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Full-Text Articles in Social and Behavioral Sciences
Eoarchaean Crustal Growth In West Greenland (Itsaq Gneiss Complex) And In Northeastern China (Anshan Area): Review And Synthesis, Allen P. Nutman, Vickie C. Bennett, Clark R L Friend, Frances Jenner, Yusheng Wan, Dunyi Liu
Eoarchaean Crustal Growth In West Greenland (Itsaq Gneiss Complex) And In Northeastern China (Anshan Area): Review And Synthesis, Allen P. Nutman, Vickie C. Bennett, Clark R L Friend, Frances Jenner, Yusheng Wan, Dunyi Liu
Faculty of Science - Papers (Archive)
Eoarchaean crust in West Greenland (the Itsaq Gneiss Complex, 3870-3600 Ma) is >80% by volume orthogneisses derived from plutonic tonalite-trondhjemite-granodiorite (TTG) suites,3850, c. 3810 and c. 3710 Mahave some compositional similarities to modern island arc basalts (IAB), suggesting their origin by hydrous fluxing of a suprasubduction-zone upper mantle wedge. Most of the Eoarchaean tonalites match in composition high-silica, low-magnesian adakites, whose petrogenesis is dominated by partial melting of garnetiferous mafic rocks at high pressure. However, associated with the tonalites are volumetrically minor more magnesian quartz diorites, whose genesis probably involved melting of depleted mantle to which some slab-derived component had …
Detrital Zircon Sedimentary Provenance Ages For The Eoarchaean Isua Supracrustal Belt Southern West Greenland: Juxtaposition Of An Imbricated Ca. 3700 Ma Juvenile Arc Against An Older Complex With 3920-3760 Ma Components, Allen P. Nutman, Clark R L Friend, Shane Paxton
Detrital Zircon Sedimentary Provenance Ages For The Eoarchaean Isua Supracrustal Belt Southern West Greenland: Juxtaposition Of An Imbricated Ca. 3700 Ma Juvenile Arc Against An Older Complex With 3920-3760 Ma Components, Allen P. Nutman, Clark R L Friend, Shane Paxton
Faculty of Science - Papers (Archive)
The amphibolite facies Eoarchaean Isua supracrustal belt (northern part of the Nuuk region, southern West Greenland) is dominated by strongly deformed metabasalts, with chert, banded iron formation, felsic volcanic and volcano-sedimentary rocks and minor gabbro and sedimentary carbonates. It comprises a suture zone between a northern terrane formed at ca. 3700 Ma and a southern one formed at ca. 3800 Ma. At the junction between these two terranes is a strongly tectonised, thin unit of metachert, BIF and carbonate-bearing rocks with minor detrital components, named the dividing sedimentary unit. Away from the belt, the northern terrane is dominated by ca. …
The Whole Rock Sm-Nd 'Age' For The 2825 Ma Ikkattoq Gneisses (Greenland) Is 800 Ma Too Young: Insights Into Archaean Ttg Petrogenesis, Clark R L Friend, Allen Phillip Nutman, Halfdan Baadsgaard, M John M Duke
The Whole Rock Sm-Nd 'Age' For The 2825 Ma Ikkattoq Gneisses (Greenland) Is 800 Ma Too Young: Insights Into Archaean Ttg Petrogenesis, Clark R L Friend, Allen Phillip Nutman, Halfdan Baadsgaard, M John M Duke
Faculty of Science - Papers (Archive)
The Ikkattoq gneisses of the Archaean gneiss complex in the Nuuk region, southern West Greenland, are the orthogneiss component within the amphibolite facies Tre Brodre terrane. They have mostly granodioritic compositions, with a small amount of quartz diorite. Sm-Nd isotopic data for a quartz diorite and five granodiorite Ikkattoq gneiss samples from within 5 km of the Ikkattoq (fjord) type locality yielded a regression with a slope equivalent to 2005 +/- 52 Ma (MSWD = 0.72). Regardless of the low MSWD, this cannot be the true age of the Ikkattoq gneisses, because all Ikkattoq gneisses yield U-Pb zircon dates of …
In Situ U-Pb, O And Hf Isotopic Compositions Of Zircon And Olivine From Eoarchaean Rocks, West Greenland: New Insights To Making Old Crust, Joe Hiess, Vickie C. Bennett, Allen P. Nutman, Ian S. Williams
In Situ U-Pb, O And Hf Isotopic Compositions Of Zircon And Olivine From Eoarchaean Rocks, West Greenland: New Insights To Making Old Crust, Joe Hiess, Vickie C. Bennett, Allen P. Nutman, Ian S. Williams
Faculty of Science - Papers (Archive)
The sources and petrogenetic processes that generated some of the Earth's oldest continental crust have been more tightly constrained via an integrated, in situ (U-Pb, O and Hf) isotopic approach. The minerals analysed were representative zircon from four Eoarchaean TTG tonalites and two felsic volcanic rocks, and olivine from one harzburgite/dunite of the Itsaq Gneiss Complex (IGC), southern West Greenland. The samples were carefully chosen from localities with least migmatisation, metasomatism and strain. Zircon was thoroughly characterized prior to analysis using cathodoluminescence, scanning electron, reflected and transmitted light imaging. The zircon from all but one sample showed only minor post-magmatic …
The Nagssugtoqidian Orogen In South-East Greenland: Evidence For Paleoproterozoic Collision And Plate Assembly, Allen Phillip Nutman, Feiko Kalsbeek, Clark R L Friend
The Nagssugtoqidian Orogen In South-East Greenland: Evidence For Paleoproterozoic Collision And Plate Assembly, Allen Phillip Nutman, Feiko Kalsbeek, Clark R L Friend
Faculty of Science - Papers (Archive)
The 200 km wide, east-west trending Paleoproterozoic mobile belt of the Ammassalik region of South-East Greenland contains a diverse assemblage of Paleoproterozoic and Archean rocks, variably affected by Paleoproterozoic deformations and high-grade low or high pressure metamorphism. By using previous field and geochemical data combined with new zircon dating and zircon trace element geochemistry, this mobile belt is confirmed as a 1870 to 1840 Ma collisional orogen, which contains one or more 1900 to 1880 Ma magmatic suites and northern and southern Archean basement terranes. The most studied 1900 to 1880 Ma magmatic suite is the Ammassalik Intrusive Complex, which …
Palaeoproterozoic And Archaean Gneiss Complexes In Northern Greenland: Palaeoproterozoic Terrane Assembly In The High Arctic, Allen Phillip Nutman, Peter Dawes, Feiko Kalsbeek, Mike Hamilton
Palaeoproterozoic And Archaean Gneiss Complexes In Northern Greenland: Palaeoproterozoic Terrane Assembly In The High Arctic, Allen Phillip Nutman, Peter Dawes, Feiko Kalsbeek, Mike Hamilton
Faculty of Science - Papers (Archive)
The Precambrian shield of northern Greenland has been investigated by SHRIMP U-Pb zircon dating of 14 orthogneisses and granitoids plus 5 metasediments, integrated with mapping by the Geological Survey of Denmark and Greenland and whole-rock Nd isotopic studies. The Inglefield Mobile Belt is a tract of Palaeoproterozoic sedimentation, plutonism, polyphase deformation and high-grade metamorphism that underlies Inglefield Land and northern Prudhoe Land. In the southern part of the belt at 78 degrees 30'N, the E-W-trending Sunrise Pynt Straight Belt is a high-grade, but structurally late, shear zone with contrasts in the geology on either side. South of the Sunrise Pynt …
~3,850 Ma Tonalites In The Nuuk Region, Greenland: Geochemistry And Their Reworking Within An Eoarchaean Gneiss Complex, Allen P. Nutman, Vickie C. Bennett, Clark R. L Friend, Kenji Horie, Hiroshi Hidaka
~3,850 Ma Tonalites In The Nuuk Region, Greenland: Geochemistry And Their Reworking Within An Eoarchaean Gneiss Complex, Allen P. Nutman, Vickie C. Bennett, Clark R. L Friend, Kenji Horie, Hiroshi Hidaka
Faculty of Science - Papers (Archive)
The Eoarchaean (>3,600 Ma) Itsaq Gneiss Complex of southern West Greenland is dominated by polyphase orthogneisses with a complex Archaean tectonothermal history. Some of the orthogneisses have c. 3,850 Ma zircons, and they vary from rare single phase metatonalites to more common complexly banded migmatites. This is due to heterogeneous strain, in situ anatexis and granitic veining superimposed during younger tectonothermal events. In the single-phase tonalites with c. 3,850 Ma zircon, oscillatory-zoned prismatic zircon is all 3,850 Ma old, but shows patchy ancient loss of radiogenic Pb. SHRIMP spot analyses and laser ablation ICP-MS depth profiling show that thin …
2635 Ma Amphibolite Facies Gold Mineralisation Near A Terrane Boundary (Suture?) On Storo, Nuuk Region, Southern West Greenland, Allen P. Nutman, Ole Christiansen, Clark R. L Friend
2635 Ma Amphibolite Facies Gold Mineralisation Near A Terrane Boundary (Suture?) On Storo, Nuuk Region, Southern West Greenland, Allen P. Nutman, Ole Christiansen, Clark R. L Friend
Faculty of Science - Papers (Archive)
Gold on Storø (in the Nuuk region of southern West Greenland) occurs in a slice of strongly deformed, amphibolite facies, Neoarchaean quartzo-feldspathic metasedimentary rocks and amphibolites in tectonic contact with the Eoarchaean Færingehavn terrane and the Meso- to Neoarchaean Akia terrane. The gold is associated with either löllingite (FeAs) + arsenopyrite or pyrrhotite, which belong with the amphibolite facies silicate mineral assemblages. Zircons were U/Pb dated by SHRIMP to constrain the timing of mineralisation. The 2700–2830 Ma oscillatory-zoned, high Th/U volcano-sedimentary zircon as whole grains and cores are interpreted to give the maximum depositional age of the rocks hosting the …
Complex 3670-3500 Ma Orogenic Episodes Superimposed On Juvenile Crust Accreted Between 3850 And 3690 Ma, Itsaq Gneiss Complex, Southern West Greenland, Clark R L Friend, Allen Phillip Nutman
Complex 3670-3500 Ma Orogenic Episodes Superimposed On Juvenile Crust Accreted Between 3850 And 3690 Ma, Itsaq Gneiss Complex, Southern West Greenland, Clark R L Friend, Allen Phillip Nutman
Faculty of Science - Papers (Archive)
The Itsaq Gneiss Complex of the Nuuk region, southern West Greenland, is dominated by 3850-3690 Ma tonalites intruded into and intercalated with lesser amounts of different ≥3850-3700 Ma supracrustal units. Published wholerock Sr and Nd isotopic studies demonstrate that the tonalites are juvenile crustal additions from a depleted mantle source. From our field studies and SHRIMP U/Pb zircon dating, we argue that this juvenile crustal accretion was spread over ca. 170 m.yr. (≥3850-3690 Ma). Following 3850-3690 Ma juvenile crustal accretion events, the evolution of the Itsaq Gneiss Complex continued with numerous crustal-reworking events between 3670 and 3500 Ma. Examples of …
Age, Petrogenesis And Metamorphism Of The Syn-Collisional Proven Igneous Complex, West Greenland, Kristine Thrane, J Baker, J Connelly, Allen Phillip Nutman
Age, Petrogenesis And Metamorphism Of The Syn-Collisional Proven Igneous Complex, West Greenland, Kristine Thrane, J Baker, J Connelly, Allen Phillip Nutman
Faculty of Science - Papers (Archive)
The Paleoproterozoic Prøven Igneous Complex (PIC) in West Greenland extends from ca. 72°15′ to 73°10′N, approximately 500 km north of the subduction-related intrusive complex in the core of the +1100 km wide, asymmetric collisional Nagssugtoqidian-Rinkian Orogen. A new U-Pb SHRIMP age for the PIC of 1869±9 Ma indicates that it intruded synchronously with the main collisional phase of the orogen into the passive margin side of the collision. Sm-Nd and Lu-Hf isotopic and A-type geochemical signatures are compatible with its derivation from melted Archean lower crustal material contaminated to varying degrees by pelitic sedimentary rocks of the Karrat Group. The …