File:Spinifex komatiite sills in cumulate komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 1 (46926083995).jpg
![File:Spinifex komatiite sills in cumulate komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 1 (46926083995).jpg](https://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Spinifex_komatiite_sills_in_cumulate_komatiite_lava_flow_%28Upper_Komatiitic_Unit%2C_Kidd-Munro_Assemblage%2C_Neoarchean%2C_2.711-2.717_Ga%3B_Pyke_Hill%2C_near_the_Potter_Mine%2C_east_of_Timmins%2C_Ontario%2C_Canada%29_1_%2846926083995%29.jpg/800px-thumbnail.jpg?20191205063415)
Original file (4,288 × 2,848 pixels, file size: 9.95 MB, MIME type: image/jpeg)
Captions
Captions
Summary
[edit]DescriptionSpinifex komatiite sills in cumulate komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 1 (46926083995).jpg |
Komatiite sills in the Precambrian of Ontario, Canada. (this outcrop is bleached to prevent growth of vegetation; stratigraphic up is toward the top; this is a NO HAMMER locality) Komatiites are very rare, magnesium-rich, extrusive, ultramafic igneous rocks. They are named after the Komati River Valley in South Africa, the type locality. Komatiite is an exceedingly rare type of lava. No volcano on Earth erupts this material today. Komatiites are essentially restricted to the Archean (4.55 to 2.5 billion years ago). Experimental evidence has shown that komatiite lavas, when originally erupted, were considerably hotter (~1600º C) than any modern lava type on Earth. This indicates that Earth’s mantle was much hotter than now. Other geologic evidence also indicates that early Earth’s heat flux was much higher than today’s. Komatiite lava had a very low viscosity - it could flow like an ultradense gas. This property permitted the solidification of some individual lava flows that are only 1 cm thick. The classic texture of komatiites is spinifex texture, named after clumps of long, spiky (& painful!) grasses. Komatiites with spinifex texture have short to long blades or plates of olivine mixed with smaller-scale blades of pyroxene. All Archean komatiites are metamorphosed - the original igneous mineralogy (olivine, pyroxene, minor chromite, etc.) is gone to mostly gone. Such rocks are best termed metakomatiites, but the prefix “meta-” is usually not specified in writing. Komatiites have economic significance, as many are closely associated with copper-nickel minerals (chalcopyrite & pentlandite), plus minor platinum-group elements, arsenides, bismuthides, and maybe a little gold and silver. Komatiites are a world-class source of nickel in Canada and Western Australia. The outcrop seen here is part of a stack of tectonically-tilted, nearly vertical, komatiite lava flows at Pyke Hill, Ontario, Canada. The original olivine spinifex texture is serpentinized for the most part. Pyroxene spinifex consists of small, felted needles. Cumulate-textured units are also present in these lava flows, plus knobby peridotite units and brecciated or cooling-cracked flow tops. Pyke Hill is a world-famous locality for komatiites. The rocks there are part of the Kidd-Munro Assemblage, which consists of ultramafic and mafic volcanic rocks intruded by mafic to ultramafic dikes and sill-like bodies. Minor felsic volcanic rocks are also present. Volcanogenic massive sulfide deposits occur in the Kidd-Munro Assemblage - they have been mined at the Texas Gulf Mine and the Potter Mine. Within each lava flow at Pyke Hill, the silica content increases upward. The peridotites (= lower portions of each flow) are 37 to 45% silica, while the spinifex-textured rocks (= upper portions of each flow) are 42 to 45% silica. The chromium (Cr) content ranges from 1500 to 5000 parts per million in the peridotite and spinifex-textured rocks. Nickel (Ni) content ranges from 400 to 2000 parts per million. At this particular site, komatiite sills having a coarsely-crystalline spinifex texture have intruded a relatively thick, cumulate-textured komatiite lava flow. The sills are congruent to subcongruent with lava flow bedding. The chill margins of the sills are finely-crystalline, whereas olivine crystal sizes in the lava flow itself become coarser next to the flow-sill contact. The sills are interpreted as having been intruded when the lava flow was still hot and semiconsolidated (see Houlé et al., 2010). Stratigraphy: Upper Komatiitic Unit, upper Kidd-Munro Assemblage, Abitibi Greenstone Belt, lower Neoarchean, 2.711-2.717 Ga Locality: Pyke Hill outcrop - hillside exposures on the northwestern part of Pyke Hill, east of the Potter Mine, north of Route 101, east-northeast of Matheson & south of the western end of Lake Abitibi & ~83 kilometers east of the city of Timmins, Munro Township, southern Cochrane District, eastern Ontario, southeastern Canada (vicinity of 48° 35' 55.78" North latitude, 80° 12' 00.05" West longitude) (= locality B (“Spinifex veins penetrating underlying peridotite”) on the northwestern part of Pyke Hill of Fyon & Green, 1991 - Geology and ore deposits of the Timmins District, Ontario (field trip 6), Geological Survey of Canada Open File 2161, p. 29 (figure N13).) (= stop 2.1C of Houlé et al., 2010 - Stratigraphy and physical volcanology of komatiites and associated Ni-Cu-(PGE) mineralization in the western Abitibi Greenstone Belt, Timmins area, Ontario: a field trip for the 11th International Platinum Symposium. Ontario Geological Survey Open File Report 6255, p. 36 (figure 17) & p. 37.) |
Date | |
Source | Spinifex komatiite sills in cumulate komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 1 |
Author | James St. John |
Licensing
[edit]![w:en:Creative Commons](https://upload.wikimedia.org/wikipedia/commons/thumb/7/79/CC_some_rights_reserved.svg/90px-CC_some_rights_reserved.svg.png)
![attribution](https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Cc-by_new_white.svg/24px-Cc-by_new_white.svg.png)
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
![]() |
This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/46926083995 (archive). It was reviewed on 5 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
5 December 2019
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 06:34, 5 December 2019 | ![]() | 4,288 × 2,848 (9.95 MB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via #flickr2commons |
You cannot overwrite this file.
File usage on Commons
There are no pages that use this file.
Metadata
This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.
Camera manufacturer | NIKON CORPORATION |
---|---|
Camera model | NIKON D90 |
Exposure time | 1/80 sec (0.0125) |
F-number | f/4.5 |
ISO speed rating | 200 |
Date and time of data generation | 10:26, 15 July 2012 |
Lens focal length | 35 mm |
Width | 4,288 px |
Height | 2,848 px |
Bits per component |
|
Pixel composition | RGB |
Orientation | Normal |
Number of components | 3 |
Horizontal resolution | 300 dpi |
Vertical resolution | 300 dpi |
Software used | Adobe Photoshop Elements 16.0 (Macintosh) |
File change date and time | 21:59, 12 May 2019 |
Y and C positioning | Co-sited |
Exposure Program | Not defined |
Exif version | 2.21 |
Date and time of digitizing | 10:26, 15 July 2012 |
Meaning of each component |
|
Image compression mode | 4 |
APEX shutter speed | 6.321928 |
APEX aperture | 4.33985 |
APEX exposure bias | 0 |
Maximum land aperture | 4.1 APEX (f/4.14) |
Metering mode | Pattern |
Light source | Unknown |
Flash | Flash did not fire, auto mode |
DateTime subseconds | 00 |
DateTimeOriginal subseconds | 00 |
DateTimeDigitized subseconds | 00 |
Supported Flashpix version | 1 |
Color space | sRGB |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Scene type | A directly photographed image |
Custom image processing | Normal process |
Exposure mode | Auto exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Focal length in 35 mm film | 52 mm |
Scene capture type | Standard |
Scene control | None |
Contrast | Normal |
Saturation | Normal |
Sharpness | Normal |
Subject distance range | Unknown |
GPS tag version | 2.2.0.0 |
Serial number of camera | 3562538 |
Lens used | 18.0-200.0 mm f/3.5-5.6 |
Date metadata was last modified | 17:59, 12 May 2019 |
Unique ID of original document | 2FA829FF1A15D1024EF629B8CC8F1E29 |