Diamond From the Guaniamo Area, Venezuela

Kaminsky, Felix V.; Zakharchenko, Olga D.; Griffin, William L.; Channer, Dominic M. DeR.; Khachatryan-Blinova, Galina K.

doi:10.2113/gscanmin.38.6.1347

Cited by 77 publications

(66 citation statements)

References 27 publications

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“…However, the distribution of diamond numbers and size at Los Coquitos is approximately log-normal, meaning that the diamond parcel is representative of this alluvial deposit. The proportions of +2 mm and -2+1 mm diamond crystals are almost equal in number in this placer, whereas in the Quebrada Grande deposits, diamond crystals of size classes -2+1 mm dominate in both weight and number (Kaminsky et al 2000).…”

Section: Sample Information and Analytical Methodsmentioning

confidence: 66%

“…Errors on the concentrations determined were less than 20%. One can fi nd the principles that were used for interpretation of IR analysis of diamond in Kaminsky et al (2000Kaminsky et al ( , 2001b, Kaminsky & Khachatryan (2001, and Khachatryan & Kaminsky (2003). Isotope analyses were performed by K. Maltsev (GEOHI, Russia) using samples from 2 to 15 mg in weight with the VARIAN-MAT-230 mass spectrometer; this was done with an accuracy of <0.1‰ PDB ( 13 C/ 12 C PDB = 0.0112372).…”

Section: Sample Information and Analytical Methodsmentioning

confidence: 99%

“…Trace-element analyses of selected inclusions of mineral phases were carried out by laser-ablation microprobe ICP-MS, using techniques similar to those described by Kaminsky et al (2000Kaminsky et al ( , 2001a.…”

Section: Sample Information and Analytical Methodsmentioning

confidence: 99%

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Diamond From the Los Coquitos Area, Bolivar State, Venezuela

Kaminsky

Zakharchenko

Khachatryan

et al. 2006

The Canadian Mineralogist

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C, of the Los Coquitos diamond vary from +0.4 to -20.5‰, compared with -3.2 to -28.7‰ in the Quebrada Grande diamond. In the Los Coquitos suite, mineral inclusions in diamond are characterized by a lower Ca content in garnet, wider compositional variations in pyroxene (mg in the range 0.683-0.849), and lower Fo component in olivine (mg in the range 0.926-0.932), compared to inclusions in diamond in the Quebrada Grande suite. Los Coquitos diamond shows greater depletion in LREE compared to Quebrada Grande diamond. Diamond crystals at Los Coquitos were derived, at least in part, from a new, undiscovered kimberlite source in the Guaniamo River basin. These rocks are similar in type to the Quebrada Grande kimberlites, but were sampled from a different section of the subcontinental lithospheric mantle. The existence of two separate populations of diamond, each with its own primary source, suggests that other localities of placer diamond in Venezuela may have their own local sources.

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Section: Sample Information and Analytical Methodsmentioning

confidence: 66%

Section: Sample Information and Analytical Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Diamond From the Los Coquitos Area, Bolivar State, Venezuela

Kaminsky

Zakharchenko

Khachatryan

et al. 2006

The Canadian Mineralogist

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“…One of the evidences of possible variations of the composition of fluid in kimberlite diamonds may be the wide range of K contents in pyroxenes entrapped during diamond growth (8,13,(76)(77)(78). Other direct evidences of significant variations of fluid composition during diamond crystal growth are presented in refs.…”

Section: Discussionmentioning

confidence: 96%

The role of mantle ultrapotassic fluids in diamond formation

Palyanov

Shatsky

Sobolev

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Analysis of data on micro-and nano-inclusions in mantle-derived and metamorphic diamonds shows that, to a first approximation, diamond-forming medium can be considered as a specific ultrapotassic, carbonate/chloride/silicate/water fluid. In the present work, the processes and mechanisms of diamond crystallization were experimentally studied at 7.5 GPa, within the temperature range of 1,400 -1,800°C, with different compositions of melts and fluids in the KCl/K 2CO3/H2O/C system. It has been established that, at constant pressure, temperature, and run duration, the mechanisms of diamond nucleation, degree of graphite-to-diamond transformation, and formation of metastable graphite are governed chiefly by the composition of the fluids and melts. The experimental data suggest that the evolution of the composition of deep-seated ultrapotassic fluids/melts is a crucial factor of diamond formation in mantle and ultrahigh-pressure metamorphic processes. high-pressure experimentA n important stage in solving problems of diamond genesis is constructing a clear physical model of diamond formation (1). One of the key parameters to be modeled is the composition of the diamond crystallization medium, with a fluid being largely considered as a crucial agent in diamond formation. It is generally agreed that the mantle media of diamond crystallization were volatile-saturated melts or fluids (1-7). Carbonbearing fluids and carbonates could be sources of carbon, and the medium could have been saturated with it by redox reactions. Recent studies have been aimed at searching and examining fluid and fluid-containing inclusions in genetically different diamonds. Also, experiments have been performed to model the processes of diamond crystallization in the media compositionally corresponding to the inclusions. It is the combination of these two approaches that permits us to gain deeper insight into diamond genesis and to better understand the specific character of processes of deep-seated mineral formation.Studies of mineral inclusions in diamonds have determined the main types of diamondiferous parageneses: ultramaffic, eclogitic (4,8,9), and intermediate websterite (10) and calc-silicate types (11). Some mineral inclusions, e.g., intergrowths of phlogopite with pyroxene (8, 12, 13) and phlogopite with calcite (14), are unambiguously evidence that K and H 2 O were present in the diamond-forming medium. It is pertinent to note that, as early as 30 years ago, neutron activation analysis of diamonds without visible inclusions, taken from three South African deposits, revealed a mixture of mostly K and of other components, which was interpreted as evidence of the presence of entrapped melt (15). Principally, more recent information has accrued from micro-and nano-inclusions in mantle-derived and metamorphic diamonds. Analysis of the composition of the inclusions in fibrous or cloudy mantle diamonds shows that, at the time of entrapment, the inclusion matter was a specific fluid whose composition belongs to one of the three main types: (i) ...

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“…MgO content in all these grains is very low (<0.81 wt%). Inclusions of lowMg, Mn-ilmenite were found in placer diamonds from Guaniamo, Venezuela [24][25][26] . Also, the manganilmenites found in tills across Lena West both in and outside the Cretaceous basin are similar to those in the kimberlites from Guanaimo 27 .…”

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confidence: 98%