[PDF] Top 20 Directory UMM :Data Elmu:jurnal:P:Precambrian Research:Vol101.Issue2-4.2000:

... Avalanches are characterized as large dislodged rock mass flows which move rapidly ( : 10 – 100 m/s) down generally high slopes (10°+ ). Cas and Wright (1987), p. 302) view an avalanche as ‘‘... a mobile, fluidal, ... Lihat dokumen lengkap

... (Pretorius, 1976) that extends for about 750 km along a north-east axis from Sodium in the Brit- stown District of the Northern Cape Province to Derdepoort in the Northwestern Province with a width of 350 km at its ... Lihat dokumen lengkap

... activity, phase 4 volcanism of transitional affinity caused endogenous dome formation and dike in- trusion in the central cauldron (Fig. 22d) and phase 2 endogenous lavas developed in the west- ern vent. A period ... Lihat dokumen lengkap

... Shallow water sedimentary units are generally considered scarce in Archean greenstone belts. We describe an unusual quartz arenite-subaerial andesite association within the Archean Hisovaara greenstone belt, a fragment ... Lihat dokumen lengkap

... in Precambrian Research represents a direct outgrowth of a special session ‘‘Processes in physical volcanology and volcani- clastic sedimentation: modern and ancient’’ at the meeting of the Geological (GAC) ... Lihat dokumen lengkap

... Fig. 4. Schematic model (left) of a subaqueous fire-fountain eruption (after Mueller and White, 1992). (A) Erupting fluid magma is torn apart by magmatic gas expansion in the fountain, is largely enclosed within a ... Lihat dokumen lengkap

... The basaltic tuff-lapilli tuff facies (TL) is less abundant than the LTB facies. TL beds are less than a few meters thick, and are composed of lapilli- and tuff-sized deposits with poorly defined upward thinning and ... Lihat dokumen lengkap

... the Precambrian, torrential rainfall due to disturbances of the weather patterns from volcanic eruptions would easily have reworked volcaniclastic debris in the Hekpoort palaeoenvi- ronment; under such conditions, ... Lihat dokumen lengkap

... (Eakins, 1972; Mueller et al., 1997; N’dah, 1998). The mafic flow component increases towards the SRG, displaying on-lapping (Eakins, 1972) and interstratification relationship between groups which is common to volcanic ... Lihat dokumen lengkap

... placed ejecta (Fig. 8h, j, k). Considering the sub- aqueous setting of the deposits, few possibilities accommodate ballistic or gas-driven transport with submarine sediment gravity flows. They in- clude: (1) a steam ... Lihat dokumen lengkap

... Two sparsely plagioclase-phyric rhyolite domes, 50 – 100 m thick and 125 – 250 m long as observed in 2-dimensional, vertically dipping exposures, are partly mantled by a rhyolite volcaniclastic complex that, on the south ... Lihat dokumen lengkap

... Archean volcanic rocks in the mafic-dominated, ca. 2.66 – 2.69 Ga Point Lake and Beaulieu River belts, Slave Province, Northwest Territories, are significant in demonstrating the facies that characterize specific ... Lihat dokumen lengkap

... There are two extreme viewpoints regarding the development of the continental crust throughout the history of the Earth. The first is that its volume grew by incremental extraction from the mantle, with return flux ... Lihat dokumen lengkap

... Whether or not coarse detrital sedimentary rocks occur within the \ 3.7 Ga Isua Greenstone Belt (IGB), southern west Greenland, has been debated for some time. Repeated, regional metamorphic, deformational, and ... Lihat dokumen lengkap

... David and I were involved in early collabora- tion of GGU with the Geological Survey of Canada (GSC), and in 1969 within Fred Tay- lor’s Torngat Mountain project we were put down with a zodiac and tent by a Cesna ... Lihat dokumen lengkap

... To the Southeast, the Aasivik terrane is in tectonic contact with a late Archaean complex of granitic and metapelitic gneisses with apparently randomly distributed mafic and ultramafic u[r] ... Lihat dokumen lengkap

... Nutman (1986) defined two stratigraphic se- quences (A and B). Sequence A formed ‘a coher- ent stratigraphy…along the whole length of the Isua supracrustal belt’ whereas part of sequence B was cut out by a fault (Nutman, ... Lihat dokumen lengkap

... palaeomagnetic data, that Neoproterozoic glaciations did not occur below 25° ...palaeomagnetic data indicate that the formation of Neoproterozoic ironstones and associated glacial sediments oc- curred in ... Lihat dokumen lengkap

... which trends north-south and is 500 km long and 40 km wide (Feybesse et al., 1990; Lompo et al., 1991). The Boromo greenstone belt is 2.15 – 2.10 Ga old (Feybesse and Milesi, 1994) and belongs to the Paleoproterozoic ... Lihat dokumen lengkap

... The data outlined below also argue against ensialic rifting of a stable Ar- chaean craton, and are consistent with a post-col- lisional setting for the felsic ...zircon data and whole- rock geochemical ... Lihat dokumen lengkap