limestone is a sedimentary rocks,so it is not crystallization product of magma Prof Aiman
If calcite occurs in vugs and/or cracks, it's just a secondary mineral. You can find primary (magmatic) calcite only in carbonatites and/or kimberlites
Thank you for your valuable answer Prof. Nizar and Prof. Alessandro
https://www.researchgate.net/publication/229315468_Shallow_perched_groundwater_a_flux_of_deep_CO2_and_near-surface_waterrock_interaction_in_Northeastern_Jordan_An_example_of_positive_feedback_and_Darwin%27s_warm_little_pond
Article Shallow perched groundwater, a flux of deep CO2, and near-su...
I agree with A Cavallo. Think also about your primary minerals, depending on processes you will see calcite after calcic plagioclase.
if calcite fills cracks and cavities, it is a secondary product. . It can be asssociated to different diagenetic stages. The paragenetic sequence must be analyzed.
I think there is no way for calcite to be a primary mineral in this case. It could be only due to chemical precipitation once Ca and HCO3 have been dissolved from some of the primary minerals from the tuff. HCO3 is probably issued from CO2 degassing.
Dear Reyad, all of the contrbiutors answered your queation correctly, I need a summarization for all of the mechanism and time. Secondary calcites could be developed in tuffs several types or mechanism: (1) Diagenetic or post-diagenetic alterations (retrograde transformation) of primary (or magmatic) Ca-bearing minerals (e.g., calcic plagioclase, Ca-amphibole), (2) Diagenetic occurrences (authigenesis or neoformation) from diagenetic solutions as precipitated within the pores in the glassy matrix, (3) Post-diagenetic carbonate occurrences as filled pores or cracks which cut the primary volcanogenci and diagenetic materials. You need the careful textural observation on the optical microscopes. I hope these suggestions will be useful for you. Thank you for all contributors.
Yes we document what Omer describes in (2). Please see our publication: Antibus et al., 2014_Geochemistry, Geophysics, Geosystems 8.
Article Alteration of volcaniclastic deposits at Minna Bluff: Geoche...
may be a product of deposition in shallow marine environment. the material of volcanic eruption deposited to the shallow marine environment and it caused calcite is present in volcanic tuff.
It depends on the context the tuffs were deposited. So you may have either hydrothermal calcite or diagenetic one. See the other answers.
For over 20 years the USGS conducted extensive research of the tuffs that comprise Yucca Mountain (near Las Vegas, NV). The Topopah Spring tuff contains abundant secondary calcite. There are many papers describing the origin of the calcite, one of the best is by Paces et al., 2001, "Ages and Origins of Calcite and Opal in the Exploratory Studies Facility Tunnel, Yucca Mountain, Nevada" You can get the paper at:
http://pubs.er.usgs.gov/publication/wri20014049
(or I can send it to you directly)
You can also search the Research Gate contributions of Leonid A Neymark, Brian D. Marshall, or myself for additional Yucca Mountain papers on the topic.
Dear Dr. Al Dwairi,
Calcite can be precipitated during a wide range of processes. We studied volcaniclastic rocks along the Dead-Sea-Transform Fault and correlated the presence of zeolite and calcite with the hydrological regime being active there druing the recent past. Radiocarbon dating and isotope studies may be helpful tools. I would like to refer you to this paper which you can download from my RG profile.
DILL, H.G., TECHMER, A., BOTZ, R., DOHRMANN, R. and KAUFHOLD, S. (2012) Hypogene and supergene alteration of the zeolite-bearing pyroclastic deposits at Tell Rimah, Jordan, and rift-related processes along the Dead-Sea-Transform Fault System during the Quaternary.- Journal of Volcanology and Geothermal Research, 239-240: 49-68.
With my best regards
Harald G. Dill
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