Subject :GEOLOGYCourse :GEOLOGY PAPER – IIKeyword : SWAYAMPRABHA
Rocks, whether sedimentary, metamorphic or igneous, tell a story. But before you can read the story you must first learn the syntax and meaning of the words that make up the language of rocks. In this article I will focus on the language of igneous rocks, and towards the end, I will talk a little…
Analysis of the surface of Venus and comparison with similar rocks on Earth constrains the amounts of water and other volatiles in the mantle of this mysterious planet.
Examining features on Earth similar to those on Mars (Earth analogs) can provide insights as to how those features formed. The Colorado Plateau in Utah has similar features to Gusev Crater (explored by Mars Exploration Rover Spirit) and Jezero Crater (future Mars 2020 rover landing site). At our field site, lava (dark gray in the picture) intruded sulfur-rich sediments. The lava provided heat to the area around it, causing groundwater to heat up and form a hydrothermal system. The hydrothermal system could have been a habitable environment on Earth and by extension on Mars.
Liquid water is required for life as we currently know it, therefore finding evidence for water has been a high priority for martian exploration. My book focuses on evidence for water and other volatile elements in the martian crust and what that means for the potential habitability of Mars.
This undergraduate petrology course surveys the distribution, chemical composition, and mineral associations in rocks of the earth's crust and upper mantle, and establishes its relation to tectonic environment. The emphasis of the course is on the use of chemistry and physics to interpret rock forming processes.
Fernando Guerra's photographs reveal a low bastion sprawling over a dust-and-red scrub landscape, built of the same volcanic rock which composes the island.
Geological rock folding in sedimentary layers on beach coastline, Croajingalong National Park, Victoria, Australia. Approx 5x3 foot section shown. Fuji GSW690II 6x9cm format, Fuji Velvia 50 film. © Ern Mainka
Magnesium-rich, calcium-poor, lilac coloured garnets have been found in the heavy mineral concentrate of the Finsch kimberlite pipe. Some of these garnets
A “thin section” of rock is a sample that is mounted to a microscope slide and cut so thin that you can see light through it. The process of creating a thin section is a blend of artistry, technology and science. The art of preparing thin sections has been critical to understanding the core samples that scientists are observing. Thin section samples allow scientists to observe minerals in rocks, their crystal structure and texture at a microscopic level. Want to revise how do geologists study rock? Follow this link to see our blog on "Studying Rock". In this blog, we're taking you into the journey of thin section photos that were captured and given by students and young professionals from Finland, Ireland, Denmark, Czech Republic and Plymouth (UK). Again our purpose is to encourage students and professionals' research by promoting "learning and scope" of Geology through our blogs. Help us to help others in learning and understanding geology. See this link that how you can contribute to Learning Geology. Note: We are using following thin section photos by having permission from their owners. If you like to use these photos, leave us a message or email us here. 1. A beautiful heart shaped hornblende in XPL (cross polarized light) view.It is a thin section of basalt with some secondary mineralization in the vesicles. Plagioclase is present in the form of black and white matrix and large phenocryst (with some zoning). Alignment of plagioclase grains is indicative of the "flow" of magma. Photo Credits: Astaley 2. Thin Section of a Biotite and Muscovite, XPL view Photo Courtesy: Laura 3. Thin Section of a Plagioclase (orthoclase) and Pyroxene, XPL Photo Courtesy: Laura 4. Eclogite in Thin Section, XPL Photo Courtesy: Laura 5. Cummulate Rock with Pyroxene and plagioclase, XPL Photo Courtesy: Laura 6. Blueschist, XPL Photo Courtesy: Laura 7. Agglomerate in a Thin Section, XPL view Agglomerates are pyroclastic igneous rocks that consist almost wholly of angular or rounded lava fragments of varying size and shape. Fragments are usually poorly sorted in a tuffaceous matrix, or appear in lithified volcanic ash. (Britannica.com) Photo Courtesy: Laura 8. Thin Section of a Pigeonite and Olivine, XPL Photo Courtesy: Laura 9. Olivine phenocryst in Basaltic Lapilli, XPL Photo Courtesy: Laura 10. Thin Section of a Gabbro, XPL Showing minerals; Pyroxene and Olivine, plagioclase and others. Learn more about Gabbro here. Photo Courtesy: Laura 11. Another beautiful thin section of a Gabbro, XPL Photo Courtesy: Laura 12. Thin Section of a Greenschist, XPL Photo Courtesy: Laura 13. Thin Section showing intrusion of rocks from magma chamber into country rocks, XPL Photo Courtesy: Jack Lewis Donnelly 14. Thin Section of a Sillimanite - a mineral found in rocks formed by the metamorphism of a mudstone. (XPL view) Photo Courtesy: Jack Lewis Donnelly 15. Microgeode in ultrabasic vulcanite (a rare copper telluride mineral), 30 µm thin section, PPL and XPL Photo Courtesy: Petr Hyks Photo Courtesy: Petr Hyks See original photo here 16. Muscovite & biotite (30 µm thin section, PPL and XPL) Photo Courtesy: Petr Hyks Photo Courtesy: Petr Hyks Same photo in XPL view. See original photo here 17. Quartz and epidote (30 µm thin section, PPL and XPL) Photo Courtesy: Petr Hyks Photo Courtesy: Petr Hyks See original here. 18. Olivine (30 µm thin section, PPL and XPL) Photo Courtesy: Petr Hyks See this photo here on Petr Hyks' website 19. Zircons in biotite (30 µm thin section, PPL views, showing extinction) Photo Courtesy: Petr Hyks See this photo here on Petr's website 20. Zircon in biotite (30 µm thin section, XPL) Photo Courtesy: Petr Hyks See this photo here on Petr's website 21. Kyanite surrounded by muscovite (30 µm thin section, PPL and XPL) Photo Courtesy: Petr Hyks See these photos on Petr's page here and here 22. Zircon crystal in chloritized biotite (30 µm thin section, PPL and XPL) Photo Courtesy: Petr Hyks See these photos on Petr's page here and here Petr Hyks is 21 year old geology student from Masaryk University in Brno (Czech Republic). He has uploaded 5000+ photos about geology, astronomy and meteorology on his Flickr page. Follow this link to visit his website. Thank you Petr for contributing to Learning Geology and helping others to learn geology through your thin section photos. 🙂 Now following 10 thin section photos are from a geology student of University of Helsinki, Finland. 23. Thin Section of Olivine Diabase in XPL and PPL view. Photo Courtesy: GeoAmethyst 24. Thin Section of Basalt in XPL view Having minerals: Olivine (in center) plagioclase, pyroxene and other accessory minerals Photo Courtesy: GeoAmethyst 25. Thin Section of a Trachyte, XPL view Trachyte is an igneous volcanic rock with aphanitic to porphyritic texture. It is volcanic equivalent of Syenite. Major or essential minerals are alkali feldspar with less amount of plagioclase, quartz or feldspathiod. Photo Courtesy: GeoAmethyst 26. Thin Section of a Harzburgite, XPL view Harzburgite is an ultramafic igneous rock. It chiefly contains plagioclase (under 10%) , olivine, orthopyroxene (enstatite), clinopyroxene (diopside) and biotite. There could be a small amount of talc, carbonate, tremolite, cummingtonite, chlorite, serpentine and titanite. Photo Courtesy: GeoAmethyst 27. Another thin section of Harzburgite, XPL view Photo Courtesy: GeoAmethyst 28. Thin Section of Pyroxenite (an ultramafic igneous rock), XPL view Photo Courtesy: GeoAmethyst 29. Thin Section of Trachyte showing Sandine mineral in center, XPL view Photo Courtesy: GeoAmethyst 30. Thin Section of Andesite, XPL view It is an extrusive igneous, of intermediate composition, with aphanitic to porphyritic texture. Here this thin section is showing chiefly hornblende and plagioclase. Photo Courtesy: GeoAmethyst 31. Thin Section of Alkali Basalt (silica undersaturated) in XPL view. Photo Courtesy: GeoAmethyst 32. Thin Section showing small clinopyroxene grains within orthopyroxene Photo Courtesy: GeoAmethyst Like this article? Leave a comment down or send us your valuable suggestion or feedback here to help us in improving this article. Useful Websites: 1. Polarized light Microscopy (Image Gallery) 2. How to make a thin section 3. Petrographic thin section preparation 4. Guide to Thin Section Microscopy 5. Index of Minerals in Thin Section 6. Optical Petrography website by an Italian Geologist 7. Carbonate Thin Section Images and Exercises
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