 | | Journal (article/letter/editorial) | | Early Paleoproterozoic Monchegorsk Layered
MaficāUltramafic Complex, Kola Peninsula
E. V. Sharkov and A....comprises two independent large layered
maficāultramafic intrusions: the Monchegorsk pluton and the Main...Early Paleoproterozoic Monchegorsk layered
maficāultramafic complex situated in the northeast
ern Baltic...km2. These are the Monchegorsk
Nibearing maficāultramafic pluton (Monchepluton)
and the Main Range mafic...Early Paleoproterozoic (2.5ā2.4 Ga) layered
maficāultramafic intrusions with NiāCuāPGE min
eralization localized |  | | Journal (article/letter/editorial) | | units containing high proportions of adcumulate dunite.
Cumulate flow units have been mapped in detail...within
the dunite lenses. In the stratigraphically equivalent Kathleen East area adcumulate dunite grades...where the
Perseverance ultramafic complex consists of a thick central dunite lens flanked on one side by...indicate an extrusive origin for the adcumulate dunite bodies.
The Waiter Williams Formation, in the west-central...consists of a central sheet-like body of
adcumulate dunite, underlain and overlain by olivine orthocumulates |  | | Journal (article/letter/editorial) | | intrusions of different age: the Monchegorsk pluton of ultramafic and
mafic rocks and the predominantly gabbroid...features and probably be parts
of a single large intrusion (the Monchegorsk intru
sion), in which the Monchegorsk...1978; Mitrofanov,
1995; Daly et al., 2006). From north to south, these
blocks are (1) the Murmansk block...its probable analogues: (a) mafic
rocks, (b) ultramafic rocks; (2) Paleoproterozoic volcanoāsedimentary...(4) units of rhyth
mic alternating mafic and ultramafic cumulates, including
dunites; (5) predominantly |  | | Report (article/chapter) | | Systematic PGE analysis of all the mafic
and ultramafic igneous and alteration lithologies in the ophiolite...anomalous PGE occurrences throughout the cumulate ultramafic sequence and their
distribution is described...chromite-rich
sulphide-bearing dunite forming a small part of a 200 m dunite lens in mantle harzburgite
close...dunites also within this dunite lens. The only other chromiterich dunite lens in the Cliff area also has...values are restricted to magmatic
chromite-rich dunite lenses. PGE analyses of drill core from beneath |  | Duuring, Paul, Bleeker, Wouter, Beresford, Steve W., Hayward, Nicholas (2010) Towards a volcanicāstructural balance: relative importance of volcanism, folding, and remobilisation of nickel sulphides at the Perseverance NiāCuā(PGE) deposit, Western Australia. Mineralium Deposita, 45 (3) 281-311 doi:10.1007/s00126-009-0274-y | Journal (article/letter/editorial) | | along the western margin of the
Perseverance Ultramafic Complex (PUC). The PUC comprises
a basal nickel...overlain by a thicker,
nickel sulphide-poor, dunite lens. Hanging wall rocks include
rhyodacite that is...partitioning of strain along the margins of the competent
dunite. A mylonite developed in the more ductile footwall...stress domains along the fringes of the
elongated dunite lens. Strata-bound massive and disseminated
nickel...rocks to the thick, olivine adcumulate-textured dunite
lens (Barnes et al. 1988a; Fig. 2). These researchers |  | Yang, Sheng-Hong, Hanski, Eero, Li, Chao, Maier, Wolfgang D., Huhma, Hannu, Mokrushin, Artem V., Latypov, Rais, Lahaye, Yann, OāBrien, Hugh, Qu, Wen-Jun (2016) Mantle source of the 2.44ā2.50-Ga mantle plume-related magmatism in the Fennoscandian Shield: evidence from Os, Nd, and Sr isotope compositions of the Monchepluton and Kemi intrusions. Mineralium Deposita, 51 (8) 1055-1073 doi:10.1007/s00126-016-0673-9 | Journal (article/letter/editorial) | | from the upper chromitite layers of the Kemi intrusion and
most samples from the previously studied Koitelainen...sources.
The widespread ca. 2.44 to 2.50-Ga mafic-ultramafic
magmatism in the Fennoscandian Shield is thought...background and petrography
Kemi
The Kemi layered intrusion is located near the town of Kemi
in northwestern...of the intrusions of the
Tornio-NƤrƤnkƤvaara intrusion belt running from the western
to eastern border...of
ca. 2.44 Ga for the intrusion (Perttunen and Vaasjoki 2001).
The intrusion strikes northeastward and |  | Derbyshire, E.J., O'Driscoll, B., Lenaz, D., Zanetti, A., Gertisser, R. (2019) Chromitite petrogenesis in the mantle section of the Ballantrae Ophiolite Complex (Scotland) Lithos, 344. 51-67 doi:10.1016/j.lithos.2019.06.013 | Journal (article/letter/editorial) | | harzburgite typically hosts veins and sheets of
ED
dunite, pyroxenite and chromitite (>60 vol.% Cr-spinel)...populations of
chromitites in the Kempirsai ophiolite (Kazakhstan), one with high Cr# [Cr/(Cr+Al)] Cr-spinel and...Valley Fault and unconformably overlain to the north
by younger Llanvirn Barr and Caradoc-Ashgill Ardmillian...invoking folding of the lava sequence, serpentinite intrusion and an anticlinal structure for the
PT
complex...comprises variably serpentinised harzburgite and dunite
which crop out in two broad NE-SW trending belts |  | FarkaÅ”, Juraj, ChrastnĆ½, Vladislav, NovĆ”k, Martin, Äadkova, Eva, PaÅ”ava, Jan, Chakrabarti, Ramananda, Jacobsen, Stein B., Ackerman, LukĆ”Å”, Bullen, Thomas D. (2013) Chromium isotope variations (Ī“53/52Cr) in mantle-derived sources and their weathering products: Implications for environmental studies and the evolution of Ī“53/52Cr in the Earthās mantle over geologic time. Geochimica et Cosmochimica Acta, 123. 74-92 doi:10.1016/j.gca.2013.08.016 | Journal (article/letter/editorial) | | such as peridotites (lherzolite, harzburgites, dunite), pyroxenites and their alteration/metamorphic...0.082 Ā± 0.058& (2SD), (samples from
Bushweld Intrusion, South Africa; and Great Dyke, Zimbabwe, cf. Schoenberg...the Alpine orogen
(podiform chromite in residual dunite and
harzburgites)2
Bosnia
Mid-oceanic ridge settings...peridotite/serpentine)1214
Macedonia MORB (?) chromite in dunite rocks3,14
M-Neoproter.
(1758ā584 Ma)
PrFUK 20...settings of the Uralian orogen (chromite in dunite lens in Ordovician (470
PAS 1
Ural,
Centralnoje
harzburgites)4 |  | | Report (issue) | | Ultrabasic Group .
Field Relations
Petrography of Dunite
Mineralogy of Chromite Deposits
Mineralogy of Late...
Geological Map of the Hangha Chromite Mining
District, reduced from 1 : 2,500 Field Survey
"
Surface...Chromiferous Dunite
Lens
" 14
Subsurface Geology of the Amba Chromiferous
Dunite Lens .
,, 15
Cross-section...Cross-section of the Amba Lens at Co-ordinate
Line 225 North
,, 17
Surface Geology of the North and South Bendu...I. Banded Chromiferous Dunite from Amba Pit, Hangha Chromite Mining
District, Sierra Leone.
2. Detail |  | | Journal (article/letter/editorial) | | grains in olivine orthocumulate, Mt Keith
Western Ultramafic Complex, back-scattered electron image; (b) skeletal...chromite enclosing small olivine grains, Six
Mile dunite body, reflected light; (d) lobate chromite, showing...partially serpentinized olivine grains, Mt Clifford dunite body; (e) āchicken-wireā textureāchains of euhedral...the
Airport Ultramafic Complex at Wiluna (Hunter et al.,
1994), and large sheeted dunite bodies in the...mainly of chromites in ophiolitic or āalpine
ultramaficā complexes (Onyeagocha, 1974; Ulmer, 1974;
Evans |  | | Journal (article/letter/editorial) | | et al.,
1990).
The Pindos ocean extends further north in Albania
and Yugoslavia. Ophiolites in Yugoslavia...ophiolite belt consisting mainly
of harzburgite-dunite exhibits economically significant chromite potential...363-381
all chromite ores are found within dunite bodies or
dunite envelopes in harzburgite, there is not...not a systematic relation between size of the dunite body and
that of the ore body. The sizes of the ore...deposits of W. Chalkidiki peninsula
occur in altered dunite and mostly are of schlieren
type, though occurrences |  | | Book | | phrases as <Kazakhstan,Ā» etc., appeared in the Russian papers.
In non-Russian...territory of the former Soviet Union, the Urals, Kazakhstan,
and Central Asia, where many new minerals were...of
Ct,ervonograd, Lvov-Volyn coal basin, Lvov district, W Ukraine. This
mineral fills small cavities...tungsten deposit, Betpakdala Desert, Central Kazakhstan (earlier
the Solnechnoye was known as the Western...brown iron ore deposit north of the
n of Maļæ½nitka,
1aļæ½lied Ā«ps1lome Zlatoust district, S Urals. This specimen |  | Lesher, C. M., Burnham, O. M., Keays, R. R., Barnes, S. J., Hulbert, L. (2001) TRACE-ELEMENT GEOCHEMISTRY AND PETROGENESIS OF BARREN AND ORE-ASSOCIATED KOMATIITES. The Canadian Mineralogist, 39 (2) 673-696 doi:10.2113/gscanmin.39.2.673 | Journal (article/letter/editorial) | | Perseverance, Western Australia
The Perseverance Ultramafic Complex (PUC) occurs in the northern part of...0.5-km-thick lens of adcumulate
metadunite and mesocumulate metaperidotite (Dunite
Lens: DL) that is...ocean
island basalt (Sun & McDonough 1989); NASC, North American Shale Composite (Gromet et al. 1984). ...et al. 1999, in press). The
DL is flanked to the north and south by barren
orthocumulate and spinifex-textured...and PUS units). The Rockyās Reward ultramafic
unit (RR) to the north is interpreted as an attenuated
tectonic |  | | Journal (article/letter/editorial) | | by the Perseverance Ultramafic Complex, which consists of a central dunite lens, 700 m thick by 3 km...of spinifex-textured flows flanking the central dunite show well constrained, linear
trends of major and...unmineralised flows at the base of the Perseverance Ultramafic Complex all show evidence for LREE enrichment...by the spinifex textured units
flanking the dunite lens. Compositions of komatiite liquids, sulphides...deposit and the immediately overlying Perseverance Ultramafic Complex, have been the subject
of extensive study |  | Rosengren, N. M., Grguric, B. A., Beresford, S. W., Fiorentini, M. L., Cas, R. A. F. (2007) Internal stratigraphic architecture of the komatiitic dunite-hosted MKD5 disseminated nickel sulfide deposit, Mount Keith Domain, Agnew-Wiluna Greenstone Belt, Western Australia. Mineralium Deposita, 42 (8) 821-845 doi:10.1007/s00126-007-0139-1 | Journal (article/letter/editorial) | | Internal stratigraphic architecture of the komatiitic
dunite-hosted MKD5 disseminated nickel sulfide
deposit...deposit is hosted by the Mount
Keith Ultramafic Complex (MKUC), a dunite body of
komatiitic affinity located...internal units that range
from extreme adcumulate dunite to relatively fractionated
pyroxenitic and gabbroic...is interpreted
to represent a later pulse of ultramafic magma, emplaced
stratigraphically above the main...despite apparent geometrical differences between lens and
sheet komatiitic dunites, a broad facies architecture |  | Derbyshire, E.J., O'Driscoll, B., Lenaz, D., Gertisser, R., Kronz, A. (2013) Compositionally heterogeneous podiform chromitite in the Shetland Ophiolite Complex (Scotland): Implications for chromitite petrogenesis and late-stage alteration in the upper mantle portion of a supra-subduction zone ophiolite. Lithos, 162. 279-300 doi:10.1016/j.lithos.2012.11.013 | Journal (article/letter/editorial) | | podiform chromitite bodies enclosed in elongate dunite lenses in the vicinity of
the petrological Moho...occurrence of chromitite seams in the centres of the dunite lenses combined with variable
Cr-spinel compositions...antigorite). Magmatic
sulphide (e.g., pentlandite) in dunite and chromitite is locally converted to reduced...Moho demarcates the transition from harzburgite to dunite at the base of the
Moho transition zone (O'Driscoll...Prichard and Lord,
1993), typically encased in dunite lenses and concentrated directly
above and below |  | | Journal (article/letter/editorial) | | spatially associated with a lenticular body of ultramafic rocks which
shows a concentric zonation in metamorphic...enstatite
assemblages occur at the margin of the ultramafic lens,
giving way to olivine + anthophyllite, olivine...pre-metamorphic marginal alteration of the ultramafic lens. Metamorphic fluids were essentially binary...Metamorphic mineral assemblages in the lenticular ultramafic body at the Agnew mine show an overall zonation...is stable in the Agnew area, and in rocks as far north as
the Six Mile deposit. Binns and Groves (1976) |  | | Journal (article/letter/editorial) | | compound peridotite facies, and dunite lens
subfacies in compound dunite facies (Barnes, 2006a). The strong...al., 2004; Rosengren
et al., 2005). Komatiitic dunite-associated deposits dominantly occur
in the northern...peridotiteassociated deposits are type 1 deposits. Komatiitic dunite-associated
deposits appear to be both type 1 (e...identiļ¬cation (section 3, Appendix A) is the komatiitic
dunite/komatiitic peridotite distinction.
3. Methods...Singer et al., 2001). Deposits in all komatiitic dunite
control areas in the Kalgoorlie Terrane, except |  | | Journal (article/letter/editorial) | | habits. In the Six Mile Well ultramafic complex
in the Yakabindie region of the Agnew-Wiluna greenstone...ultramafischen Komplex Six Mile Well in der Yakabindie-Region des Agnew-WilunaGriinsteingtirtels und in anderen...Greenstone
Belt, showing the location of the Yakabindie region
and the Six Mile Well deposit
Poikilitic chromite...through the Six Mile Well ultramafic complex, after Hill et al. (1990)
north western part of the Eastern...by extensive
komatiite lava rivers. The Six Mile dunite body (Figs. 1, 2), previously described by
Naldrett |  | | Report (issue) | | on a suite of rock samples from
the Josephine ultramafic complex in northern California in an attempt...measurements of samples indicate that chromite,
dunite and harzburgite can be mutally separated by using...exclusively in dunite lenses
in a country rock made up almost entirely of harzburgite.
The dunite and
harzburgite...remaining interstitial material is derived from
dunite, and is largely serpentine minerals.
The chromite...increased amount of
tectonization in its enveloping dunite lens.
The consequence, therefore, of
the tectonic |  | | Journal (article/letter/editorial) | | Fe-rich tholeiiticbasalts, gabbros, komatiitic ** ultramafic
rocks and some basalts which appear chemically...sulfide mineralization occurs mainly within the dunite pods as large (in excess of 70"106
tonnes) low...magnesian liquid, it is postulated that the source region of the mantle
must have been melted twice, once...vicinity of
Kalgoorlie in the Eastern Goldfields region of Western Australia have been
well documented...mineralization is associated with sequences
of ultramafic flows (komatiites*), c o m m o n l y occurring |  | | Journal (article/letter/editorial) | | upper mantle depleted harzburgite and cumulative dunite from crustal sections of the
Neyriz ophiolite,...ophiolite complex is mainly composed of tectonized
ultramafic rocks. The mantle section is composed of a
nearly...It becomes highly depleted and interlayered
with dunite upward into the mantleācrust transition zone
(Fig...section, comprising a thick massive serpentinized dunite, occurs immediately on the mantleācrust
transition...(including depleted harzburgite and
subordinate dunite) and grades progressively into
wehrlite (Fig. 2c) |  | | Report (issue) | | metallurgy would be inevitable (Thayer, 1973).
Ultramafic rocks of the alpine peridotite type are common...northwestern California because of the presence in this
region of a few unmined or partially mined podiform chromite...studies, the
physical properties of a suite of ultramafic rocks and chromites
were determined in the laboratory...Photograph showing cumulate textures in chromitiferous dunite._ 11
3. Rose diagram of steep faults cutting the...layers in harzburgite ____________________ 17
6. Dunite with discontinuous zone of orthopyroxenite in
harzburgite |  | | Journal (article/letter/editorial) | | ation
ore depositsnear the base of the cumulate
dunite during episodiccrystallizationat localizedcenterswithin...accompanying.
penetrativedeformationof the lower ultramafic rocks
causedthe tectonicoverprint of schlierenstructureson...trondhjem-
passesdown into plutonicmafic and ultramafic rocks ires, throughpyroxenitesand feldspathicperidotites...trending axis, and erosion,have exposedthe Within ultramafic portions of the ophiolite series,
rocksin a seriesof...Other
lithologic
boundary
I!ā¢'ā¢ DUNITE
with
subordinate
CLINOPYROXENE-DUNITE
Compositional
layering/foliation |  | | Report (issue) | | ___ ___ 4
3-5. Photographs of:
3. Chromitiferous dunite showing ehromite-net and occluded-silicate textures...______________________________ 7
5. Orthopyroxenite layers and dunite layers in harzburgite __________________________________...Photographs of:
7. Chromite foliation in dunite at high angle to dunite-harzburgite contact _________________________...texture in dunite __________________________________________ 11
9. Flattened rods of ehromite in dunite at an...an angle to dunite-harzburgite contact _____________________ 11
10-12. Sketches illustrating:
10. Isoclinal |
|