The lithospheric mantle beneath the Kerguelen Islands (Indian Ocean): petrological and petrophysical characteristics of mantle mafic rock types and correlation with seismic profiles

2001 ◽  
Vol 142 (2) ◽  
pp. 244-259 ◽  
Author(s):  
M. Grégoire ◽  
I. Jackson ◽  
S. O'Reilly ◽  
J. Cottin
Keyword(s):  
Indian Ocean ◽  
Lithospheric Mantle ◽  
Mafic Rock ◽  
Seismic Profiles ◽  
Kerguelen Islands ◽  
Rock Types

scholarly journals Igneous Rock Associations 26. Lamproites, Exotic Potassic Alkaline Rocks: A Review of their Nomenclature, Characterization and Origins

2020 ◽  
Vol 47 (3) ◽  
pp. 119-142
Author(s):  
Roger H. Mitchell
Keyword(s):  
Partial Melting ◽  
Lithospheric Mantle ◽  
Tectonic Setting ◽  
Alkaline Rock ◽  
Mantle Metasomatism ◽  
Geochemical Evolution ◽  
Alkaline Rocks ◽  
Isotopic Compositions ◽  
Economic Significance ◽  
Rock Types

Lamproite is a rare ultrapotassic alkaline rock of petrological importance as it is considered to be derived from metasomatized lithospheric mantle, and of economic significance, being the host of major diamond deposits. A review of the nomenclature of lamproite results in the recommendation that members of the lamproite petrological clan be named using mineralogical-genetic classifications to distinguish them from other genetically unrelated potassic alkaline rocks, kimberlite, and diverse lamprophyres. The names “Group 2 kimberlite” and “orangeite” must be abandoned as these rock types are varieties of bona fide lamproite restricted to the Kaapvaal Craton. Lamproites exhibit extreme diversity in their mineralogy which ranges from olivine phlogopite lamproite, through phlogopite leucite lamproite and potassic titanian richterite-diopside lamproite, to leucite sanidine lamproite. Diamondiferous olivine lamproites are hybrid rocks extensively contaminated by mantle-derived xenocrystic olivine. Currently, lamproites are divided into cratonic (e.g. Leucite Hills, USA; Baifen, China) and orogenic (Mediterranean) varieties (e.g. Murcia-Almeria, Spain; Afyon, Turkey; Xungba, Tibet). Each cratonic and orogenic lamproite province differs significantly in tectonic setting and Sr–Nd–Pb–Hf isotopic compositions. Isotopic compositions indicate derivation from enriched mantle sources, having long-term low Sm/Nd and high Rb/Sr ratios, relative to bulk earth and depleted asthenospheric mantle. All lamproites are considered, on the basis of their geochemistry, to be derived from ancient mineralogically complex K–Ti–Ba–REE-rich veins, or metasomes, in the lithospheric mantle with, or without, subsequent contributions from recent asthenospheric or subducted components at the time of genesis. Lamproite primary magmas are considered to be relatively silica-rich (~50–60 wt.% SiO2), MgO-poor (3–12 wt.%), and ultrapotassic (~8–12 wt.% K2O) as exemplified by hyalo-phlogopite lamproites from the Leucite Hills (Wyoming) or Smoky Butte (Montana). Brief descriptions are given of the most important phreatomagmatic diamondiferous lamproite vents. The tectonic processes which lead to partial melting of metasomes, and/or initiation of magmatism, are described for examples of cratonic and orogenic lamproites. As each lamproite province differs with respect to its mineralogy, geochemical evolution, and tectonic setting there is no simple or common petrogenetic model for their genesis. Each province must be considered as the unique expression of the times and vagaries of ancient mantle metasomatism, coupled with diverse and complex partial melting processes, together with mixing of younger asthenospheric and lithospheric material, and, in the case of many orogenic lamproites, with Paleogene to Recent subducted material.

Les depots sedimentaires quaternaires et actuels de l'archipel de Kerguelen

1958 ◽  
Vol S6-VIII (2) ◽  
pp. 123-130 ◽  
Author(s):  
Edgar Aubert de la Rue
Keyword(s):  
Indian Ocean ◽  
Sea Level ◽  
The South ◽  
South Indian Ocean ◽  
Kerguelen Islands ◽  
Marine Deposits ◽  
South Indian ◽  
Eolian Deposits

Abstract The surface deposits of the Kerguelen islands in the south Indian Ocean comprise Quaternary and modern sediments found at elevations between sea level and 500 meters. They consist mainly of moraines, littoral marine deposits resulting from reworking of the moraines, torrential and fluvial alluvium, eolian deposits, andformations of organic origin (diatomaceous mud and peat).

scholarly journals Cadmium, copper and zinc in octopuses from Kerguelen Islands, Southern Indian Ocean

Polar Biology ◽  
1998 ◽  
Vol 19 (4) ◽  
pp. 264-271 ◽  
Author(s):  
P. Bustamante ◽  
Y. Cherel ◽  
F. Caurant ◽  
P. Miramand
Keyword(s):  
Indian Ocean ◽  
Southern Indian Ocean ◽  
Kerguelen Islands ◽  
Copper And Zinc

Platinum-group elements and the multistage metasomatic history of Kerguelen lithospheric mantle (South Indian Ocean)

2004 ◽  
Vol 208 (1-4) ◽  
pp. 195-215 ◽  
Author(s):  
Jean-Pierre Lorand ◽  
Guillaume Delpech ◽  
Michel Grégoire ◽  
Bertrand Moine ◽  
Suzanne Y O'Reilly ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Lithospheric Mantle ◽  
Platinum Group Elements ◽  
South Indian Ocean ◽  
South Indian ◽  
History Of ◽  
Platinum Group

Feldspar from carbonate-rich silicate metasomatism in the shallow oceanic mantle under Kerguelen Islands (South Indian Ocean)

Lithos ◽  
2004 ◽  
Vol 75 (1-2) ◽  
pp. 209-237 ◽  
Author(s):  
G. Delpech ◽  
M. Grégoire ◽  
Suzanne Y. O'Reilly ◽  
J.Y. Cottin ◽  
B. Moine ◽  
...  
Keyword(s):  
Indian Ocean ◽  
South Indian Ocean ◽  
Kerguelen Islands ◽  
South Indian

Crustal architecture and tectonic assembly of the Central Gneiss Belt, southwestern Grenville Province, Canada: a new interpretation

2000 ◽  
Vol 37 (2-3) ◽  
pp. 217-234 ◽  
Author(s):  
J WF Ketchum ◽  
A Davidson
Keyword(s):  
Structural Model ◽  
Hanging Wall ◽  
Mafic Rock ◽  
Grenville Province ◽  
The North ◽  
Rock Types ◽  
Structural Barrier ◽  
New Interpretation ◽  
Central Gneiss Belt ◽  
Tectonic Boundary

The Central Gneiss Belt, southwestern Grenville Province, is characterized by parautochthonous crust in the north and allochthonous lithotectonic domains in the south. Despite nearly two decades of study, the basal décollement to allochthonous domains transported from the southeast, known as the allochthon boundary thrust, has not been precisely located throughout much of the belt. Between Lake Nipissing and Georgian Bay where its surface trace is known, it separates 1.24 Ga Sudbury metadiabase in the footwall from eclogite remnants and 1.17-1.15 Ga coronitic olivine metagabbro confined to its hanging wall. On the premise that this relationship can be used to trace the allochthon boundary thrust elsewhere in the Central Gneiss Belt, we have sought to extend the known distribution of these mafic rock types, making use of field, petrographic, and geochemical criteria to identify them. New occurrences of all three mafic types are identified in a region extending from south of Lake Nipissing to western Quebec, and the mutually exclusive pattern of occurrence is maintained within this region. Structural trends and reconnaissance mapping of high-strain zones that appear to represent a structural barrier to the mafic suites suggest that the allochthon boundary thrust lies well to the north of its previously suggested location. Our preferred surface trace for it passes around the southern end of the Powassan batholith and through the town of North Bay before turning east to join up with the Lac Watson shear zone in western Quebec. This suggests that a large segment of "parautochthonous" crust lying north of, and including, the Algonquin domain is in fact allochthonous. The mutually exclusive distribution of the mafic suites points to significant separation of allochthonous and parautochthonous components prior to the Grenvillian orogeny, in accord with models of pre-Grenvillian continental rifting proposed by others. Despite a relative abundance of geological and geochronological data for the Central Gneiss Belt and a mafic rock distribution that appears to successfully locate a major tectonic boundary, we emphasize the need for additional field and laboratory work aimed at testing our structural model.

Sign in / Sign up

Export Citation Format

Share Document