File:Olivine gabbro (Pigeon Point Sill, Mesoproterozoic, ~1.1 Ga; Pigeon Point, Minnesota, USA) (40770721514).jpg
From Wikimedia Commons, the free media repository
Jump to navigation
Jump to search
Size of this preview: 800 × 516 pixels. Other resolutions: 320 × 207 pixels | 640 × 413 pixels | 1,024 × 661 pixels | 1,280 × 826 pixels | 2,336 × 1,508 pixels.
Original file (2,336 × 1,508 pixels, file size: 3 MB, MIME type: image/jpeg)
File information
Structured data
Captions
Summary
[edit]DescriptionOlivine gabbro (Pigeon Point Sill, Mesoproterozoic, ~1.1 Ga; Pigeon Point, Minnesota, USA) (40770721514).jpg | Olivine gabbro from the Precambrian of Minnesota, USA (public display, Geology Department, Wittenberg University, Springfield, Ohio, USA) Along the northern shore of western Lake Superior are numerous exposures of a lava flow-dominated succession called the North Shore Volcanic Group. This is equivalent to & the same age as the Portage Lake Volcanic Series of northern Michigan's Keweenaw Peninsula (<a href="https://www.flickr.com/photos/jsjgeology/albums/72157632266738191">www.flickr.com/photos/jsjgeology/albums/72157632266738191</a>). The North Shore and Portage Lake successions are ~1.1 billion years old and represent basalt lava flows, plus minor sedimentary rocks, that filled up an ancient rift valley. This old rift is the Lake Superior segment of the Mid-Continent Rift System, a tear in the ancient North American paleocontinent of Laurentia (see: <a href="https://minerals.usgs.gov/science/midcontinent-rift-minerals/images/MRS-map.png" rel="noreferrer nofollow">minerals.usgs.gov/science/midcontinent-rift-minerals/imag...</a>). Tectonic rifting started along this tear, exactly like the modern-day East African Rift Valley. Laurentia's Mid-Continent Rift System started and then stopped and was subsequently filled and buried. This ancient failed rift is now exposed on either side of Lake Superior in North America's Great Lakes. The sample shown here is from an intrusion emplaced at the same time as North Shore volcanics were being erupted. The rock is a phaneritic, mafic, intrusive igneous rock called gabbro. Gabbro has plagioclase feldspar and pyroxene. This particular specimen also has a fair amount of olivine, so it is an "olivine gabbro". Some might characterize it as a troctolite. Accompanying exhibit signage identifies it as an olivine diabase, but the crystals are too large for that - it appears to be a gabbro. The igneous body itself is a sill - a planar intrusion that parallels the country rocks. In contrast, an igneous dike is a planar intrusion that cuts across the country rocks (see: <a href="https://www.flickr.com/photos/jsjgeology/albums/72157632467411234">www.flickr.com/photos/jsjgeology/albums/72157632467411234</a>). Geologic unit & age: Pigeon Point Sill, late Mesoproterozoic, ~1.1 Ga Locality: unrecorded/undisclosed site at Pigeon Point, northern shore of Lake Superior, west of Isle Royale, adjacent to the Canadian-American border, far-northeastern Minnesota, USA |
Date | |
Source | Olivine gabbro (Pigeon Point Sill, Mesoproterozoic, ~1.1 Ga; Pigeon Point, Minnesota, USA) |
Author | James St. John |
Licensing
[edit]This file is licensed under the Creative Commons Attribution 2.0 Generic license.
- 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@N05/40770721514 (archive). It was reviewed on 21 March 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
21 March 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 | 23:25, 21 March 2019 | 2,336 × 1,508 (3 MB) | Qtz arenite (talk | contribs) | Transferred from Flickr via #flickr2commons |
You cannot overwrite this file.
File usage on Commons
There are no pages that use this file.
File usage on other wikis
The following other wikis use this file:
- Usage on da.wikipedia.org
- Usage on it.wikibooks.org
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 | Canon |
---|---|
Camera model | Canon PowerShot D10 |
Exposure time | 1/60 sec (0.016666666666667) |
F-number | f/14 |
ISO speed rating | 320 |
Date and time of data generation | 13:00, 24 March 2018 |
Lens focal length | 18.6 mm |
Image title | |
Width | 4,000 px |
Height | 3,000 px |
Bits per component |
|
Pixel composition | RGB |
Orientation | Normal |
Number of components | 3 |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
Software used | Adobe Photoshop Elements 13.0 (Macintosh) |
File change date and time | 12:14, 14 April 2018 |
Y and C positioning | Co-sited |
Exif version | 2.21 |
Date and time of digitizing | 13:00, 24 March 2018 |
Meaning of each component |
|
Image compression mode | 3 |
APEX shutter speed | 5.90625 |
APEX aperture | 7.625 |
APEX exposure bias | −0.66666666666667 |
Maximum land aperture | 4.59375 APEX (f/4.91) |
Metering mode | Pattern |
Flash | Flash fired, compulsory flash firing, red-eye reduction mode |
Supported Flashpix version | 1 |
Color space | sRGB |
Focal plane X resolution | 16,460.905349794 |
Focal plane Y resolution | 16,483.516483516 |
Focal plane resolution unit | inches |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Custom image processing | Normal process |
Exposure mode | Manual exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Scene capture type | Portrait |
Lens used | 6.2-18.6 mm |
Date metadata was last modified | 08:14, 14 April 2018 |
Unique ID of original document | A8485976058DA5F0A97A7C0BAF5E18D7 |