Rift tectonic setting

Several different hypotheses on the tectonic setting of the Kuroko mine area have been proposed. They include volcanic front of island arc (T. Sato, 1974 Horikoshi, 1975a), rifting of island arc (Cathles, 1983a), back-arc depression (Fujioka, 1983 Uyeda, 1983), and back-arc basin. 

Tectonic setting Back-arc rift or continental rift Sediment-barren midoceanic Sediment-covered... 

Faleide, J.I., VSgnes, E. and Gudlaugsson, S.T. 1993. Late Mesozoic -Cenozoic evolution of the south-western Barents Sea in a regional rift-shear tectonic setting. Mar. Pet. Geol. 10 186-214. 

In each of the three tectonic settings discussed above - convergent margins, within-plate (oceanic and continental crust) and at rifted margins - the dominant flux from the mantle to the continental crust is basaltic. This however poses a major problem, for the continental crust is not basaltic in composition, rather, as will be shown below (Table 4.2), the average bulk composition of the continental crust is andesitic. This paradox is one of the... 

Chapin, C.E. Cather, S.M. (1994) Tectonic setting of the axial basins of the northern and central Rio Grande rift. In Basins of the Rio Grande Rift Structure, Stratigraphy, and Tectonic Setting (Eds Keller, G.R. Cather, S.M.), Geol. Soc. Am. Spec. Paper, 291, 5-25. 

Sedimentation during the Triassic and Jurassic in the Gulf of Mexico Basin was controlled primarily by rift margin tectonics (Mancini et a/. 1985, 1990 Salvador 1987). The regional tectonic setting was... 

Initial heat flow, Q, is estimated from the present-day values of surface heat flow in the regions with tectonic settings similar to that expected for the time of the basin initiation. For example, Q s 100-110 mW m" is typical of continental rift areas (Baikal Lake, African rift system) however, on rift shoulders, Q can be nearly 65-85 mW (Smirnov 1980). Estimations of the initial heat flow can be adjusted by analysis of variations in tectonic subsidence of the basement (see following sections). In the case of the Oued el-Mya Basin, Q is approximately 52 mW m" (Fig. 6.5). 

The abrupt changes in depositional environments, styles and tectonic setting of Middle and Late Proterozoic rocks and their associated uranium deposits are significant evidence of extensive changes in supracrustal processes. Calc-alkaline volcanic and ophiolitic oceanic crustal suites are lacking in strata of this age. " Rock sequences are dominated by shallow marine to fluvial arenaceous clastic and carbonate sedimentary strata, and subaerial tholeiitic basalt and related shallow intrusions, all deposited in passively subsiding, rift-controlled basins. Oro-... 

The rocks of the TCZ are interpreted to have erupted in a transtensional continental rifting environment in the Late Siiurian to Middle Devonian. In this tectonic environment A-type granites are expected, and indeed the reiativeiy high Zr, Nb, and Y content in these rocks support this. However, many other geochemicai aspects of these rocks, i.e., high Ba, Rb, Th and K, are more typical of the I-type magmas that commonly occur in collisional settings. 

In this study gentiy seaward-dipping prograding successions of beachrock have been compared for three different geographic settings (1) an island in the southern Caribbean offshore from the mainland of Venezuela, part of the Caribbean Plate, (2) the north shore of Puerto Rico, and (3) the shoreline of the rift valley of the Gulf of Aqaba, a steep-sided tectonic valley that forms the northem segment of the Red Sea. 

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