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varvite


varvite
Photo Information
Copyright: Paulo Henrique Maziero (maziero) Gold Star Critiquer/Gold Note Writer [C: 224 W: 0 N: 192] (1503)
Genre: Places
Medium: Color
Date Taken: 2009-06-27
Categories: Nature
Camera: Canon EOS Rebel XTi, Canon 18 - 55mm EFS
Exposure: f/5.6, 1/100 seconds
Details: (Fill) Flash: Yes
Photo Version: Original Version
Theme(s): Rocks [view contributor(s)]
Date Submitted: 2009-07-03 11:19
Viewed: 244
Points: 32
[Note Guidelines] Photographer's Note
Varvite is the name used by the geologists to designate a special kind of sedimentary rock formed by the repetitive succession of plates or layers, each one of them deposited during the period of one year.

Each plate or layer of varvite is, actually, a pair formed of an inferior portion, thicker (from centimeters to decimeters), of sandstone or siltstone, with a lighter color, followed by a thinner portion (milimeters) of siltstone or mudstone, with a darker color (dark gray).

The name derives from the word varve, of Swedish origin, generally used to designate sedimentary seasonal deposits, that is, controled by the variation of the seasons of the year. The most common type of varve is represented by plates, or layers, of sediments deposited in lakes formed in front of the glaciers, through the water dams produced by the ice melting, during the phase of moving back of the glaciers.

The rhythmites from the Brazilian Permian have shown a characteristic ichnofauna related to glacial environments. These rhythmites, considered as varvites, occur in two sedimentary basins located in Central (Sanfranciscana Basin) and Southern (Paraná Basin) Brazil. The classical exposure is the varvite of Itararé Group (Paraná Basin, Permian) nearby the city of Itu (central-eastern of São Paulo State).

Sedimentological, palynological and paleomagnetic evidenceindicate probable seasonal (annual) control on the deposition ofthe lithologic pairs of the varvite, as in Pleistocene varve clays.About 300 pairs are present in the Itu quarry.

Typical sedimentary structures of the varvite arebeautifully exposed in the quarry, as well as abundant ichnofossilsassigned to aquatic, benthonic invertebrates. Though relativelyrare, dropstones of varied composition and size (up to 2 metersin diameter) and mounds of glaciogenic debris liberated fromicebergs are found dispersed in the rock.

Probable depositional environment of the varvite was aproglacial water body or lake partially or temporarily in contactwith the glacier margin. The light, sandstone/siltstone beds/laminae were deposited by dense flows /turbidity currents duringsummer, followed by the settling of muds from suspension duringwinter, when the lake was frozen over.

The Itu quarry, the best exposure of glacial rhythmiteknown in the Paraná Basin, represents a classic geologicalmonument related to late Paleozoic glaciation. The monument iswell preserved within the Parque do Varvito (Varvite Park).

This is one of some images that I obtained during the expedition whom we made during one day entire for a geologic route where we could better study and understand the processes of rocky formation of the terrestrial crust.

To know more:

http://pt.wikipedia.org/wiki/Varvito

http://www.itu.com.br/hotsite/default.asp?id=65
tanburi, sudipparbat, Niva, burak28, brunorsantana, ele_eng, Silvio2006, harpya, ricardomattos, mbrito, mvdisco, Fortuna, cunejo200, zomik, isa, bucanas has marked this note useful
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Critiques [Translate]

Hello Paulo,
wonder of nature like a book.
Clear image good angle of wiew

TFS
Selahattin E

Ola Paulo.
Something complete behind the obvious.!
Well seen and captured.
Hope you dont mind not reading the long story in total, haha
Best wishes from Jan

  • Great 
  • Niva Gold Star Critiquer/Gold Note Writer [C: 1146 W: 2 N: 838] (10379)
  • [2009-07-03 12:41]

Olá Paulo
Um texto muito interessante e explicativo ajudado pela ótima qualidade da fotografia, mostrando em detalhes as camadas e texturas deste tipo de rocha.
Parabéns pela apresentação!
Um abraço, até a próxima!
Nivaldo

Que grande sacada, Paulo! Ótimo ângulo escolhido e linda textura desse interessante tipo de rocha. Belos detalhes e a combinação das áreas com e sem foco ficou muito legal. Meus parabéns, amigo!

Grande abraço e ótimo fim de semana!
Bruno

Hi Paulo
This is another aspect of nature harmony
Great point of view with nice exposure
The details are amazing, well done my friend
Best wishes
Alireza

Ciao Paulo, wonderful composition with interesting geological formation, fantastic texture, very well done, have a good week end, ciao Silvio

Ciao Paulo



Um excelente texto explicativo,
eu não conhecia a beleza destas pedras,
e aqui temos um belo e grosso livro de
pedra com finos detalhes em tuas linhas.
interessante visual e bom macro na pedra.
Saudações e bom WE 4 you.

Sergio

Hello Paulo!
Beautiful image,with great angle of view!
formation of nature harmony,with interesting details and texture!
Regards and tfs
Kostas

Olá Paulo,
Belo trabalho, mostrando a geometria,textura e cores desta formação rochosa.Parece que foram assentadas mesmo pelas mãos do Criador.Excelente nota também.
Abraço
Ricardo

  • Great 
  • mbrito Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 1621 W: 118 N: 2791] (11262)
  • [2009-07-04 12:09]

Hi Paulo,
Excellent sharpness in this texture photo; great light and detail, and a strong presentation in angle adding a great dinamis to the image.
Best regards, mb

Hi Paulo Henrique,
A nice presentation and composition,
Excellent POV. and details
great colors and sharpness,
Excellent note of the sujet.
very well taken and done.
My compliments
Michel

Boa noite Paulo,

Excelente close nessa bela formação rochosa!
Foto bem nítida e com um agradável colorido.
Parabéns e um grande abraço,
Sergio

Ciao Paulo,
A fine perspective and texture of the isolated scene. At first I thought it was timber or wood but was amazed to find that it is a mineral. I wonder whether a higher f stop would further enhance texture and sharpness. Well done, it is an absorbing posting. Best regards....Danilo

  • Great 
  • zomik Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 212 W: 64 N: 228] (2889)
  • [2009-07-05 7:09]

Hello Paulo,
very interesting display and the description.
Good composition and very well shrapness.
best regards, greetings from Poland :)
Zofia

  • Great 
  • isa Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 353 W: 50 N: 687] (4071)
  • [2009-07-06 10:46]

Olá Paulo,
Interessante composição onde fica o registo paleontológico dos sedimentos muito antigos, contando a história da Terra. Excelente enquadramento e aproveitamento do ângulo. O registo permite visualizar perfeitamente muitos pormenores. Bela moldura.
Parabéns pelo registo e pela divulgação.

Um abraço.
Isa

Que bela foto! Estas rochas sedimentares são uma verdadeira régua do tempo. Impressiono-me muito com isso...
Foto com um belo enquadramento e uma textura incomum, rústica.
Um belo olhar! Meus parabéns, Paulo!
Abraço,
Shyguek

Ola Paulo,
Otima composicao,boa perspectiva e bom trabalho.
Abracos,
Ralf

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