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Alkali basalt

A rock classification type
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08866110017271953465047.jpg
Alkali olivine basalt

Mount Kilimanjaro, Kilimanjaro Region, Tanzania
09792310017272472724892.jpg
Alkali basalt

Lake Turkana, Marsabit County, Kenya
04772420017272472734613.jpg
Alkali basalt

Lake Turkana, Marsabit County, Kenya
08866110017271953465047.jpg
Alkali olivine basalt

Mount Kilimanjaro, Kilimanjaro Region, Tanzania
09792310017272472724892.jpg
Alkali basalt

Lake Turkana, Marsabit County, Kenya
04772420017272472734613.jpg
Alkali basalt

Lake Turkana, Marsabit County, Kenya
08866110017271953465047.jpg
Alkali olivine basalt

Mount Kilimanjaro, Kilimanjaro Region, Tanzania
09792310017272472724892.jpg
Alkali basalt

Lake Turkana, Marsabit County, Kenya
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About Alkali basaltHide

A term used for a basaltic rock containing accessory foids, typically nepheline. Such rocks generally contain calcic plagioclase, augite and olivine as their main phases. Defined as a variety of basalt within TAS field B which contains normative nepheline, or as the equivalent foids-bearing basalt in field 10’ in the QAPF diagram. With increasing silica it grades into tholeiitic basalt, and with decreasing silica into basanite or tephrite.


Unique IdentifiersHide

Mindat ID:
48493
Long-form identifier:
mindat:1:1:48493:4

Classification of Alkali basaltHide

QAPF_V_10-.png

Alkali basalt appears in field 10' in the QAPF diagram.

TAS_B.png

Alkali basalt is found in field B in the TAS diagram.

Sub-divisions of Alkali basaltHide

Mineralogy of Alkali basaltHide

Essential minerals - these are minerals that are required within the classification of this rock:
Calcic plagioclaseA petrological term for plagioclase series feldspars dominant in calcium.
FeldspathoidA family of rock-forming minerals consisting of aluminosilicates of sodium, potassium, or calcium and having too ...
Feldspathoid > NephelineNa3K(Al4Si4O16)
OlivineCommonly used as a synonym for a member of the Fayalite-Forsterite Series, but more generally and properly ...
Titanium-bearing Augite(Ca,Na)(Mg,Ti, Fe,Al,)(Si,Al)2O6

Age distributionHide

Recorded ages:
Phanerozoic : 296 ± 7 Ma to 0.212 ± 0.038 Ma - based on 11 recorded ages.
Sample ages:
Sample IDRecorded ageGeologic TimeDating method
10.280 ± 0.020 to 0.212 ± 0.038 MaPleistoceneAr/Ar
22.3 ± 0.1 to 1.2 ± 0.1 MaPleistoceneAr-Ar
36.30 ± 0.20 to 5.47 ± 1.2 MaMioceneK-Ar
49.08 ± 0.29 MaMioceneAr-Ar
510.29 ± 0.04 to 9.97 ± 0.07 MaMioceneK-Ar
612.63 ± 0.17 to 0.71 ± 0.18 MaCenozoic
715 to 11 MaMioceneK-Ar
823 to 20 MaMioceneAr-Ar, K-Ar, fission track
930.0 ± 0.05 to 29.3 ± 0.4 MaOligoceneK-Ar
1067.7 ± 0.7 to 64.4 ± 0.6 MaPhanerozoicAr-Ar
11296 ± 7 MaCisuralianK-Ar
Sample references:
IDLocalityReferenceNotes
1Hilina Bench, Kilauea Volcano, Hawaii County, Hawaii, USA
Calvert, A. T., & Lanphere, M. A. (2006). Argon geochronology of Kilauea's early submarine history. Journal of Volcanology and Geothermal Research, 151(1-3), 1-18. doi.org/10.1016/j.jvolgeores.2005.07.023
2Mingxi volcanic field, Mingxi County, Sanming, Fujian, China
Ho, K. S., Chen, J. C., Lo, C. H., & Zhao, H. L. (2003). 40Ar
Ages for 2 nephelinite, an alkali olivine basalt and olivine tholeiite lava
3Mauke Island, Cook Islands
Turner, Donald L.; Jarrard, Richard D. (1982) K-Ar dating of the Cook-Austral island chain: A test of the hot-spot hypothesis. Journal of Volcanology and Geothermal Research, 12 (3). 187-220 doi:10.1016/0377-0273(82)90027-0
4Lop Buri Lava Field, Lopburi Province, Thailand
Intasopa, S., Dunn, T., & Lambert, R. S. (1995). Geochemistry of Cenozoic basaltic and silicic magmas in the central portion of the Loei
5Mururoa, Tuamotu Archipelago, Tuamotu-Gambier, French Polynesia, France
Guillou, Hervé; Guille, Gérard; Brousse, Robert; Bardintzeff, J. M. (1990) Evolution de basaltes tholeiitiques vers des basaltes alcalins dans le substratum volcanique de Fangataufa (Polynesie francaise). Bulletin de la Société Géologique de France, VI (3). p.537-549. doi:10.2113/gssgfbull.vi.3.537
6Mt Melbourne, Victoria Land, East Antarctica, Antarctica
Armienti, P., Civetta, L., Innocenti, F., Manetti, P., Tripodo, A., Villari, L. T., & Vita, G. (1991). New petrological and geochemical data on Mt. Melbourne volcanic field, northern Victoria Land, Antarctica.(II Italian Antarctic expedition). Memorie della Societ
7Hessian Depression, Kassel Region, Hesse, Germany
Wedepohl, K. H. (1982). K
8Shiting-Yinko Area, Xindian District, New Taipei City, Taiwan
Chen, C. H., Chung, S. H., Hwang, H. H., Chen, C. H., & Chung, S. L. (2001). Petrology and geochemistry of Neogene continental basalts and related rocks in northern Taiwan (III): Alkali basalts and tholeiites from Shiting-Yinko area. Western Pacific Earth Sciences, 1(1), 19-46.
9South Coast Outcrops, New South Wales, Australia
Young, R. W., & McDougall, I. (1982). Basalts and silcretes on the coast near Ulladulla, southern New South Wales. Journal of the Geological Society of Australia, 29(3-4), 425-430.
10Kutch Complex, Nakhatrana Taluka, Kutch District, Gujarat, India
Pande, K., Venkatesan, T. R., Gopalan, K., Krishnamurthy, P., & Macdougall, J. D. (1988). 40Ar-39Ar ages of alkali basalts from Kutch, Deccan volcanic province, India. Memoir-Geological Society of India, (10), 145-150.
11Côl de Péternit, Vosges Volcanic Field, Vosges, Grand Est, France
Baranyi, I., Lippolt, H.J. & Todt, W. (1976). KALIUM-ARGON-ALTERSBESTIMMUNGEN AN TERTIAEREN VULKANITEN DES OBERRHEINGRABEN-GEBIETES: II DIE ALTERSTRAVERSE VON HEGAU NACH LOTHRINGEN. Oberrheinische Geologische Abhandlungen, 25, 41-62.

Synonyms of Alkali basaltHide

Other Language Names for Alkali basaltHide

Common AssociatesHide

Associations Based on Photo Data:
2 photos of Alkali basalt associated with 'Bomb-tephra'
2 photos of Alkali basalt associated with Augite(CaxMgyFez)(Mgy1Fez1)Si2O6

Internet Links for Alkali basaltHide

References for Alkali basaltHide

Reference List:
Quick NavTopAbout Alkali basaltUnique IdentifiersClassification Sub-divisions Mineralogy Age distributionSynonymsOther LanguagesCommon AssociatesInternet Links References
 
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