Abstract
New magnetometric, petrological, and geochemical data on basalts from the central Romanche Fracture Zone (FZ) allow us to classify these rocks into two groups. The igneous rocks from the active part of the fracture zone that experienced transtension are referred to as alkaline rocks. According to some indications, they are younger that the oceanic tholeiites of the southern fault-line ridge, which were affected by elevated pressure in the past. These data indicate with a high probability that the Romanche FZ belongs to a rare group of magmatically active demarcation transform lines that separate large oceanic domains different in structural and geochemical features.
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Referencses
Yu. A. Bogdanov and V. V. Ploshko, “Igneous and Metamorphic Rocks in the Romanche Deepwater Basin,” Dokl. Akad. Nauk SSSR 177(4), 909–912 (1967).
E. Bonatti, “Origin of the Large Fracture Zones Offsetting the Mid-Atlantic Ridge,” Geotektonika 30(6), 5–16 (1996) [Geotectonics 30 (6), 430–440(1996)].
E. Bonatti, J. Honnorez, and G. Ferrara, “Peridotite-Gabbro-Basalt Complex in the Equatorial Mid-Atlantic Ridge,” in A Discussion on the Petrology of Igneous and Metamorphic Rocks from the Ocean Floor (The Royal Society, London, 1971; Mir, Moscow, 1973), pp. 9–29.
A. A. Bulychev, D. A. Gilod, K. V. Krivosheya, et al., “3D Modeling of the Tectonosphere in the Romanche Transform Zone (Equatorial Atlantic) from Gravimetric Data,” Vest. Mosk. Gos. Univ., Ser. Geol., No. 5, 74–80 (2005).
K. A. Valeev and V. I. Maksimochkin, “Thermal Remanent and Inductive Magnetization of Magnetite and Rocks at Quasiconfining Pressure,” Fiz. Zemli 24(2), 106–112 (1988).
D. A. Gilod, A. A. Bulychev, K. V. Krivosheya, et al., “Structure of the Romanche Fracture Zone (Equatorial Atlantic) from Gravimetric Data,” Vestn. Mosk. Gos. Univ., Ser. Geol., No. 4, 48–56 (2006).
G. L. Kashintsev, “Geodynamics and Magmatism at the Initial Stages of the Formation of the Atlantic Ocean,” Geotektonika 35(2), 64–77 (2001) [Geotectonics 35 (2), 134–145 (2001)].
A. A. Peive, “Structural and Compositional Heterogeneities, Magmatism, and Geodynamic Features of the Atlantic Ocean,” (Nauchnyi Mir, Moscow, 2002) [in Russian].
A. S. Perfil’ev, A. A. Peive, Yu. M. Pushcharovsky, et al., “The Romanche Fault Zone: Structure, Evolution, and Geodynamics,” Geotektonika 28(4), 3–14 (1994).
Yu. M. Pushcharovsky, “Demarcation Faults in Oceans As a Special Category of Tectonic Boundaries,” Dokl. Akad. Nauk 335(5), 616–620 (1994).
N. M. Sushchevskaya, A. A. Peive, S. G. Skolotnev, et al., “Nature of Rift Volcanism in the region of the Romanche-Chain Fracture Zones (Equatorial Atlantic),” Geokhimiya 32(2), 287–302 (1994).
N. M. Sushchevskaya and T. I. Tsekhonya, “Specific Features of Basaltic Magmatism in Equatorial Zone of the Mid-Atlantic Ridge,” Geokhimiya 32(5), 691–707 (1994).
N. M. Sushchevskaya, E. Bonatti, A. A. Peive, et al., “Heterogeneity of Rift Magmatism in the Equatorial Province of the Mid-Atlantic Ridge (15° N to 3° S),” Geokhimiya 40(1), 30–55 (2002) [Geochem. Int. 40 (1), 26–50 (2002)].
V. I. Trukhin, A. A. Shreider, V. A. Zhilyaeva, et al., “Seafloor Magnetism of the Romanche Transform Zone (Equatorial Atlantic),” Fiz. Zemli 41(3), 3–17 (2005) [Izv. Physics Solid Earth 41 (3), 179–192 (2005)].
Al. A. Shreider, A. A. Shreider, A. A. Bulychev, et al., “Transtension of the Romanche Transform Fault,” Okeanologiya 46(5), 726–734 (2006) [Oceanology 46 (5), 683–691 (2006)].
E. Bonatti, “Ultramafic Rocks from the Mid-Atlantic Ridge,” Nature 219(5152), 363–364 (1968).
E. Bonatti, “Subcontinental Mantle Exposed in the Atlantic Ocean on St. Paul Islet,” Nature 345(6378), 800–802 (1990).
E. Bonatti, “Anomalous Opening of the Equatorial Atlantic Due to an Equatorial Mantle Thermal Minimum,” Earth Planet. Sci. Lett. 143(1–2), 147–160 (1996).
E. Bonatti and J. Honnorez, “Section of the Earth’s Crust in the Equatorial Atlantic,” J. Geophys. Res. 81(23), 4104–4115 (1976).
E. Bonatti, M. Seyler, and N. Sushchevskaya, “A Cold Suboceanic Mantle Belt at the Earth’s Equator,” Science 261(5118), 315–320 (1993).
E. Bonatti, M. Ligi, L. Gasperini, et al., “Transform Migration and Vertical Tectonics at the Romanche Fracture Zone, Equatorial Atlantic,” J. Geophys. Res. 99(B11), 21779–21802 (1994).
E. Bonatti, D. Brunelli, M. Ligi, et al., “Steady State Creation of Crust Free Lithosphere at Cold Spots in Mid-Ocean Ridge,” Geology 29(11), 979–982 (2001).
Catalogue Earthquakes USGS, http://eqint.cr.usgs.gov/neic/cgi.
F. A. Frey, “Rare Earth and Potassium Abundances in St. Paul’s Rocks,” Earth Planet. Sci. Lett. 7(4), 351–360 (1970).
J. Honnorez and E. Bonatti, “Nepheline Gabbro from the Mid-Atlantic Ridge,” Nature 228(5374), 850–852 (1970).
M. Ligi, E. Bonatti, and A. N. Poliakov, “Oceanic Broad Multifault Transform Plate Boundaries,” Geology 30(1), 11–14 (2002).
W. G. Melson and T. O’Hearn, “Zero Age” Variations in the Composition of Abyssal Volcanic Rocks along the Axial Zone of the Mid-Atlantic Ridge,” in The Geology of North America (Am. Geol. Soc., 1986), pp. 117–135.
M. Prinz, K. Keil, J. A. Green, et al., “Ultramafic and Mafic Dredge Samples from Equatorial Mid-Atlantic Ridge and Fracture Zones,” J. Geophys. Res. 81(23), 4087–4103 (1976).
M. C. Roden, S. R. Hart, F. A. Frey, et al., “Sr, Nd and Pb Isotopic and REE Geochemistry of St. Paul’s Rocks: the Metamorphic and Metasomatic Development of an Alkali Basalt Mantle Source,” Contrib. Mineral. Petrol. 85(4), 376–390 (1984).
M. Seyler and E. Bonatti, “Regional-Scale Melt Rock Interaction in the Romanche Fracture Zone (Atlantic Ocean),” Earth Planet. Sci. Lett. 146(1–2), 273–287 (1997).
J. M. Sinton, “Ultramafic Inclusions and High-Pressure Xenocrysts in Submarine Basanitoid, Equatorial Mid-Atlantic Ridge,” Contrib. Mineral. Petrol. 70(1), 49–57 (1979).
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Original Russian Text © G.L. Kashintsev, A.A. Shreider, V.I. Maksimochkin, A.A. Bulychev, D.A. Gilod, 2008, published in Geotektonika, 2008, No. 4, pp. 85–92.
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Kashintsev, G.L., Shreider, A.A., Maksimochkin, V.I. et al. Transtension and alkaline magmatism of the Romanche Fracture Zone. Geotecton. 42, 318–323 (2008). https://doi.org/10.1134/S0016852108040055
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DOI: https://doi.org/10.1134/S0016852108040055