Potash-rich volcanic rocks from southern Spain

Mineralogical Society - Tập 36 Số 279 - Trang 364-379 - 1967
G. D. Borley1
1Department of Geology, Imperial College, London, S.W. 7

Tóm tắt

SummarySeveral restricted outcrops of potash-rich volcanic rocks occur in the Spanish provinces of Murcia and Almeria, where they form intrusive pitchstones or surface lavas among country rocks consisting of Tertiary and Quaternary sediments: the volcanic rocks include jumillites and verites from the type localities of Jumilla and Vera and it is these rocks that have been investigated. Jumillites are basic lavas, sometimes coarse-grained, rich in MgO, CaO, K2O, TiO2, and P2O8, poor in SiO2, Al2O3, and Na2O and they contain important, if minor, concentrations of Cr2O3, BaO, SrO, and ZrO2. Their mineralogy is distinctive: chrome diopside, forsterite, titaniferous phlogopite, kataphorite, and sanidine, with rare leucite. Verites, typically, are black pitchstones or pitchstone breccias that range from basic to acid in composition ; they are more variable in their chemistry than jumillites, but in part this variation might be due to introduction of silicate and carbonate into some of the verites during extensive hydrothermal alteration, which has undoubtedly affected their initial chemistry. Mineralogically, verites are simpler than jumillites and have fewer phenocrysts: forsterite, some diopside, phlogopite, and, occasionally, leucite. Certain mineralogical and compositional similarities of jumillites and verites suggest they may have originated from the same type of parental magma. Their mineralogy and chemistry also relate the jumillites and verites to phlogopite-bearing potash-rich volcanics from East Africa, America, and Australia and it seems possible that all these rocks might have a common parent in mica peridotite or mica pyroxenite.

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Tài liệu tham khảo

Williams (A. F.) , 1932. Genesis of the Diamond, London.

10.2475/ajs.s4-4.20.115

10.1130/GSAB-47-111

Hague, 1889, Amer. Journ. Sei., ser. 3, 38, 43

10.1144/GSL.JGS.1940.096.01-04.04

10.1130/GSAB-50-1043

Holmes (H.) , 1952. Trans. Edin. Geol. Soc, vol. 15 (Campbell vol.), p. 187.

Holmes, 1936, Trans. Geol. Soc. S. Africa, 39, 379

Fuster (J. M.) and Pedro (F. DE) , 1953. Publ. No. 20 Estudios Geol. Inst. Lucas Mallada de Invest. Geol., p. 477.

10.1016/0016-7037(57)90032-7

Wade, 1937, Rep. Australian Assoc. Adv. Sci., 23, 93

Harvey, 1940, Journ. Roy. Soc. New South Wales, 74, 419, 10.5962/p.360310

10.1017/S0016756800089718

Osann (A. Von) , 1906. Rosenbusch. Festschr., Stuttgart, p. 233.

Holmes (H.) and Harwood (H. F.) , 1937. Geol. Surv. Uganda, Mere. 111, Pt. 11.

10.1130/GSAB-51-887

10.1080/00167615908728501

Rittmann, 1933, Zeits. Vulk., 15, 8

Washington (H. S.) , 1903. The chemical analysis of rocks. New York.

Holmes, 1950, Amer. Min., 35, 772

10.2475/ajs.s5-14.81.173

Washington (H. S.) , 1917. U.S.G.S. Prof. Paper 99.

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Mineralogical Society

Tập 36 Số 279

364-379

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