scholarly journals Mineralogy of kimberley-type pyroclastic kimberlite and the transition to hypabyssal kimberlite

2019 ◽  
Keyword(s):  
Hypabyssal Kimberlite

The volatile content of hypabyssal kimberlite magmas: some constraints from experiments on natural rock compositions

2011 ◽  
Vol 73 (8) ◽  
pp. 959-981 ◽  
Author(s):  
Richard A. Brooker ◽  
R. Stephen J. Sparks ◽  
Janine L. Kavanagh ◽  
Matthew Field
Keyword(s):  
Volatile Content ◽  
Natural Rock ◽  
Hypabyssal Kimberlite

The Churchill kimberlite field, Nunavut, Canada: petrography, mineral chemistry, and geochronology

2008 ◽  
Vol 45 (9) ◽  
pp. 1039-1059 ◽  
Author(s):  
S. E. Zurevinski ◽  
L. M. Heaman ◽  
R. A. Creaser ◽  
P. Strand
Keyword(s):  
North America ◽  
Mantle Plume ◽  
Electron Microprobe ◽  
Mineral Chemistry ◽  
Eastern North America ◽  
Hudson Bay ◽  
Continental Extension ◽  
Group I ◽  
Hypabyssal Kimberlite ◽  
Kimberlite Field

Seventy-nine kimberlite intrusions have been identified in the Churchill Province, Nunavut, the result of an aggressive diamond exploration program by Shear Minerals Ltd. and their partners. This is one of Canada’s newest and largest kimberlite districts, situated immediately west of Hudson Bay between the communities of Rankin Inlet and Chesterfield Inlet. This study documents the occurrence of bonafide kimberlite rocks, classified as mainly sparsely macrocrystic, oxide-rich calcite evolved hypabyssal kimberlite and macrocrystic oxide-rich monticellite phlogopite hypabyssal kimberlite. Electron microprobe analyses of olivine, phlogopite, spinel, and perovskite support this petrographical classification. Low 87Sr/86Sr isotopic compositions determined from perovskite indicate a group I affinity. In addition, 27 precise U–Pb perovskite and Rb–Sr phlogopite emplacement ages have been determined for the Churchill kimberlites, indicating that magmatism spans ∼45 million years (225–170 Ma). The Churchill kimberlites belong to the NW–SE-trending corridor of Jurassic–Triassic kimberlite magmatism in eastern North America, which includes the Kirkland Lake, Timiskaming, and Attawapiskat kimberlite fields. Churchill kimberlites extend this corridor ∼800 km northwest, suggesting that the corridor may continue northwest with older kimberlites. This corridor is interpreted as the continental expression of magmatism linked to either a single or multiple mantle-plume hotspot track(s), a pattern geographically coincident with independent estimates for the timing and location of the continental extension of both the Great Meteor and Verde hotspot tracks.

Mineralogy of primary carbonate-bearing hypabyssal kimberlite, Lac de Gras, Slave Province, Northwest Territories, Canada

Lithos ◽  
2004 ◽  
Vol 76 (1-4) ◽  
pp. 415-433 ◽  
Author(s):  
John P. Armstrong ◽  
Mark Wilson ◽  
Robert L. Barnett ◽  
Tom Nowicki ◽  
Bruce A. Kjarsgaard
Keyword(s):  
Northwest Territories ◽  
Slave Province ◽  
Hypabyssal Kimberlite

Mineralogy of the P2-West ‘Kimberlite’, Wajrakarur kimberlite field, Andhra Pradesh, India: kimberlite or lamproite?

2013 ◽  
Vol 77 (8) ◽  
pp. 3175-3196 ◽  
Author(s):  
Gurmeet Kaur ◽  
R. H. Mitchell
Keyword(s):  
Andhra Pradesh ◽  
Evolutionary Trend ◽  
Evolutionary Trends ◽  
Similar Material ◽  
Alkaline Rocks ◽  
Fine Grained ◽  
Hypabyssal Kimberlite ◽  
Bona Fide ◽  
Kimberlite Field ◽  
Representative Material

AbstractA detailed mineralogical examination of representative material from the P2-West 'kimberlite' located in the Wajrakarur Kimberlite Field (India) demonstrates that significant differences exist between these rocks and archetypal hypabyssal kimberlite. The intrusion consists of an olivine-phyric facies which has been transected by, and includes clasts of, a consanguineous phlogopite-rich pegmatitic facies. The olivine-rich parts of P2-West are relatively fresh and consist of euhedral-to-subhedral microphenocrystal olivine set in a groundmass of fine-grained anhedral monticellite, amoeboid apatite, and subhedral-to-euhedral perovskite within a partially chloritized-to-fresh phlogopite-rich mesostasis. The rock lacks the abundant olivine macrocrysts characteristic of kimberlite. Monticellite crystals are commonly partially or completely replaced by pectolite and hydrogarnet. Similar material occurs as irregular aggregates randomly scattered throughout the groundmass. The groundmass, in contrast to that of hypabyssal kimberlites, is relatively poor in spinels. Atoll spinels are absent, with the majority of spinels occurring principally as mantles upon microphenocrystal olivine. Disaggregated cumulate-like assemblages of intergrown anhedral perovskite and spinel are common. Spinel compositions are unlike those of kimberlites and their evolutionary trend is similar to that of lamproite and lamprophyre spinels. The pegmatitic facies of the intrusion are highly and pervasively altered, and characterized by the presence of large clasts, veins, and irregular aggregates consisting of large (1–5 mm) crystals of pinkish-bronze Al-poor phlogopite intergrown with and/or including: apatite; pectolite-hydrogarnet pseudomorphs after an unidentified euhedral phase; chlorite laths; barytolamprophyllite; perovskite; tausonite; diverse Sr-Ba-carbonates; and baryte. The presence of barytolamprophyllite and tausonite are typical of potassic undersaturated alkaline rocks and have never been reported from kimberlite; however, neither feldspar nor feldspathoids are present in P2-West. Micas in fresh and altered rocks are Al2O3- and BaO-poor, and exhibit compositional evolutionary trends towards tetraferriphlogopite rather than kinoshitalite. On the basis of these mineralogical data it is suggested that P2-West represents an unusual lamproite-like intrusion which has undergone extensive hydrothermal deuteric alteration and should not be considered a bona fide kimberlite.

Petrology of the hypabyssal kimberlite of the Kroonstad group II kimberlite (orangeite) cluster, South Africa: Evolution of the magma within the cluster

Lithos ◽  
2011 ◽  
Vol 125 (1-2) ◽  
pp. 795-808 ◽  
Author(s):  
Geoffrey H. Howarth ◽  
E. Michael ◽  
W. Skinner ◽  
Stephen A. Prevec
Keyword(s):  
South Africa ◽  
Hypabyssal Kimberlite ◽  
Group Ii
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