Key processes determining secondary alterations in kimberlites
| Autor: | L.G. Kuznetsova, V. B. Vasilenko, V. A. Minin, A. V. Tolstov |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Recrystallization (geology)
020209 energy Rare earth Geochemistry Diamond 02 engineering and technology engineering.material 010502 geochemistry & geophysics 01 natural sciences chemistry.chemical_compound Geophysics chemistry Geochemistry and Petrology Vadose zone Carbon dioxide 0202 electrical engineering electronic engineering information engineering engineering Kimberlite Chemical composition Diamond crystal Geology 0105 earth and related environmental sciences |
| Zdroj: | Geochemistry International. 54:369-377 |
| ISSN: | 1556-1968 0016-7029 |
| DOI: | 10.1134/s0016702916020075 |
| Popis: | A variety of hypotheses have been put forward as to the nature of secondary alteration. They were tested by using the amount of insoluble SiO2 accumulated in the rocks (Q) as the index of secondary alteration degree. This parameter allows any sample to be characterized with the degree of its secondary alteration. By putting Q values together with contents of CaO and rare earth elements, features of diamond crystal size distributions within samples in most altered kimberlites, and the distribution of these parameters over kimberlite bodies, we show that secondary processes occurred when kimberlites were exposed to postmagmatic solutions: fluids containing water and carbon dioxide. Endogenous fluids rose from the bottom of pipes along narrow local zones and spread beyond them at the top, involving larger rock masses. There, they mingled with vadose and phreatic water. The basicity decreased abruptly, inducing profound changes of rock-forming minerals and alteration of diamond crystal weight distribution by recrystallization. The study invokes a great body of factual information, including hundreds and thousands of analyzes of kimberlites from Yakutian diamond pipes: Botuobinskaya, Nyur’inskaya, Maiskaya, Internatsional’naya, Mir, Aikhal, Yubileinaya, Sytykanskaya, Udachnaya-West, and Udachnaya-East. |
| Databáze: | OpenAIRE |
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