Статті в журналах: "Proterozoic terrain"

1

O’Dea, M. G., G. S. Lister, T. Maccready, P. G. Betts, N. H. S. Oliver, K. S. Pound, W. Huang, R. K. Valenta, N. H. S. Oliver, and R. K. Valenta. "Geodynamic evolution of the Proterozoic Mount Isa terrain." Geological Society, London, Special Publications 121, no. 1 (1997): 99–122. http://dx.doi.org/10.1144/gsl.sp.1997.121.01.05.

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2

Santosh, M., and M. Yoshida. "The Archaean-Proterozoic terrain assembly in southern India." Journal of Southeast Asian Earth Sciences 14, no. 5 (December 1996): III. http://dx.doi.org/10.1016/s0743-9547(97)88148-2.

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3

Santosh, M., and M. Yoshida. "The Archaean-Proterozoic terrain assembly in southern India." Journal of African Earth Sciences 23, no. 2 (August 1996): III. http://dx.doi.org/10.1016/s0899-5362(97)86869-8.

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4

Santosh, M., and M. Yoshida. "The Archaean-Proterozoic terrain assembly in southern India." Journal of South American Earth Sciences 10, no. 3-4 (May 1997): III. http://dx.doi.org/10.1016/s0895-9811(97)90001-8.

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5

Jepsen, H. F., J. C. Escher, J. D. Friderichsen, and A. K. Higgins. "The geology of the north-eastern corner of Greenland - photogeological studies and 1993 field work." Rapport Grønlands Geologiske Undersøgelse 161 (January 1, 1994): 21–33. http://dx.doi.org/10.34194/rapggu.v161.8240.

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Late Archaean and Early Proterozoic crust-forming events in North-East and eastern North Greenland were succeeded by Middle Proterozoic sedimentation and volcanic activity; Late Proterozoic through Tertiary sedimentation was interrupted by several periods of tectonic activity, including the Caledonian orogeny in East Greenland and the Mesozoic deformation of the Wandel Hav mobile belt. Photogeological studies helped pinpoint areas of special interest which were investigated during the short 1993 field season. Insights gained during field work include: the nature of the crystalline basement terrain in the Caledonian fold belt, redefinition of the upper boundary of the Upper Proterozoic Rivieradal sandstones, revision of Caledonian nappe terminology, and the northern extension of the Caledonian Storstrømmen shear zone.

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6

Koroteev, Viktor A., Viktor M. Necheukhin, Artur A. Krasnobaev, and Elena N. Volchek. "Terrains of the main geodynamical types in the structures of Ural-Timan areal and the Eurasia North-Eastern segment." LITOSFERA, no. 6 (December 28, 2018): 779–96. http://dx.doi.org/10.24930/1681-9004-2018-18-6-779-796.

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Subject of study. Different points of view on the concept of structures of the terrain type and their role in the addition of orogenic belts are considered. Materials and methods. We used our own research and analysis of the latest publications about the Ural-Timan region and the Pacific belt, on the territory of the Northeast segment of Eurasia, as well as currently known isotope radiometric data. It was used also the result of geophysical seismotectonic and paleomagnetic explorations. Results. It has been established that in the composition of the Ural-Timan structural area, along with the Proterozoic and Paleozoic associations of the orogenic belts and the Riphean sedimentary series of protrusions of the Russian Plate, structural formations that correspond to the terrain of the continental crust take part. They are the most characteristic for the Ural orogenic belt, which belongs to the group of epiokean-type belts, associated with the transformation of ocean basins with the active participation of accretion and collision processes. The parametric features of these terrains include the ancient age characteristics of terrain rocks, their position in the belt structure, as well as the presence of relics of subhorizontal layered structural elements. The discordant blocks of migmatites, gneisses and other metamorphic rocks of Precambrian age, which make up the terrains, was the basis for the introduction of the term “terranes of the ancient continental crust”. By connection with the source, exotic and endemic, and simple and complex terrains are distinguished by structure. The geodynamics of including terrains of the ancient continental crust into the structure of orogenic belts is associated with horizontal movements of fragments of the ancient lithosphere in oceanic paleobasins to the periphery of the Russian Plate and their localization in belt structures. The formation of these terrains in the structures of the orogenic belts is completed by the formation of the intra-terrain massifs of granitoids and belts of volcanic-intrusive series. Supporters of a different methodology, dominant among researchers of the Pacific Belt of the Northeast Segment of Eurasia, refer to terrains all the structural elements that perform orogenic belts, because they believe that they have undergone horizontal movements and are in allochtonous occurrence. Conclusions. It has been established that in different geological provinces the term terrain has its own characteristics. This was the basis for the selection of two geodynamic types of terrains.

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7

Dawes, P. R., N. J. Soper, J. C. Escher, and R. P. Hall. "The northern boundary of the Proterozoic (Nagssugtoqidian) mobile belt of South-East Greenland." Rapport Grønlands Geologiske Undersøgelse 146 (December 31, 1989): 54–65. http://dx.doi.org/10.34194/rapggu.v146.8097.

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The Proterozoic mobile belt of South-East Greenland has been regarded as a classic example of amphibolite facies reworking of an Archaean granulite facies gneiss terrain. Its northern boundary has been interpreted as a transcurrent shear zone in which reworking was associated with major basic dyke emplacement. A re-examination of the northern boundary shows it to be a diffuse region more than 50 km wide in which retrogression, unrelated to dykes or shear zones, gradually intensifies southwards. Superimposed on this are discrete belts of retrogression associated with dykes and shear zones. The sense of displacement on the latter is compatible with thrusting of the northern Archaean block southwards over the reworked terrain of the mobile belt.

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8

Escher, J. C., and R. P. Hall. "The Niflheim thrust: a tectonic contact between granulite and amphibolite facies gneisses, South-East Greenland." Rapport Grønlands Geologiske Undersøgelse 146 (December 31, 1989): 66–69. http://dx.doi.org/10.34194/rapggu.v146.8098.

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The Niflheim thrust forms part of the northern boundary zone of the Proterozoic mobile belt of the Ammassalik region and defines the southernmost extent of granulite facies gneisses north-west of Sermilik. The thrust sharply separates grey amphibolite facies gneisses (footwall) from a thick and extensive unit of brown granulite facies gneisses, suggesting considerable lateral as well as vertical transport of the brown gneisses. Above the contact, the brown gneisses have only been weakly affected by deformation, whilst below the contact intensely folded and sheared grey gneisses indicate strong deformation of the upper part of the footwall sequence during thrusting. Asymmetry of folds below the contact and the E–W trending, gently north dipping thrust contact indicate a sinistral transpressional sense of movement with an up-to-the-south main component of transport. Three undeformed, discordant basic Proterozoic dykes in the grey gneisses of the footwall are truncated by the thrust and the thrust plane has been gently folded during a late stage of the regional Proterozoic deformation. Contrasts between high-grade mineralogy of Proterozoic dykes in the northern part of the Ammassalik region and lower grade, high crustal-level dykes of the grey gneiss terrain in the south are related to the regional thrusting from the north.

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9

Glukhov, A. N. "Base metal mineralization of the Kolyma terrain in Northeast Russia: Overview and genetic classification." LITHOSPHERE (Russia) 19, no. 5 (November 23, 2019): 717–30. http://dx.doi.org/10.24930/1681-9004-2019-19-5-717-730.

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Research subject. The Prikolyma terrain located in the Northeastern part ofRussia constitutes a long-lived Precambrian thrust-faulted structure hosting numerous Cu, Pb and Zn deposits of different types.Materials and methods. The mineralization of the terrain was examined during a course of research and exploration works over the 2007–2012. The rock geochemistry was studied using ICP-OES analysis at the Stuart Geochemistry and Essay laboratory (Moscow). The microprobe analysis of minerals was carried out at the facilities of the Far Eastern Branch of the Russian Academy of Sciences (Magadan) using a Camebax X-ray microanalyzer. The isotopic ratios of sulphur in sulphides were measured using a Finnigan MAT 253 isotope mass spectrometer.Results. The porphyry-copper deposit Nevidimka is represented by skarns and sulphide-quartz stockworks embedded in porphyry granites. The vein deposits Opyt and Glukhoye constitute sulphide-carbonate-quartz veins, the composition of which corresponds to copper-polymetallic ores of the peripheral parts of the copper-porphyry formation. These deposits feature a similar geochemistry and composition of sulphides and sulphur isotopes, which is characteristic of the Riphean complexes of the Prikolyma terrain. The stratiform Pb-Zn veins Nadezhda-3 and Khaya enclosed in Proterozoic dolomites represent parallel-bedding disseminated sulphides. The composition of these ores indicates their diagenetic origin. Tne stratiform copper deposit Oroyok is embedded in Proterozoic shales and can be referred to sediment-hosted copper deposits of a transgressive type.Conclusions. The diversity of Cu-Pb-Zn mineralization types in the Prikolyma terrain is established to have resulted from multiple cyclic changes of the geodynamic ore formation regime. During each such cycle, syngenetic mineralization was followed first by epigenetic and then by vein mineralization. The mobile, thrust-faulted structure caused repeated rejuvenation of ores, which inherited the geochemical features of hosting rocks.

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10

Ahmed, Zulfiqar. "Geochemical characterization of proterozoic upper crustal metamorphic terrain of southern Malakand Agency, Pakistan." Precambrian Research 46, no. 3 (February 1990): 181–94. http://dx.doi.org/10.1016/0301-9268(90)90001-7.

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11

Mall, A. P., and R. S. Sharma. "Coronas in olivine metagabbros from the Proterozoic Chotanagpur terrain at Mathurapur, Bihar, India." Lithos 21, no. 4 (July 1988): 291–300. http://dx.doi.org/10.1016/0024-4937(88)90034-5.

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12

Vijay Kumar, T., S. Jagadeesh, and S. S. Rai. "Crustal structure beneath the Archean–Proterozoic terrain of north India from receiver function modeling." Journal of Asian Earth Sciences 58 (September 2012): 108–18. http://dx.doi.org/10.1016/j.jseaes.2012.06.015.

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13

Hoal, B. G., R. E. Harmer, and B. M. Eglington. "Isotopic evolution of the Middle to Late Proterozoic Awasib Mountain terrain in southern Namibia." Precambrian Research 45, no. 1-3 (November 1989): 175–89. http://dx.doi.org/10.1016/0301-9268(89)90038-7.

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14

Hallberg, A. "Metal sources in the Early Proterozoic Svecofennian terrain of central Sweden: Pb isotope evidence." Mineralium Deposita 24, no. 4 (October 1989): 250–57. http://dx.doi.org/10.1007/bf00206387.

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15

Sims, John P., Paul H. G. M. Dirks, Chris J. Carson, and Chris J. L. Wilson. "The structural evolution of the Rauer Group, East Antarctica: mafic dykes as passive markers in a composite Proterozoic terrain." Antarctic Science 6, no. 3 (September 1994): 379–94. http://dx.doi.org/10.1017/s0954102094000581.

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Archaean gneisses in the Rauer Group of islands, East Antarctica, record a prolonged history of high-grade deformational episodes, many of which predate that identified in mid-Proterozoic gneisses. Eleven generations of mafic dykes, belonging to discrete chemical suites, have been used as relative time markers to constrain this deformational history. Based on the timing of intrusion with respect to structures, dykes in the Rauer Group have been correlated with largely undeformed and dated dyke suites in the adjacent Vestfold Hills. This has allowed absolute ages to be inferred for the early- to mid-Proterozoic mafic dyke suites in the Rauer Group, and a correlation of the interspersed structural events. Most structures in the Rauer Group, however, developed in response to high-grade progressive deformation at approximately 1000 Ma. During this deformational episode, strains were repeatedly partitioned into sub-vertical, noncoaxial, high-strain zones recording NW-directed sinistral transpression, that separated zones of lower strain dominated by coaxial folding with axes parallel to the shear direction. Three additional mafic dyke suites intruded during this deformation which was followed by three stages of brittle-ductile deformation and a final suite of lamprophyre dykes. Due to the numerous intrusive time markers, the Rauer Group serves as an excellent illustration of how complicated gneiss terrains may be.

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16

Kroonenberg, S. B., E. W. F. de Roever, L. M. Fraga, N. J. Reis, T. Faraco, J. M. Lafon, U. Cordani, and T. E. Wong. "Paleoproterozoic evolution of the Guiana Shield in Suriname: A revised model." Netherlands Journal of Geosciences - Geologie en Mijnbouw 95, no. 4 (May 12, 2016): 491–522. http://dx.doi.org/10.1017/njg.2016.10.

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AbstractThe Proterozoic basement of Suriname consists of a greenstone–tonalite–trondhjemite–granodiorite belt in the northeast of the country, two high-grade belts in the northwest and southwest, respectively, and a large granitoid–felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U–Pb and Pb–Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2–1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.

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17

Drury, S. A. "SPOT image data as an aid to structural mapping in the southern Aravalli Hills of Rajasthan, India." Geological Magazine 127, no. 3 (May 1990): 195–207. http://dx.doi.org/10.1017/s0016756800014485.

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AbstractThe 10 to 20 m resolution of SPOT image data, together with their potential for stereoscopic viewing, provides an excellent base for geological mapping inremote and rugged terrain that is akin to high-level aerial photographs. Their large format (60 × 60 km) also gives the advantage of synoptic coverage that ranks with images from the Landsat series of satellites. Use of stereo pairs of single-band SPOT images has enabled some revision of existing geological maps of the southern Aravalli Hills in Rajasthan at a scale of 1:100000, and has added significantly to knowledge of their complex mid-Proterozoic structure. In particular, many possibly early low-angled faults have been discovered, together with the tectonic nature of a major terrain boundary and much detail of intricate structures has been added in the more remote areas. The potentialfor lithological discrimination of multispectral SPOT data is severely limited by its restricted coverage of geologically important spectral features, and it is far surpassed by that of Landsat Thematic Mapper data, which would have been capable of more comprehensive lithofacies reconnaissance, had they been available.

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18

LEELANANDAM, C., K. BURKE, L. D. ASHWAL, and S. J. WEBB. "Proterozoic mountain building in Peninsular India: an analysis based primarily on alkaline rock distribution." Geological Magazine 143, no. 2 (March 2006): 195–212. http://dx.doi.org/10.1017/s0016756805001664.

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Peninsular India was assembled into a continental block c. 3 million km2 in area as a result of collisions throughout the length of a 4000 km long S-shaped mountain belt that was first recognized from the continuity of strike of highly deformed Proterozoic granulites and gneisses. More recently the recognition of a variety of tectonic indicators, including occurrences of ophiolitic slivers, Andean-margin type rocks, a collisional rift and a foreland basin, as well as many structural and isotopic age studies have helped to clarify the history of this Great Indian Proterozoic Fold Belt. We here complement those studies by considering the occurrence of deformed alkaline rocks and carbonatites (DARCs) in the Great Indian Proterozoic Fold Belt. One aim of this study is to test the recently published idea that DARCs result from the deformation of alkaline rocks and carbonatites (ARCs) originally intruded into intra-continental rifts and preserved on rifted continental margins. The suggestion is that ARCs from those margins are transformed into DARCs during continental, or arc–continental, collisions. If that idea is valid, DARCs lie on rifted continental margins and on coincident younger suture zones; they occur in places where ancient oceans have both opened and closed. Locating sutures within mountain belts has often proved difficult and has sometimes been controversial. If the new idea is valid, DARC distributions may help to reduce controversy. This paper concentrates on the Eastern Ghats Mobile Belt of Andhra Pradesh and Orissa, where alkaline rock occurrences are best known. Less complete information from Kerala, Tamil Nadu, Karnataka, West Bengal, Bihar and Rajasthan has enabled us to define a line of 47 unevenly distributed DARCs with individual outcrop lengths of between 30 m and 30 km that extends along the full 4000 km length of the Great Indian Proterozoic Fold Belt. Ocean opening along the rifted margins of the Archaean cratons of Peninsular India may have begun by c. 2.0 Ga and convergent plate margin phenomena have left records within the Great Indian Proterozoic Fold Belt and on the neighbouring cratons starting at c. 1.8 Ga. Final continental collisions were over by 0.55 Ga, perhaps having been completed at c. 0.75 Ga or at c. 1 Ga. Opening of an ocean at the Himalayan margin of India by c. 0.55 Ga removed an unknown length of the Great Indian Proterozoic Fold Belt. In the southernmost part of the Indian peninsula, a line of DARCs, interpreted here as marking a Great Indian Proterozoic Fold Belt suture, can be traced within the Southern Granulite Terrain almost to the Achankovil-Tenmala shear zone, which is interpreted as a strike-slip fault that also formed at c. 0.55 Ga.

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19

Koul, Sohan L., A. R. Wilde, and Awtar K. Tickoo. "A thermal history of the Proterozoic East Alligator River Terrain, N.T., Australia: a fission track study." Tectonophysics 145, no. 1-2 (January 1988): 101–11. http://dx.doi.org/10.1016/0040-1951(88)90319-8.

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20

Harley, Simon L. "Mg-Al yttrian zirconolite in a partially melted sapphirine granulite, Vestfold Hills, East Antarctica." Mineralogical Magazine 58, no. 391 (June 1994): 259–69. http://dx.doi.org/10.1180/minmag.1994.058.391.08.

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AbstractA new compositional variety of zirconolite characterized by high Mg, Al, Y2O3 and REE, and low Fe is described from a sapphirine granulite xenolith entrained in an intrusive norite body which was emplaced into the late Archaean (2520–2480 Ma) Vestfold Hills high-grade terrain during the early Proterozoic. The zirconolite, and similarly Mg-Al rich perrierite-(Ce), formed as a result of sanidinite facies partial melting of the particularly magnesian and aluminous sapphirine granulite xenolith during its incorporation into the c. 1170°C basic magma at c. 2240 Ma. The high REE compared to Al cations require that a previously unrecognized coupled substitution:occurs in this zirconolite. Full chemical analyses are presented for zirconolite and perrierite from this unique occurrence.

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21

Ray, Yogesh, Subhajit Sinha, and Sumit K. Ghosh. "Provenance of the Proterozoic Lesser Himalayan siliciclastics, northwest Himalaya, India: Implications to terrain accretion and crustal evolution." Geosystems and Geoenvironment 1, no. 2 (May 2022): 100016. http://dx.doi.org/10.1016/j.geogeo.2021.100016.

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22

White, S., H. L. M. Van Roermund, and M. A. Harings. "EMP chemical age dating of monazites from a complex terrain: The Paleo-Proterozoic of broken hill, Australia." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A699. http://dx.doi.org/10.1016/j.gca.2006.06.1518.

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23

Bologna, Mauricio S., Gary D. Egbert, Antonio L. Padilha, Marcelo B. Pádua, and Ícaro Vitorello. "3-D inversion of complex magnetotelluric data from an Archean-Proterozoic terrain in northeastern São Francisco Craton, Brazil." Geophysical Journal International 210, no. 3 (June 17, 2017): 1545–59. http://dx.doi.org/10.1093/gji/ggx261.

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24

Spray, John G., and Lyle A. Burgess. "Landsat MSS imagery applied to geological investigation of the Norseman area granitoid–greenstone terrain, southeast Yilgarn Block, Western Australia." Geological Magazine 122, no. 6 (November 1985): 587–94. http://dx.doi.org/10.1017/s0016756800032003.

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AbstractInteractively processed Landsat MSS imagery has been used as an aid to studying the regional geology of approximately 10 800 km2 of terrain at the southeast margin of the Archaean Yilgarn Block in Western Australia. The technique proved successful in extending positions of known lithological contacts and lineaments into poorly exposed, inaccessible areas and in revealing new geological features, especially faults, previously unrecognized at ground level. During this investigation the distribution of granitoids and greenstones was more precisely defined, internal greenstone structures highlighted and three main fault trends were identified: (1) NW–NNW and (2) ENE, both within Archaean shield, and (3) NE–NNE within the transition to adjacent Proterozoic mobile belt. In order for the most information to be extracted from Landsat MSS images it is recommended that, whenever possible, image processing should follow ground-based studies as well as precede them, and that field geologist and Landsat specialist should work at the image processing system together.

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25

Hicock, Stephen R., Fridrik J. Kristjansson, and David R. Sharpe. "Carbonate till as a soft bed for Pleistocene ice streams on the Canadian Shield north of Lake Superior." Canadian Journal of Earth Sciences 26, no. 11 (November 1, 1989): 2249–54. http://dx.doi.org/10.1139/e89-191.

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Silty carbonate till derived from erosion of Paleozoic carbonate and Proterozoic rocks within and adjacent to Hudson Bay covers extensive areas of the Canadian Shield north of Lake Superior. It is hypothesized that this carbonate till could have acted as low-resistance substrata for overriding ice streams by deforming and (or) supporting high subglacial water pressures. Contrary to assumptions presented in some current models for ice flow within the Laurentide Ice Sheet, it need not be assumed that Shield terrain in these areas acted as a rigid bed, generating large basal shear stresses and inhibiting ice flow. Indeed, erratic-dispersal patterns, long-distance glacial transport, and splayed patterns of ice-flow indicators in areas of thick till cover may be better explained by rapid ice-flow events or ice streams, enhanced by the thickness, distribution, impermeability, and susceptibility to deformation of fine carbonate till.

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26

BHATTACHARYA, S., RAJIB KAR, S. MISRA, and W. TEIXEIRA. "Early Archaean continental crust in the Eastern Ghats granulite belt, India: isotopic evidence from a charnockite suite." Geological Magazine 138, no. 5 (September 2001): 609–18. http://dx.doi.org/10.1017/s0016756801005702.

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The Eastern Ghats granulite belt of India has traditionally been described as a Proterozoic mobile belt, with probable Archaean protoliths. However, recent findings suggest that synkinematic development of granulites took place in a compressional tectonic regime and that granulite facies metamorphism resulted from crustal thickening. The field, petrological and geochemical studies of a charnockite massif of tonalitic to trondhjemitic composition, and associated rocks, document granulite facies metamorphism and dehydration partial melting of basic rocks at lower crustal depths, with garnet granulite residues exposed as cognate xenoliths within the charnockite massif. The melting and generation of the charnockite suite under granulite facies conditions have been dated c. 3.0 Ga by Sm–Nd and Rb–Sr whole rock systematics and Pb–Pb zircon dating. Sm–Nd model dates between 3.4 and 3.5 Ga and negative epsilon values provide evidence of early Archaean continental crust in this high-grade terrain.

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27

Meng, Hua Jun, and Jian Ping Qiao. "The Spatial Distribution Characteristics of Seismic Induced Geo-Hazards and Ground Damage Classification in Baisha River." Advanced Materials Research 594-597 (November 2012): 1727–33. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1727.

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The Baisha river basin was extremely destroyed by the Wenchuan earthquake. This paper extracted the seismic-induced geological disasters data about 26km2 within an area of 368.25km2 by remote sensing interpretation and field investigation. This paper used arcgis to analysis these data, and divided the basin into several belts or zones base on slope, aspect, elevation and stratum lithology. The geo-hazard distribution analysis model was built to find some correlation between disaster distribution and geological factors such as terrain, stratum lithology and geomorphology by comparing among the parameters Ps, Ph, and Pc. The results show that most hazards occur where the slope between 30° and 50°, or aspect range is112.5° to 202.5°, and or the elevation between1140m and 3140m, the stratum lithology are the Huangshuihe group and The Middle Proterozoic common granite. At last the research zone is classified into four levels base on ground destroyed grade, and results show that the belts of most hazards located are not always the one destroyed most heavily.

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28

Chadwick, B., P. R. Dawes, J. C. Escher, C. R. L. Friend, R. P. Hall, F. Kalsbeek, T. F. D. Nielsen, A. P. Nutman, N. J. Soper, and V. N. Vasudev. "The Proterozoic mobile belt in the Ammassalik region, South-East Greenland (Ammassalik mobile belt): an introduction and re-appraisal." Rapport Grønlands Geologiske Undersøgelse 146 (December 31, 1989): 5–12. http://dx.doi.org/10.34194/rapggu.v146.8089.

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The Ammassalik mobile belt is characterised by a regional layer cake structure of tectonically interleaved sheets of quartzo-feldspathic orthogneisses and supracrustal rocks. The sheets of supracrustal rocks are most abundant in the north of the belt and they include semi-pelitic kyanite-sillimanite gneisses, graphitic schists, marble, amphibolites and local peridotite. The sheets are regarded as parts of a disrupted supracrustal sequence, here termed the Siportoq supracrustal association. Preliminary isotopic age data suggest that most of the orthogneisses are late Archaean, although some have early Proterozoic ages. The Siportoq supracrustal association has yielded an early Proterozoic age. Amphibolite dyke swarms were emplaced at various stages in the evolution of the mobile belt. The Ammassalik belt has an ill-defined northern limit marked by heterogeneous retrogression of a granulite facies terrain up to 100 km wide. Most of the belt is at amphibolite facies, with its southern limit lying to the south of the area considered here. The structure in the south is dominated by nappes and shear zones dipping NE within a wide tract of late Archaean orthogneisses intruded by amphibolite dyke swarms with relatively well preserved primary characteristics. The structure in the north is characterised by more pervasive deformation which gave rise to complex sequences of thrusting and nappe development propagating from the north. Large domes were superimposed on the nappe pile, perhaps as buoyancy phenomena. The dioritic Ammassalik Intrusive Complex (c. 1885 Ma) with its granulite facies assemblages is regarded as a late kinematic phenomenon. Major post-tectonic complexes of granite, diorite and gabbro (c. 1580 Ma) were intruded at a high level well after the close of the tectonism in the Ammassalik mobile belt.

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29

Vry, J. K., and I. Cartwright. "Sapphirine-kornerupine rocks from the Reynolds Range, central Australia: constraints on the uplift history of a Proterozoic low pressure terrain." Contributions to Mineralogy and Petrology 116, no. 1-2 (March 1994): 78–91. http://dx.doi.org/10.1007/bf00310691.

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30

Schärer, U., T. E. Krogh, R. J. Wardle, B. Ryan, and S. S. Gandhi. "U–Pb ages of early and middle Proterozoic volcanism and metamorphism in the Makkovik Orogen, Labrador." Canadian Journal of Earth Sciences 25, no. 7 (July 1, 1988): 1098–107. http://dx.doi.org/10.1139/e88-107.

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Zircon U–Pb dating on rhyolites from three different localities in the upper Aillik group, a volcano-sedimentary sequence of the Makkovik Orogen in Labrador, indicates two distinct pulses of volcanic activity at about 1860 and 1807 Ma. The individual rhyolite ages of [Formula: see text], 1856 ± 2, and 1807 ± 3 Ma are 40–150 Ma older than Rb–Sr ages determined previously on the same rocks. A slight scatter of zircon data observed for one of the rhyolites and the presence of old zircon cores suggest that the felsic magmas were derived in part from older continental material. Analyses of monazite and titanite from two anatectic rocks, a migmatite and leucogranite from a gneiss terrain adjacent to the supracrustals, document a period of high-grade metamorphism in the interval 1794 ± 2 to 1761 ± 2 Ma. This period is considered the terminal phase of the Makkovikian Orogeny. Zircons in the migmatite yield minimum ages ranging from about 1800 to 2340 Ma, indicating a derivation from latest Archean to early Proterozoic basement rocks.Zircon dating on a rhyolite from the Bruce River Group within the ~1650 Ma old Trans-Labrador batholith yields an age of 1649 ± 1 Ma. This age suggests that Bruce River acid volcanism was related to Trans-Labrador batholith emplacement.

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Doig, Ronald. "Rb–Sr geochronology and metamorphic history of Proterozoic to early Archean rocks north of the Cape Smith Fold Belt, Quebec." Canadian Journal of Earth Sciences 24, no. 4 (April 1, 1987): 813–25. http://dx.doi.org/10.1139/e87-079.

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The Churchill Province north of the Proterozoic Cape Smith volcanic fold belt of Quebec may be divided into two parts. The first is a broad antiform of migmatitic gneisses (Deception gneisses) extending north from the fold belt ~50 km to Sugluk Inlet. The second is a 20 km wide zone of high-grade metasedimentary rocks northwest of Sugluk Inlet. The Deception gneisses yield Rb–Sr isochron ages of 2600–2900 Ma and initial ratios of 0.701–0.703, showing that they are Archean basement to the Cape Smith Belt. The evidence that the basement rocks have been isoclinally refolded in the Proterozoic is clear at the contact with the fold belt. However, the gneisses also contain ubiquitous synclinal keels of metasiltstone with minor metapelite and marble that give isochron ages less than 2150 Ma. These ages, combined with low initial ratios of 0.7036, show that they are not part of the basement, as the average 87Sr/86Sr ratio for the basement rocks was about 0.718 at that time.The rocks west of Sugluk Inlet consist mainly of quartzo-feldspathic sediments, quartzites, para-amphibolites, marbles, and some pelite and iron formation. In contrast to the Proterozoic sediments in the Deception gneisses, these rocks yield dates of 3000–3200 Ma, with high initial ratios of 0.707–0.714. These initial ratios point to an age (or a provenance) much greater than that of the Archean Deception gneisses. The rocks of the Sugluk terrain are intruded by highly deformed sills of granitic rocks with ages of about 1830 Ma, demonstrating again the extent and severity of the Proterozoic overprint. The eastern margin of this possibly early Archean Sugluk block is a discontinuity in age, lithology, and geophysical character that could be a suture between two Archean cratons. It is not known if such a suturing event is of Archean age, or if it is related to the deformation of the Cape Smith Fold Belt.Models of evolution incorporating both the Cape Smith Belt and the Archean rocks to the north need to account for the internal structure of the fold belt, the continental affinity of many of the volcanic rocks, the continuity of basement around the eastern end of the belt, and the increase in metamorphism through the northern part of the belt into a broad area to the north. The Cape Smith volcanic rocks may have been extruded along a continental rift, parallel to a continental margin at Sugluk. Continental collison at Sugluk would have thrust the older and higher grade Sugluk rocks over the Deception gneisses, produced the broad Deception antiform, and displaced the Cape Smith rocks to the south in a series of north-dipping thrust slices.

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32

Jones, Stacie, Kurt Kyser, Matthew Leybourne, Robin Mackie, Adrian Fleming, and Daniel Layton-Matthews. "Paragenesis of gold mineralization at the Kiyuk Lake Project, Kivalliq Region, Nunavut, Canada." Canadian Mineralogist 59, no. 5 (September 1, 2021): 1133–65. http://dx.doi.org/10.3749/canmin.2000058.

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ABSTRACT Exploration for gold in Nunavut has been primarily focused on Archean greenstone belts in the north and coastal regions of the territory, resulting in large areas of underexplored terrain in the south. The Kiyuk Lake property is located in the underexplored southwest corner of the Kivalliq Region of Nunavut within the Hearne domain of the ∼1.9 Ga western Churchill Province. The property is hosted by Proterozoic calc-silicate and clastic sedimentary units of the Hurwitz Group (<2.4–1.9 Ga) and the unconformably overlying Kiyuk Group (1.9–1.83 Ga). Gold mineralization in Proterozoic sedimentary rocks is rare in the Canadian Shield, so the Rusty Zone at Kiyuk Lake presents a unique opportunity to study the enigmatic gold mineralization hosted in such sedimentary rocks. Mineralization at the Rusty Zone is hosted by an immature lithic wacke cut by thin intermediate dikes that are associated with hydrothermal breccias composed of Fe-carbonate, calcite, calcic-amphibole, Fe-sulfide, Fe-oxide minerals, and gold. Textural and timing relationships suggest that the gold mineralization is post-sedimentary and syn- to post-intrusion of intermediate dikes. Stable isotope thermometry suggests that mineralization took place between 450 and 600 °C, and geochronological studies indicate that the intrusion and mineralization occurred before or about 1.83 Ga. Using basement breaching thrusts faults as conduits to the surface, over-pressurization along a later normal fault is thought to be the primary cause for the localized breccia pipe that controls gold mineralization. The hydrothermal fluids are postulated to be volatile-rich aqueous solutions exsolved from a source of cooling magmas at depth. Although sub-economic at present, the occurrence of high-grade gold in a Paleoproterozoic basin such as Kiyuk Lake could signal a new opportunity for exploration for gold in the Canadian Shield.

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Raza, Mahshar, MohdShamim Khan, and MohdSafdare Azam. "Plate-plume-accretion tectonics in Proterozoic terrain of northeastern Rajasthan, India: Evidence from mafic volcanic rocks of north Delhi fold belt." Island Arc 16, no. 4 (December 2007): 536–52. http://dx.doi.org/10.1111/j.1440-1738.2007.00581.x.

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34

Prathigadapa, Raju, Subrata Das Sharma, and Durbha Sai Ramesh. "Seismic Evidence for Proterozoic Collisional Episodes along Two Geosutures within the Southern Granulite Province of India." Lithosphere 2020, no. 1 (October 15, 2020): 1–20. http://dx.doi.org/10.2113/2020/8861007.

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Abstract The Southern Granulite Province of India had witnessed episodes of multiple tectonic activities, leading to sparsely preserved surface geological features. The present study is focused on unraveling the geodynamic evolution of this terrain through measurement of Moho depth and Vp/Vs ratio using data from a large number of broadband seismic stations. These results unambiguously establish three domains distinct in Moho depth and crustal composition. An intermediate to felsic crust with a 7–10 km step-in-Moho is delineated across the Moyar–Bhavani region. Anomalously high felsic crust with abrupt jump in Moho (~8–10 km) together with a dipping feature at deeper level characterizes the transition from eastern to southern segments of the Jhavadi–Kambam–Trichur region. By contrast, the central zone hosting the Palghat–Cauvery shear zone records uniform felsic crust and flat Moho. Drawing analogy from similar results in different parts of the globe, juxtaposition of petrologically dissimilar crustal blocks characterized by varied depths to the Moho is argued to point towards unambiguous presence of two distinct geosutures in the study area: one along the Moyar–Bhavani region and the other across the Jhavadi–Kambam–Trichur. This inference is corroborated by the presence of layered meta-anorthosite, related rock suites, and mafic-ultramafic bodies, supporting the view of a suprasubduction setting in the Moyar–Bhavani region. The Jhavadi–Kambam–Trichur area is marked by operation of the Wilson cycle by way of sparsely preserved geological features such as the presence of ophirags (ophiolite fragments), alkali syenites, and carbonatites. Geochronological results suggest that the suturing along Moyar–Bhavani took place during the Paleoproterozoic and that along Jhavadi–Kambam–Trichur was during the late Neoproterozoic.

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35

Grew, Edward S., and W. I. Manton. "A new correlation of sapphirine granulites in the indo-antarctic metamorphic terrain: Late proterozoic dates from the eastern ghats province of India." Precambrian Research 33, no. 1-3 (September 1986): 123–37. http://dx.doi.org/10.1016/0301-9268(86)90018-5.

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36

RONCATO, Jorge, Ana Luiza de CARVALHO ALMEIDA, Bárbara MACEDO, and Matheus OLIVEIRA. "ANÁLISE GEOFÍSICA DA REGIÃO DO RIO CONCEIÇÃO, QUADRILÁTERO FERRÍFERO, ASSOCIADOS A DADOS DE CAMPO, PETROGRÁFICOS E DE IMAGENS AÉREAS." Geosciences = Geociências 39, no. 1 (May 19, 2020): 47–63. http://dx.doi.org/10.5016/geociencias.v39i1.14613.

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The Quadrilátero Ferrífero region, located in the southeast portion of the São Francisco Craton, is one of the main metallogenic provinces in Brazil. Fieldwork, petrography, high-resolution airborne geophysics (magnetic and gamma-ray spectrometry data), and aerial images allowed us to produce a new map at the 1:25,000 scale, with important contributions in the lithotypes detailing, understanding of the geological structures and relationship between the different stratigraphic units. Interpretation of airborne geophysical data integrated with field structural and lithological observations were successfully employed in the creation of the litho-structural framework in a poorly exposed Proterozoic and Archean terrain. Airborne gamma-ray spectrometry data aided in the mapping process in areas with regolith cover including erosional ridges. The magnetic total derivative image revealed regional and local structures. In addition, our work details the units of occurrence of Rio das Velhas and Minas Supergroup. The aerial coverage of the Mindá and Santa Quitéria formations strongly increased, as well as the area of the Cauê Formation was better defined. The new geological map provides many improvements over the pre-existing maps. New lithological facies and structures were identified and others become more visible and lithologicalboundaries are refined or confirmed.

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37

Kuzmin, S. B., S. I. Shamanova, and I. A. Belozertseva. "Altitudinal zonation of landscapes on the local testing area in the southern Baikal region." Izvestiya Rossiiskoi akademii nauk. Seriya geograficheskaya, no. 3 (June 25, 2019): 105–15. http://dx.doi.org/10.31857/s2587-556620193105-115.

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Today identification of altitudinal zones of landscapes in local areas, especially in mountainous areas, is inextricably linked with the creation of digital terrain models and their geoinformation interpretation. We have considered the altitudinal zonation of landscapes on the Mamai model testing area, located on the Northern macroslope of the Khamar-Daban Ridge and in the Tankhoi coastal plain of the Baikal Lake. The special geoinformation software, partially modernized during the works, was used. Landscapes were studied by their main components: relief and geomorphological processes, soils and soil-forming processes, vegetation. The landscapes of the testing area are represented by three main groups: 1) goltsy altitudinal and mountain-taiga landscapes of the Khamar-Daban Ridge on the crystalline metamorphic rocks of the khungurul series of the lower Proterozoic age and granites of the Khamar-Daban and Sayan intrusive complexes of the upper Proterozoic and lower Paleozoic, respectively; 2) taiga and meadow-marsh landscapes of the Tankhoi plain on loose sediments of the Late Pliocene and Quaternary ages; 3) intrazonal landscapes within transverse mountain river valleys on the Late Pleistocene and Neo-Pleistocene and modern loose sediments. The base of the identification of altitudinal zones of the landscape is layers of a relief. But the relief is a fairly static component of the landscape, its invariant structure change for tens or hundreds of thousands of years. To determine a more detailed and dynamic structure of the altitudinal zonation, we use other components: soils and vegetation. Changes in the invariant structure of the soil cover occur for thousands or tens of thousands of years, and of the vegetation cover – for hundreds or thousands of years. Features of the landscapes structure and characteristics of their main components allowed us to allocate six altitudinal zones in the testing area: goltsy altitudinal, subgoltsy altitudinal, low-mountain, foothill, foothill-plain, and coastal-plain. The intrazonal landscapes of transverse mountain river valleys, which violate the normal structure of the altitudinal zonation, are singled out as a separate type.

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38

Dongre, A., N. V. Chalapathi Rao, and G. Kamde. "Limestone Xenolith in Siddanpalli Kimberlite, Gadwal Granite‐Greenstone Terrain, Eastern Dharwar Craton, Southern India: Remnant of Proterozoic Platformal Cover Sequence of Bhima/Kurnool Age?" Journal of Geology 116, no. 2 (March 2008): 184–91. http://dx.doi.org/10.1086/529154.

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39

Hogarth, D. D. "Chemical Composition of Fluorapatite and Associated Minerals from Skarn Near Gatineau, Quebec." Mineralogical Magazine 52, no. 366 (June 1988): 347–58. http://dx.doi.org/10.1180/minmag.1988.052.366.06.

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AbstractSixteen fluorapatite specimens from regional skarns in granulite terrain were associated with Al-zoned diopside ± scapolite ± actinolite ± calcite(+ rare phlogopite). Apatite was low in Ce (ave. 0.19% Ce2O3) and enriched in LREE relative to HREE (La/Yb = 31 to 74 in 4 specimens). Some specimens showed small negative Eu anomalies and some crystals were zoned in REE. SrO averaged 0.36%. The mineral contained some carbonate (ave. 0.5% CO2 in 5 specimens), appreciable silica (ave. 0.5%), and variable sulphate (0.1 to 1.2% SO3). Excess charge due to S6+ was largely compensated by Si4+. Chlorine was minor and F accounted for 75–98% of the F, Cl and OH ions. Apatite from marble lacking amphiboles and pyroxenes has a similar chemical composition, but apatite from later carbonatite and fenite contains more Ce and Sr. Apatite from Gatineau fenite, Gatineau carbonatite and world-wide siliceous igneous rock generally contains less S. Apatite from Gatineau skarns normally contains more Cl and less S than that from phosphorite. Magnesian marble was silicated to skarn by reaction with siliceous gneiss. Phosphorus, REE, and Sr were removed from nearby rocks and transported in aqueous, carbonated solutions containing minor amounts of F, Cl and S at granulite-facies conditions. Apatite and calcite precipitation took place in skarns and marble during the Grenville (Proterozoic) orogeny.

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40

Tomson, J. K., Y. J. Bhaskar Rao, T. Vijaya Kumar, and J. Mallikharjuna Rao. "Charnockite genesis across the Archaean–Proterozoic terrane boundary in the South Indian Granulite Terrain: Constraints from major–trace element geochemistry and Sr–Nd isotopic systematics." Gondwana Research 10, no. 1-2 (August 2006): 115–27. http://dx.doi.org/10.1016/j.gr.2005.11.023.

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Mishra, D. C., and V. Vijaya Kumar. "Evidence for Proterozoic Collision from Airborne Magnetic and Gravity Studies in Southern Granulite Terrain, India and Signatures of Recent Tectonic Activity in the Palghat Gap." Gondwana Research 8, no. 1 (January 2005): 43–54. http://dx.doi.org/10.1016/s1342-937x(05)70261-6.

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42

de Wit, M. J., S. Bowring, R. Buchwaldt, F. Ö. Dudas, D. MacPhee, G. Tagne-Kamga, N. Dunn, A. M. Salet, and D. Nambatingar. "Geochemical reconnaissance of the Guéra and Ouaddaï Massifs in Chad: evolution of Proterozoic crust in the Central Sahara Shield." South African Journal of Geology 124, no. 2 (June 1, 2021): 353–82. http://dx.doi.org/10.25131/sajg.124.0048.

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Abstract In 1964, W.Q. Kennedy suggested that the crust of Saharan Africa is different from the rest of Africa. To date, the geologic evolution of this region remains obscure because the age and composition of crystalline basement are unknown across large sectors of the Sahara. Most of Africa comprises Archaean cratons surrounded by Palaeo- to Mesoproterozoic orogenic belts, which together constitute Africa’s three major shields (the Southern, Central and West African Shields), finally assembled along belts of Pan-African rocks. By contrast, central Saharan Africa (5.3x106 km2), an area just over half the size of Europe, is considered either as a Neoproterozoic region constructed of relatively juvenile crust (0.5 to 1.0 Ga), or as an older (North African) shield that was reactivated and re-stabilized during that time, a period commonly referred to as “Pan African”. Here, using U-Pb zircon age determinations and Nd isotopic data, we show that remote areas in Chad, part of the undated Darfur Plateau stretching across ¾ million km2 of the central Sahara, comprise an extensive Neoproterozoic crystalline basement of pre-tectonic gabbro-tonalite-granodiorite and predominantly post-tectonic alkali feldspar granites and syenites that intruded between ca. 550 to 1050 Ma. This basement is flanked along its western margin by a Neoproterozoic continental calc-alkaline magmatic arc coupled to a cryptic suture zone that can be traced for ~2400 km from Tibesti through western Darfur into Cameroon. We refer to this as the Central Saharan Belt. This, in a Gondwana framework, is part of a greater arc structure, which we here term the Great Central Gondwana Arc (GCGA). Inherited zircons and Nd isotopic ratios indicate the Neoproterozoic magmas in the central Sahara were predominantly derived from Mesoproterozoic continental lithosphere. Regional deformation between 613 to 623 Ma marks the onset of late alkaline granite magmatism that was widespread across a much larger area of North Africa until about 550 Ma. During this magmatism, the region was exhumed and eroded, leaving a regional peneplain on which early Palaeozoic (Lower-Middle Cambrian) siliciclastic sediments were subsequently deposited, as part of a thick and widespread cover that stretched across much of North Africa and the Arabian Peninsula. Detrital zircons in these cover sequences provide evidence that a substantial volume of detritus was derived from the central Sahara region, because these sequences include ‘Kibaran-age’ zircons (ca. 1000 Ma) for which a source terrain has hitherto been lacking. We propose that, in preference to calling the central Sahara a “ghost” or “meta” craton, it should be called the Central Sahara Shield.

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Chowdhury, Priyadarshi, and Sumit Chakraborty. "Slow Cooling at Higher Temperatures Recorded within High-PMafic Granulites from the Southern Granulite Terrain, India: Implications for the Presence and Style of Plate Tectonics near the Archean–Proterozoic Boundary." Journal of Petrology 60, no. 3 (January 25, 2019): 441–86. http://dx.doi.org/10.1093/petrology/egz001.

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44

Scandolara, Jaime E., Pedro S. E. Ribeiro, Antônio A. S. Frasca, Reinhardt A. Fuck, and Joseneusa B. Rodrigues. "Geochemistry and geochronology of mafic rocks from the Vespor suite in the Juruena arc, Roosevelt-Juruena terrain, Brazil: Implications for Proterozoic crustal growth and geodynamic setting of the SW Amazonian craton." Journal of South American Earth Sciences 53 (August 2014): 20–49. http://dx.doi.org/10.1016/j.jsames.2014.04.001.

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45

Serov, Pavel A., Tamara B. Bayanova, Ekaterina N. Steshenko, Evgeniy L. Kunakkuzin, and Elena S. Borisenko. "Metallogenic Setting and Evolution of the Pados-Tundra Cr-Bearing Ultramafic Complex, Kola Peninsula: Evidence from Sm–Nd and U–Pb Isotopes." Minerals 10, no. 2 (February 19, 2020): 186. http://dx.doi.org/10.3390/min10020186.

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The article presents new Sm–Nd and U–Pb geochronological data on rocks of the poorly studied Pados-Tundra Cr-bearing complex. It is part of the Notozero mafic–ultramafic complex (western Kola Peninsula) and occurs at the border of the Paleoproterozoic Lapland Granulite Belt and the Archean Belomorian composite terrain. The Pados-Tundra complex hosts two major zones, the Dunite and Orthopyroxenite Blocks. Dunites are associated with four levels of chromite mineralization. Isotope Sm–Nd studies of dunites, harzburgites, and orthopyroxenites from the central part of the complex have been carried out. The isochron Sm–Nd age on 11 whole-rock samples from a rhythmically layered series of the complex is 2485 ± 38 Ma; the mineral Sm–Nd isochron for harzburgites shows the age of 2475 ± 38 Ma. It corresponds with the time of large-scale rifting that originated in the Fennoscandian Shield. When the rhythmically layered series of the intrusion and its chromite mineralization were formed, hornblendite dykes intruded. The U–Pb and Sm–Nd research has estimated their age at ca. 2080 Ma, which is likely to correspond with the occurrence of the Lapland–Kola Ocean. According to isotope Sm–Nd dating on metamorphic minerals (rutile, amphibole), the age of postmetamorphic cooling of rocks in the complex to 650–600 °C is 1872 ± 76 Ma. The U–Pb age on rutile from a hornblendite dyke (1804 ± 10 Ma) indicates further cooling to 450–400 °C. The conducted research has determined the early Proterozoic age of rocks in the rhythmically layered series in the Pados-Tundra complex. It is close to the age of the Paleoproterozoic ore magmatic system in the Fennoscandian Shield that developed 2.53–2.40 Ga ago. Later episodes of alterations in rocks are directly related to main metamorphic episodes in the region at the turn of 1.9 Ga. Results of the current study expand the geography of the vast Paleoproterozoic East Scandinavian Large Igneous Province and can be applied for further studies of similar mafic–ultramafic complexes.

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Green, A. G., W. Weber, and Z. Hajnal. "Evolution of Proterozoic terrains beneath the Williston Basin." Geology 13, no. 9 (1985): 624. http://dx.doi.org/10.1130/0091-7613(1985)13<624:eoptbt>2.0.co;2.

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47

Martínez-García, Enrique. "Proterozoic-Lower Paleozoic terrane accretion and Variscan domains in the Iberian Massif (Spain and Portugal)." Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 157, no. 4 (December 1, 2006): 559–74. http://dx.doi.org/10.1127/1860-1804/2006/0157-0559.

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48

Kalsbeek, F. "Archaean and early Proterozoic basement provinces in Greenland." Rapport Grønlands Geologiske Undersøgelse 160 (January 1, 1994): 37–40. http://dx.doi.org/10.34194/rapggu.v160.8227.

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Information about the age and plate-tectonic setting of Precambrian basement terrains is of major importance for the evaluation of their mineral potential. The Geological Survey of Greenland (GGU) has therefore over the last two decades collected and published geochronological information on Greenland basement areas, based on whole rock Rb-Sr, Pb-Pb, Sm-Nd and zircon U-Pb isotope data. These isotope data, together with other geochemical information, also yield important clues for the plate-tectonic setting of the investigated terrains. GGU does not have laboratory facilities for isotope work, and most studies were therefore carried out in cooperation with university scientists from Denmark and abroad. This effort has led to the recognition of a number of distinct Precambrian basement provinces. A broad outline of results is given below.

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Hall, R. P., D. J. Hughes, and C. R. L. Friend. "Ti-rich plagioclase-phyric dykes of southern West Greenland." Rapport Grønlands Geologiske Undersøgelse 135 (December 31, 1987): 46–52. http://dx.doi.org/10.34194/rapggu.v135.7997.

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The investigation of Proterozoic basic dykes in southern West Greenland stemmed from the programme of systematic mapping of the Archaean craton in that region by the Geological Survey of Greenland (GGU). This work began in the southern Frederikshåb region in the early 1960s (Jensen, 1968, 1969) and progressed northwards, from bases in the Fiskenæsset (Kalsbeek & Myers, 1973; GGU, 1976), Godthåb (Allaart et al., 1977) and Sukkertoppen areas (Allaart et al., 1978). The results of most of this mapping work were summarized by Bridgwater et al. (1976) and compiled onto a 1:500 000 scale geological map sheet by Allaart (1982). The distribution of the major Proterozoic dykes which cut the entire region is shown on this map. While the basic dykes are individually minor intrusions, many are up to 50 metres wide and continuous for several tens of kilometres, and collectively they represent a major magmatic event. As many of the Archaean terrains of the world possess Proterozoic basic dyke swarms, their compositions are crucial to a correlation of events from one craton to another and to an understanding of crustal and mantle evolution after the world-wide late Archaean sialic crust-forming event.

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Lewry, J. F., K. D. Collerson, M. E. Bickford, and W. R. Van Schmus. "Comment and Reply on “Evolution of Proterozoic terrains beneath the Williston Basin”." Geology 14, no. 8 (1986): 715. http://dx.doi.org/10.1130/0091-7613(1986)14<715:caroeo>2.0.co;2.

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