Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-23T17:18:26.220Z Has data issue: false hasContentIssue false
  • English
  • Français

Layered rhyolite bands in a thick North Mountain Basalt flow: the products of silicate liquid immiscibility?

Published online by Cambridge University Press:  05 July 2018

John D. Greenough  and
J. Dostal
John D. Greenough
Affiliation:
Department of Geology, Mount Allison University, Sackville, New Brunswick, E0A 3C0
J. Dostal
Affiliation:
Department of Geology, St. Mary's University, Halifax, Nova Scotia, Canada, B3H 3C3
Get access Rights & Permissions [Opens in a new window]

Abstract

The upper 35 m of a thick (≤175 m) Early Jurassic North Mountain Basalt flow at KcKay Head contains 25 cm thick differentiated layers that are separated by 130 cm sections of basalt. The lower layers are mafic, pegmatitic, and contain thin (2 cm), fine-grained 'rhyolite' bands. Evidence that the rhyolite represents a Si-rich immiscible liquid includes: (1) textures such as fiine-grained globules of Ferich pyroxene (once Fe-rich liquid) bordering pegmatite feldspar grains; (2) structureless, microcrystalline, interstitial, polygonal patches of Si-rich minerals and similar areas of Fe-rich stilpnomelane surrounding skeletal Fe-Ti oxide grains, with bulk chemical compositions (to a first approximation), relative proportions and total modat percentages suggesting they were once Si-rich and Fe-rich glasses respectively; (3) basalt and pegmatite compositions (particularly their Fe, and Ti contents) similar to rocks known to contain immiscible liquids; (4) rhyolite major element compositions generally consistent with formation from an immiscible Si-rich liquid; (5) mineral compositions and temperature of pegmatite formation compatible with immiscibility; (6) the inability of mass balance calculations (crystal fractionation) to explain rhyolite formation unless mesostasis stilpnomelane (representing the Fe-rich liquid) is included in the caculations. If, as we suggest, these rocks are the result of immiscibility, they shed light on the incipient formation of granophyres in mafic intrusions and support liquid immiscibility as an important rock-forming process.

Keywords

rhyoliteimmiscibilitysilicate liquidNorth Mountain Basalt
Type
The Hallimond Lecture
Information
Mineralogical Magazine , Volume 56 , Issue 384 , September 1992 , pp. 309 - 318
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

Present address: Department of Geological Sciences, University of British Columbia, Okanagan College, 1000 K.L.O. Road, Kelowna, British Columbia, Canada V1Y 4X8.

References

Anderson, A.T. and Gottfried, D. (1971) Contrasting behaviour of P, Ti and Nb in a differentiated high-alumina olivine-tholeiite and a calc-alkaline andesite suite. Geol. Soc. Amer. Bull., 82, 1929–42.CrossRefGoogle Scholar
Anderson, A.T., Swinhart, G.H., Artioli, G., and Geiger, C.A. (1984) Segregation vesicles, gas filter-pressing, and igneous differentiation. J. Geol., 92, 55–72.CrossRefGoogle Scholar
Annells, R.N. (1973) Proterozoic flood basalts of eastern Lake Superior. The Keweenawan volcanic rocks of the Mamainse Point area, Ontario. Geol. Surv. Can., Paper 72-10, 51 pp.CrossRefGoogle Scholar
Aumento, F., (1966) Zeolite minerals, Nova Scotia. In Geology of Parts of the Atlantic Provinces. Geological Association of Canada, Mineralogical Association of Canada Guidebook, 71-7.Google Scholar
Bowen, N.L. (1928) The Evolution of the Igneous Rocks. Princeton University Press, Princeton, N.J. Google Scholar
Bryan, W.B., Finger, L.W., and Chayes, F. (1969) Estimating proportions in petrographic mixing equations by least-squares approximation. Science, 163, 926–7.CrossRefGoogle Scholar
Davidson, P.M. and Lindsley, D.H. (1985) Thermo-dynamic analysis of quadrilateral pyroxenes Part II, Model calibration from experiments and applications to geothermometry. Contrib. Mineral. Petrol., 91, 390–404.CrossRefGoogle Scholar
De, A. (1974) Silicate liquid immiscibility in the Deccan traps and its petrogenetic significance. Geol. Soc. Amer. Bull., 85, 471–4.2.0.CO;2>CrossRefGoogle Scholar
Deer, W.A., Howie, R.A. and Zussman, J. (1966) An Introduction to the Rock-Forming Minerals. Longman, London, 528 pp.Google Scholar
Dostal, J. and Dupuy, C. (1984) Geochemistry of the North Mountain basalt (Nova Scotia, Canada). Chem. Geol., 45, 245–1.CrossRefGoogle Scholar
Drake, L.P. (1978) Fundamentals of Reservoir Engineering. Elsevier Scientific Publishing Company, Amsterdam, 433 pp.Google Scholar
Emerson, B.K. (1905) Plumose diabase and palagonite from the Holyoka trap sheet. Geol. Soc. Amer. Bull., 16, 91–130.CrossRefGoogle Scholar
3 Freestone, I.C. (1978) Liquid immiscibility in alkali-rich magmas. Chem. Geol., 23, 115–23.CrossRefGoogle Scholar
Greenough, J.D. and Dostal, J. (in press.) Cooling history and differentiation of a thick North Mountain Basalt flow (Nova Scotia, Canada). Bull. Volcan. Google Scholar
Greenough, J.D. and Dostal, J. Jones, L.M. and Mossman, D. (1989) Petrochemical and stratigraphic aspects of North Mountain basalt from the north shore of the Bay of Fundy, Nova Scotia, Canada. Can. J. Earth Sci., 26, 1701–7.CrossRefGoogle Scholar
Greig, J.W. (1927) Immiscibility in silicate melts. Amer. J. Sci., ser. 4, 13, 1-44 & 133-54.Google Scholar
Hayatsu, A. (1979) K-At isochron age of the North Mountain basalt, Nova Scotia. Can. J. Earth Sci., 16, 973–5.CrossRefGoogle Scholar
Helz, R.T. (1980) Crystallisation history of Kilauea Iki lava lake as seen in drill core recovered in 1967-1979. Bull. Volcan., 43, 675–701.CrossRefGoogle Scholar
Jones, L.M., and Mossman, D.J. (1988) The isotopic composition of strontium and the source of the Early Jurassic North Mountain basalt, Nova Scotia. Can. J. Earth Sci., 25, 942-4.CrossRefGoogle Scholar
Lofgren, G. (1974) An experimental study of plagio-clase crystal morphology: isothermal crystallisation. Amer. J. Sci., 274, 243–73.CrossRefGoogle Scholar
McBirney, A.R. (1975) Differentiation of the Skaer-gaard intrusion. Nature, 253, 691–3.CrossRefGoogle Scholar
Papezik, V.S., Greenough, J.D., Colwell, J., and Mallinson, T. (1988) North Mountain basalt from Digby, Nova Scotia: Models for a fissure eruption from stratigraphy and petrochemistry. Can. J. Earth Sci., 25, 74–83.CrossRefGoogle Scholar
Philpotts, A.R. (1976) Silicate liquid immiscibility: its probable extent and petrogenetic significance. Amer.J. Science, 276, 1147–77.CrossRefGoogle Scholar
Philpotts, A.R. (1978) Textural evidence for immiscibility in tholeiite. Mineral. Mag., 42, 417–25.CrossRefGoogle Scholar
Philpotts, A.R. (1979) Silicate liquid immiscibility in tholeiite basalts. J. Petrol., 20, 99–118.CrossRefGoogle Scholar
Philpotts, A.R. (1982) Compositions of immiscible liquids in volcanic rocks. Contrib. Mineral. Petrol., 80, 201–18.CrossRefGoogle Scholar
Philpotts, A.R. (1990) Principles of Igneous and MetamorphicPetrology. Prentice Hall, Englewood Cliffs, New Jersey, 498 pp.Google Scholar
Philpotts, A.R. and Doyle, C.D. (1980) Immiscibility in tholeiites: a discussion. Mineral. Mag., 43, 939–40.CrossRefGoogle Scholar
Philpotts, A.R. (1983) Effect of magma oxidation state on the extent of silicate liquid immiscibility in a tholeiite basalt. Amer. J. Sci., 283, 967–86.CrossRefGoogle Scholar
Propach, G. (1976) Models of filter differentiation. Lithos, 9, 203–9.CrossRefGoogle Scholar
Puffer, J.H. and Horter, D.L. (1991) Basaltic pegmatites of the Lolo Basalt, Washington and the Watchung Basalts, New Jersey. Northeastern Section, Geological Society of America Abstracts” with Programs, 23, 118.Google Scholar
Roedder, E. (1951) Low temperature liquid immisci-bility in the system K20-FeO-Al203-SiO2. Amer. Mineral. 36, 282–6.Google Scholar
Roedder, E. (1978) Silicate liquid immiscibility in magmas and in the system K2-FeO-AlzO3-SiO2: an example of serendipity. Geochem. Cosmochim. Acta, 42, 1597–617.CrossRefGoogle Scholar
Roedder, E. and Weiblen, P.W. (1970) Lunar petrology of silicate melt inclusions, Apollo 11 rocks. In Apollo 11 Lunar Science Conference Proceedings, Geochim. Costnochim. Acta, Supplement 1, 1, 801-37.Google Scholar
Roedder, E. (1971) Petrology of silicate melt inclusions, Apollo 11 and Apollo 12 and terrestrial equivalents. Proceedings of the Second Lunar Science Conference. Ibid., Supplement 2, 1, 507-28.Google Scholar
Ryerson, F.J. and Hess, P.C. (1978) Implications of liquid-liquid distribution coefficients to mineral-liquid partitioning. Geochim. Cosmoch. Acta, 42, 921–32.CrossRefGoogle Scholar
Visser, W. and Koster van Groos, A. F. (1979) Effects of P205 and TiO2 on liquid-liquid equilibria in the system KzO-FeO-AI203-SiOa. Amer. J. Sci., 279, 970–89.CrossRefGoogle Scholar
Wager, L.R. and Brown, G.M. (1967) Layered Igneous Rocks. Oliver and Boyd, London, 588 pp.Google Scholar
Watson, E.B. (1976) Two-liquid partition coefficients: Experimental data and geochemical implications. Contrib. Mineral. Petrol. 56, 119–34.CrossRefGoogle Scholar