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鈉雲霞正長岩

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鈉雲霞正長岩 (霞石正長片麻岩),標本地點:巴西Canaã Massif

鈉雲霞正長岩(英語:Litchfieldite)是一種稀有的火成岩。 它是一種粗粒、葉理狀的霞石正長岩[1],有時稱為霞石正長片麻岩片麻狀霞石正長岩[2]。Litchfieldite 由兩種長石(主要是鈉長石,但也有一些微斜長石)組成,還有霞石方鈉石鈣霞石方解石。 鎂鐵質礦物有,磁鐵礦和富含鐵黑雲母(lepidomelane)。

產狀

鈉雲霞正長岩因 於1892 年貝利在美國緬因州利奇菲爾德的發現而得名。[3][4]。 它是一種非常稀有的岩石,曾在加拿大的藍山和法國河, 挪威的索羅伊和瓦爾河,葡萄牙塞瓦代斯,Canaã[5] Boca Nova,Itajú da Colonia 和 Peixes,巴西等地被發現。

岩石學

除了礦物成特徵外,鈉雲霞正長岩尚具有以下一種或多種結構[6][7][8][9]

  • 片麻岩外觀;由於白色和鎂鐵質礦物成帶交替出現;
  • 葉理狀:由於板狀礦物(如鱗晶黑雲母)的排列,
  • 霞石等礦物的光軸平行排列。
  • 在帶狀岩體內,被含角閃石正長岩石英正長岩包圍,
  • 斜長石鈉長石)的雙片晶中斷裂和/或彎曲,
  • 砂漿結構,
  • 黑雲母具有扭結結構和彎曲的解理,
  • 呈現大布丁或分散的塊狀物,
  • 在變質帶內呈現平行於區域結構的細長體,
  • 其同位素年齡根據區域變質作用

起源

鈉雲霞正長岩的起源有兩種假設:

  1. 由構造前岩漿造成的霞石正長岩[10].
  2. 造山運動期間侵入的霞石正長岩[11].

兩種假設都認為變質作用造成像鈉雲霞正長岩的礦物和結構特徵[12].

巴西的霞石正長片麻岩

Boca Nova

迦南

托坎廷斯霞石正長岩片麻岩 (Estrela、Eldorado、Porto Nacional、Peixe)

南巴伊亞州鹼性岩

參考文獻

  1. ^ Le Maitre, R.W. (2002) Igneous Rocks - A Classification and Glossary of Terms, 2nd edition, Cambridge, Cambridge University Press, page 105. ISBN 0-521-66215-X
  2. ^ Robins, B. and Tysseland, M. (1979) Fenitization of some mafic igneous rocks in the Seiland province, northern Norway Archived 2015-09-24 at the Wayback Machine, Norsk Geologisk Tidsskrift, Volume 59 Number 1 pages 1-23, page 3. Retrieved 2015-07-20.
  3. ^ Litchfieldite and the Litchfield Sodalite Locality, Maine Geological Survey
  4. ^ Williams, Howel, Francis J. Turner and Charles M. Gilbert, Petrography, Freeman, 1954, p. 117
  5. ^ Industrial Minerals & Rocks, Society for Mining, Metallurgy, and Exploration; 7th ed. 2006, p. 661 ISBN 978-0-87335-233-8
  6. ^ Maria de Lourdes da Silva Rosa, Herbet Conceição, Moacir José Buenano Macambira, Marco Antonio Galarza, Mônica Pringsheim Cunha, Rita Cunha Leal Menezes, Moacyr Moura Marinho, Basílio Elesbão da Cruz Filho, Débora Correia
  7. ^ D. Edgar(1968)Mineralogy of a zoned replacement body from the Blue Mountain Litchfieldite, Peterborough county, Ontario. American Mineralogist 1968;53 (5-6): 1048–1053. doi:
  8. ^ DANIEL S. BARKER, Alkalic Rocks at Litchfield, Maine, Journal of Petrology, Volume 6, Issue 1, 1965, Pages 1–27, https://doi.org/10.1093/petrology/6.1.1-a
  9. ^ M. L. KEITH; Petrology of The Alkaline Intrusive at Blue Mountain, Ontario. GSA Bulletin 1939;; 50 (12_1): 1795–1826. doi: https://doi.org/10.1130/GSAB-50-1795
  10. ^ Cunha, Rita Cunha Leal Menezes, Moacyr Moura Marinho, Basílio Elesbão da Cruz Filho, Débora Correia Rios(2007 )Neoproterozoic anorogenic magmatism in the Southern Bahia Alkaline Province of NE Brazil: U–Pb and Pb–Pb ages of the blue sodalite syenites,Lithos,Volume 97, Issues 1–2,Pages 88-97,ISSN 0024-4937, https://doi.org/10.1016/j.lithos.2006.12.011
  11. ^ Edward C Appleyard,(1974)Syn-orogenic igneous alkaline rocks of eastern Ontario and northern Norway,Lithos,Volume 7, Issue 3,Pages 147-169,ISSN 0024-4937,https://doi.org/10.1016/0024-4937(74)90028-0
  12. ^ Appleyard, E.C. (1980).Mass balance computations in metasomatism: Metagabbro/nepheline syenite pegmatite interaction in northern Norway. Contr. Mineral. and Petrol. 73, 131–144 https://doi.org/10.1007/BF00371388.