basalt Sample No. HL1 HL3 HL12 Mineral Cpx Pl Cpx Opx Pl Ilm Cpx Pl SiO TiO Al 2 O Fe 2 O FeO MnO MgO CaO Na 2 O K 2 O BaO Cr 2 O NiO Total Fe 2 O 3 and FeO values are based on stoichiometric assignment Mg Fe Ca Na K Ti 44.9 Mg/Mg+Fe 2+ ) An/(An+Ab)

10 Table 12 Representative mineral analyses (wt%), feldspathic norite Rock Type Spinel-bearing feldspathic norite Sample No. E12145 Mineral Pl* Opx Opx* in Cpx* Spl Cpx*- Spl*ex Cpx SiO TiO Al 2 O Fe 2 O FeO MnO MgO CaO Na 2 O K 2 O BaO 0.01 Cr 2 O NiO Total Fe 2 O 3 and FeO values are based on stoichiometric assignment * averaged analyses Mg Fe Ca Na 36.5 K 0.6 Mg/(Mg+Fe 2+ ) An/(An+Ab)

11 Table 13 Representative mineral analyses (wt%), altered granulite Rock Type Two-pyroxene garnet granulite Sample No. E12180 main phases Garnet alteration phases Mineral Cpx Opx Pl Opx* Al-Opx Spl Usp Pl SiO TiO Al 2 O Fe 2 O FeO MnO MgO CaO Na 2 O K 2 O Cr 2 O NiO Total Fe 2 O 3 and FeO values are based on stoichiometric assignment. * Averaged analysis Mg Fe Ca Na K Ti Mg/(Mg+Fe 2+ ) An/(An+Ab)

12 Table 14 Representative mineral analyses (wt%), meta-peridotites Rock Type Spinel lherzolite (more magnesian) Spinel lherzolite (less magnesian) Sample No. HL7 HL10 Mineral Ol Opx Cpx Spl Ol Opx Cpx Spl SiO TiO Al 2 O Fe 2 O FeO MnO MgO CaO Na 2 O Cr 2 O NiO Total Fe 2 O 3 and FeO values based on stoichiometric assignment Mg Fe Ca Cr Mg/(Mg+Fe 2+ )

13 Table 15 Representative mineral analyses (wt%), melt pockets in cumulates Rock Type Iddingsitised ol. basalt glass Iddingsitised ol basalt glass Sample No. HL2 (spl) websterite (HL1) (gabbro) Mineral Pl Usp Ol Gl Pl Cpx Ol Gl SiO TiO Al 2 O Fe 2 O ) ) ) ) FeO ) 19.72) ) 13.28) MnO MgO CaO Na 2 O K 2 O BaO Cr 2 O NiO Total Fe 2 O 3 and FeO values are based on stoichiometric assignment Mg Fe Ca Na K Ti

Igneous petrology EOSC 321 Laboratory 1: Ultramafic plutonic and volcanic rocks

1 Igneous petrology EOSC 321 Laboratory 1: Ultramafic plutonic and volcanic rocks Material Needed: a) Microscope, b) Glossary of rock names and textures (see Pages 24-25 and 43 of Winter); c) Lab1 Manual