Abstract
Local U-Pb dating of zircons separated from various rocks in the crest zone of the Mid-Atlantic Ridge (MAR) and Carter Seamount (Sierra Leone Rise) is performed. Younger zircons formed in situ in combination with older xenogenic zircons are revealed in enriched basalts, alkaline volcanic rocks, gabbroic rocks, and plagiogranites. Only older zircons are found in depleted basalts and peridotites. Older zircons are ubiquitous in the young oceanic lithosphere of the Central Atlantic. The age of the younger zircons from the crest zone of the MAR ranges from 0.38 to 11.26 Ma and progressively increases receding from the axial zone of the ridge. This fact provides additional evidence for spreading of the oceanic floor. The rate of half-spreading calculated from the age of the studied zircons is close to the rate of half-spreading estimated from magnetic anomalies. The age of the younger zircons from Carter Seamount (58 Ma) corresponds to the age of the volcanic edifice. Older zircons make up an age series from 53 to 3200 Ma. Clusters of zircons differing in age reveal quasiperiodicity of about 200 Ma, which approximately corresponds to the global tectonic epochs in the geological evolution of the Earth. Several age groups of older zircons combine grains close in morphology and geochemistry: (1) Neoproterozoic and Phanerozoic (53–700 Ma) prismatic grains with slightly resorbed faces, well-preserved or translucent oscillatory zoning, and geochemical features inherent to magmatic zircons; (2) prismatic grains dated at 1811 Ma with resorbed faces and edges, fragmentary or translucent zoning, and geochemical features inherent to magmatic zircons; (3) ovoid and highly resorbed prismatic grains with chaotic internal structure and metamorphic geochemical parameters; the peak of their ages is 1880 Ma. The performed study indicates that older xenogenic zircons from young rocks in the crest zone of the MAR were captured by melt or incorporated into refractory restite probably in the sublithospheric mantle at the level of magma generation in the asthenosphere. It is suggested that zircons could have crystallized from the melts repeatedly migrating through the asthenosphere during geological history or were entrapped by the asthenosphere together with blocks of disintegrated and delaminated continental lithosphere in the process of breakup of the continents older than Gondwana. The variability in the age of older zircons even within individual samples may be regarded as evidence for active stirring of matter as a result of periodically arising and destroyed within-asthenospheric convective flows varying in orientation and scale.
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References
G. V. Agapova and V. N. Sharapov, “Morphostructure of the Eastern Junction of the Axial Rift of Mid-Atlantic Ridge (MAR) and the Cape Verde Fracture Zone,” Okeanologiya 33(2), 263–268 (1993).
V. E. Bel’tenev, V. N. Ivanov, S. G. Skolotnev, et al., “New Evidence for Sulfide Occurrences in the Markov Rift Deep at the Mid-Atlantic Ridge in the Equatorial Atlantic (6° N),” Dokl. Akad. Nauk 395(2), 215–220 (2004) [Dokl. Earth Sci. 395 (2), 187–191 (2004)].
B. V. BelyatskY, E. N. Lepekhina, A. V. Antonov, et al., “The Age and Origin of Gabbroic Rocks in MAR,” in Proceeding of XVII Intern. Sci. Conference (School) for Marine Geology: Geology of Seas and Oceans (GEOS, Moscow, 2007), Vol. IV, pp. 192–195 [in Russian].
B. V. Belyatsky, O. G. Shulyatin, E. N. Lepekhina, and S. A. Sergeev, “Polychronic Zircons from Gabbroids in the Mid-Atlantic Ridge,” in Proceedings of VI Working Meeting of the Russian Division of the International InteRidge Projects (VNIIOkeangeologiya, St. Petersburg, 2009), pp. 41–44 [in Russian].
N. A. Bozhko, “Precambrian Orogenic Belts: Typification and Position in Supercontinental Cycles,” in Proceedings of the 38th Tectonic Conference on Tectonics of the Earth’s Crust and Mantle and Tectonic Trends in Localization of Mineral Resources (GEOS, Moscow, 2005), Vol. 1, pp. 60–65 [in Russian].
N. A. Bozhko, “Supercontinental Cyclicity As Manifestation of Pulsatory Character of Global Tectonic Processes Against the Background of the Ordered Structural Grain of the Earth,” in Proceedings of the 41st Tectonic Conference on General and Regional Problems of Tectonics and Geodynamics (GEOS, Moscow, 2008), Vol. 1, pp. 102–105 [in Russian].
N. S. Bortnikov, G. N. Savel’eva, D. I. Matukov, et al., “The Zircon Age of Plagiogranites and Gabbros Based on SHRIMP Data: Pleistocene Intrusion in the MAR Rift Valley, 5°30.6′–5°32.4′ N,” Dokl. Akad. Nauk 404(1), 94–99 (2005) [Dokl. Earth Sci. 404 (7), 1054–1058 (2005)].
N. S. Bortnikov, E. V. Sharkov, O. A. Bogatikov, et al., “Finds of Young and Ancient Zircons in Gabbroids of the Markov Deep, Mid-Atlantic Ridge, 5°54′–5°02.2′ N (Results of SHRIMP-II U-Pb Dating): Implication for Deep Geodynamics of Modern Oceans,” Dokl. Akad. Nauk 421(2), 240–248 (2008) [Dokl. Earth Sci. 421 (5), 859–866 (2008)].
A. E. Eskin, “Characteristic Features of Ore Gabbro Formation in the Third Layer of the Oceanic Crust,” Dokl. Akad. Nauk 426(5), 644–648 (2009) [Dokl. Earth Sci. 427 (5), 711–714 (2009)].
P. K. Kepezhinskas, Yu. N. Raznitsin, A. O. Mazarovich, et al., “Composition of the Mantle and Magma Chambers in the Doldrums Fracture Zone, Central Atlantic,” in Magmatism and Tectonics of Oceans (Nauka, Moscow, 1990), pp. 122–143 [in Russian].
A. O. Mazarovich, “The Structure and History of the Volcanic Islands and Seamounts of the Tropical Atlantic,” Geotektonika 32(4), 53–65 (1998) [Geotectonics 32 (4), 296–307 (1998)].
A. M. Nikishin, “Geological History of the Earth,” in Proceedings of the 41st Tectonic Conference on General and Regional Problems of Tectonics and Geodynamics (GEOS, Moscow, 2008), Vol. 2, pp. 59–62 [in Russian].
V. A. Panaev and S. N. Mitulov, Seismostratigraphy of Sedimentary Cover of Atlantic Ocean (Nedra, Moscow, 1993) [in Russian].
A. A. Peive, Structural and Compositional Heterogeneities, Magmatism, and Geodynamic Features of Atlantic Ocean (Nauchnyi Mir, Moscow, 2002) [in Russian].
A. A. Peive, G. N. Savel’eva, S. G. Skolotnev, and V. A. Simonov, “Structure and Deformations of the Crust-Mantle Boundary Zone in the Vema Fracture Zone, Central Atlantic,” Geotektonika 35(1), 16–35 (2001) [Geotectonics 35 (1), 12–29 (2001)].
A. A. Peyve and S. G. Skolotnev, “Alkali Volcanism of the Bathymetrists Seamounts Chain (Central Atlantic): Description and Comparison,” Dokl. Akad. Nauk 425(1), 76–82 (2009) [Dokl. Earth Sci 425 (2), 243–248 (2009)].
A. S. Perfil’ev, Yu. N. Raznitsin, A. A. Peyve, et al., “MAR Rift Valley and Fifteen Twenty Fracture Zone Intersection: Magmatism and Structure,” Petrologiya 4(2), 183–199 (1996) [Petrology 4 (2), 168–183 (1996)].
V. V. Petrova, S. G. Skolotnev, and N. I. Chistyakova, Composition of Accessory Zircon from Tuffs of Carter Seamount (Sierra Leone Rise, East Atlantic), Dokl. Akad. Nauk 431(1), 67–71 (2010) [Dokl. Earth Sci. 431 (1), 275–279 (2010)].
Yu. M. Pushcharovskii, S. G. Skolotnev, A. A. Peive, et al., Geology and Metallogeny of the Mid-Atlantic Ridge 5–7°N (GEOS, Moscow, 2004) [in Russian].
Yu. N. Raznitsin, Tectonic Delamination of the Lithosphere in Young Oceans and Paleooceanic Basins (Nauka, Moscow, 2004) [in Russian].
G. N. Savel’eva, A. V. Sobolev, V. G. Batanova, et al., “Structure of Melt Flow Channels in the Mantle,” Geotektonika 42(6), 1–21 (2008) [Geotectonics 42 (6), 430–447 (2008)].
G. N. Savel’eva, P. V. Suslov, and A. N. Larionov, “Vendian Tectono-Magmatic Events in Mantle Ophiolitic Complexes of the Polar Urals: U-Pb Dating of Zircon from Chromitite,” Geotektonika 41(2), 23–33 (2007) [Geotectonics 41 (2), 105–113 (2007)].
S. G. Skolotnev, “Gabbroids of the Vema Fracture Zone: Textures, Composition, and Tectonic Setting,” Petrologiya 11(1), 18–31 (2003) [Petrology 11 (1), 31–47 (2003)].
S. G. Skolotnev, V. E. Bel’tenev, E. N. Lepekhina, and I. S. Ipat’eva, “Young and Old Zircons from Rocks of the Oceanic Lithosphere in Central Atlantic: Geotectonic Implications,” in Proceeding of XVIII Intern. Sci. Conference (School) for Marine Geology: Geology of Seas and Oceans (GEOS, Moscow, 2009), Vol. V, pp. 251–255 [in Russian].
S. G. Skolotnev, E. N. Lepekhina, and I. S. Ipat’eva, “Age of Zircons from Igneous Rocks of the Markov Basin (Axial Zone of the MAR, 5–6° N) and Interaction of Tectonic Magmatic, and Hydrothermal Processes,” in Proceedings of VI Working Meeting of the Russian Division of the International InteRidge Projects (VNIIOkeangeologiya, St. Petersburg, 2009), pp. 30–33 [in Russian].
S. G. Skolotnev, A. A. Peyve, N. S. Bortnikov, et al., “Geology of Ore-Hosting Rift Deeps near the Sierra Fracture Zone, Equatorial Atlantic,” Dokl. Akad. Nauk 391(2), 232–238 (2003) [Dokl. Earth Sci. 391 (5), 679–684 (2003)].
S. G. Skolotnev, A. A. Peyve, V. Yu. Lavrushin, et al., “Geological Structure and Indicators of Hydrothermal Ore-Bearing Activity at the Junction of the Southern Rift Segment and the Doldrums Transform Fracture Zone, Central Atlantic,” Dokl. Akad. Nauk 407(3), 372–377 (2006) [Dokl. Earth Sci. 407A (3), 361–365 (2006)].
S. G. Skolotnev, A. A. Peyve, and S. M. Lyapunov, “Tectono-Volcanic Activity at the Axial Zone of the Mid-Atlantic Ridge between the Fifteen Twenty and Mercurius Fracture Zones, Central Atlantic,” Petrologiya 7(6), 591–610 (1999) [Petrology 7 (6), 556–573 (1999)].
S. G. Skolotnev, A. A. Peyve, V. A. Simonov, et al., “Volcanism of Mid-Atlantic Ridge in the Area of Sierra Leone Fracture Zone, Central Atlantic,” Russ. J. Earth Sci. (electronic version, www.agu.org/wrs/rjes) 5(2) (2003).
S. G. Skolotnev, N. N. Turko, S. Yu. Sokolov, et al., “New Data on the Geological Structure of the Junction of the Cape Verde Plateau, Cape Verde Abyssal Plain, and Bathymetrists Seamounts (Central Atlantic Ocean) 416(4), 1037–1041 (2007) [Dokl. Earth Sci. 416 (7), 1037–1041 (2007)].
S. G. Skolotnev, N. V. Tsukanov, N. N. Turko, and A. A. Peyve, “New Data on Neotectonic Activity in the Crest Zone of the Mid-Atlantic Ridge at 5–6° N,” Dokl. Akad. Nauk 395(1), 89–90 (2004) [Dokl Earth Sci. 395 (2), 178–182 (2004)].
A. V. Sobolev, L. V. Dmitriev, O. P. Tsameryan, et al., “Structure and Origin of Geochemical Anomaly in Basalts of Mid-Atlantic Ridge between 12–18° N,” Dokl. Akad. Nauk SSSR 326(3), 541–546 (1992).
Structure of the Doldrums Fracture Zone, Central Atlantic, Ed. by Yu. M. Pushcharovsky (Nauka, Moscow, 1991) [in Russian].
Structure of the Fifteen Twenty Fracture Zone, Central Atlantic, Ed. by Yu. M. Pushcharovsky (Nauka, Moscow, 1989) [in Russian].
V. E. Khain, Main Problems of Modern Geology (Nauka, Moscow, 1995) [in Russian].
V. E. Khain, Tectonics of Continents and Oceans (Nauchnyi Mir, Moscow, 2001) [in Russian].
V. E. Khain, “Tectonics and Dynamics of the Earth,” in Tectonics and Geodynamics (VSEGEI, St. Petersburg, 2004), pp. 33–41 [in Russian].
V. E. Khain and M. G. Lomize, Geotectonics with Principles of Geodynamics (Moscow State Univ., Moscow, 1995) [in Russian].
O. G. Shulyatin, S. I. Andreev, B. V. Belyatsky, and A. I. Trukhalev, “Structural and Tectonic Position and Age of Plutonic Mafic-Ultramafic Complexes of MAR,” in Sixty Years in Arctica, Antarctica, and World Ocean (VNIIOkeangeologiya, St. Petersburg, 2008), pp. 392–408 [in Russian].
J. M. Auzende, D. Bideau, E. Bonatti, et al., “Direct Observation of a Section Through Slow-Spreading Oceanic Crust,” Nature 337, 726–729 (1989).
S. L. Baldwin and T. R. Ireland, “A Tale of Two Eras: Plio-Pleistocene Unroofing of Cenozoic and Late Archean Zircons from Active Metamorphic Core Complexes, Solomon Sea, Papua New Guinea,” Geology 23, 1023–1026 (1995).
L. P. Black and S. L. Kamo, “TEMORA 1: A New Zircon Standard for U-Pb Geochronology,” Chem. Geol. 200, 155–170 (2003).
E. Bonatti, “Subcontinental Mantle Exposed in the Atlantic Ocean on the St. Peter-Paul Islets,” Nature 345, 800–802 (1990).
E. Bonatti and K. Crane, “Oscillatory Spreading Explanation of Anomalously Old Uplifted Crust Near Oceanic Transforms,” Nature 300, 343–345 (1982).
E. Bonatti, M. Ligi, A. Borsetti, et al., “Lower Cretaceous Deposits Trapped Near the Equatorial Mid-Atlantic Ridge,” Nature 380, 518–520 (1996).
E. Bonatti, M. Ligi, D. Brunelli, et al., “Mantle Thermal Pulses Below the Mid-Atlantic Ridge and Temporal Variations in the Formation of Oceanic Lithosphere,” Nature 423, 499–505 (2003).
E. Bonatti, M. Ligi, L. Gasperini, et al., “Imaging Crustal Uplift, Emersion and Subsidence at the Vema Fracture Zone,” EOS, No. 9, 371–372 (1994).
E. Bonatti, M. Ligi, L. Gasperini, et al., “Transform Migration and Vertical Tectonics at the Romanche Fracture Zone, Equatorial Atlantic,” J. Geophys. Res. 99 (1994).
E. Bonatti, A. Peyve, P. Kepezhinskas, et al., “Upper Mantle Heterogeneity below the MAR (0–15° N),” J. Geophys. Res. 97(B4), 4461–4476 (1992).
S. C. Cande, J. L. LaBrecque, and W. F. Haxby, “Plate Kinematics of the South Atlantic: Chron 34 to Present,” J. Geophys. Res. 93(B11), 13 479–13 492 (1988).
M. Cannat, V. Mamaloukas-Frangooulis, J. M. Auzende, et al., “A Geological Cross Section of the Vema Fracture Zone Transversive Ridge, Atlantic Ocean,” J. Geodynamics 13(2/4), 97–118 (1991).
M. Cannat, Y. Lagabrielle, H. Bougault, et al., “Ultramafic and Gabbroic Exposures at the Mid-Atlantic Ridge: Geological Mapping in the 15° N Region,” Tectonophysics 279, 193–213 (1997).
F. Corfu, J. M. Hanchar, P. W. O. Hoskin, and P. Kinny, “Atlas of Zircon Textures,” Rev. Mineral. Geochem. 53, 468–500 (2003).
L. Dosso, H. Bougault, and J.-L. Joron, “Geochemical Morphology of the North Mid-Atlantic Ridge, 10–24° N: Trace Element-Isotope Complementarity,” Earth Planet. Sci. Lett. 120, 443–462 (1993).
L. Dosso, B. B. Hanan, H. Bougault, et al., “Sr-Nd-Pb Geochemical Morphology Between 10 and 17° N on Mid-Atlantic Ridge: a New MORB Isotope Signature,” Earth Planet. Sci. Lett. 106(1), 29–43 (1991).
R. Doucelance, S. Escrig, M. Moreira, et al., “Pb-Sr-He and Trace Element Geochemistry of the Cape Verde Archipelago,” Geochim. Cosmochim. Acta 67(19), 3717–3733 (2003).
F. A. Frey, D. Weiss, Y. A. Borisova, and G. Xu, “Involvement of Continental Crust in the Formation of the Cretaceous Kerguelen Plateau: New Perspectives from ODP Leg 120 Sites,” J. Petrol. 43, 1207–1239.
General Bathymetric Chart of the Ocean (GEBCO) 1: 10000000 (Canad. Hydrograph. Serv., Ottawa, 1982).
S. A. Gibson, R. N. Thompson, J. A. Day, et al., “Melt Generation Processes Associated with the Tristan Mantle Plume: Constraints of the Origin of EM-1,” Earth Planet. Sci. Lett. 237, 744–767 (2005).
A. W. Hoffman, “Chemical Differentiation of the Earth: The Relationships Between Mantle, Continental Crust, and Oceanic Crust,” Earth Planet. Sci. Lett. 90, 297–314 (1991).
J. Honnorez, C. Mevel, and R. Montigny, “Geotectonic Significance of Gneissic Amphibolites from the Vema Fracture Zone, Equatorial Mid-Atlantic Ridge,” J. Geophys. Res. 89(B9), 11 379–11 400 (1984).
P. W. O. Hoskin and U. Schaltegger, “The Composition of Zircon and Igneous and Metamorphic Petrogenesis,” Rev. Mineral. Geochem. 53, 27–62 (2003).
P. B. Kelemen, N. Shimizu, and V. J. M. Salters, “Extraction of Mid-Ocean-Ridge Basalt from the Upwelling Mantle by Focused Flow of Melt in Dunite Channels,” Nature 375, 747–753 (1995).
E. M. Klein and Ch. H. Langmuir, “Global Correlations of Ocean Ridge Basalt Chemistry with Axial Depth and Crustal Thickness,” J. Geophys. Res. 92(B8), 8089–8115 (1987).
K. Klitgord and H. Schouten, “Plate Kinematics of the Central Atlantic,” in The Geology of North America: the Western Atlantic Region (DNAG Ser., Vol. 1, 1978), pp. 351–377.
Leg 209. Preliminary Report. Drilling Mantle Peridotite along the Mid-Atlantic Ridge from 14 to 16° N (www-ODP.Taamu.edu, 2003).
K. R. Ludwig, SQUID 1.00 Users Manual (Berkeley Geochronology Center, Berkeley, 2000), Spec. Publ. no. 2.
P. J. Michael and E. Bonatti, “Peridotite Composition from the North Atlantic: Regional and Tectonic Variations and Implications for Partial Melting,” Earth Planet. Sci. Lett. 73, 91–104 (1985).
J. Ph. Morgan and W. J. Morgan, “Two-Stage Melting and Geochemical Evolution of the Mantle: a Recipe for Mantle Plume-Pudding,” Earth Planet. Sci. Lett. 170, 215–239 (1999).
A. Nicolas, “A Melt Extraction Based on Structural Studies in the Mantle Peridotites,” J. Petrol. 27, 999–1022 (1986).
Ya. Niu, Ch. H. Langmuir, and R. J. Kinzler, “The Origin of Abyssal Peridotites: a New Perspective,” Earth Planet. Sci. Lett. 152, 251–265 (1997).
A. Peyve, E. Bonatti, D. Brunelli, et al., “New Date on Some MAR Structures: Preliminary Results of R/V Akademik Nikolaj Strakhov 22 Cruise,” InterRidge News 9(2), 28 (2000).
J. Pilot, C. D. Werner, F. Haubrich, and N. Baumann, “Paleozoic and Proterozoic Zircons from the Mid-Atlantic Ridge,” Nature 393, 676–679 (1998).
M. Rabinowicz, A. Nicolas, and J. L. Vigneresse, “A Rolling Mill Effect in Asthenosphere Beneath Oceanic Spreading Centers,” Earth Planet. Sci. Lett. 67, 97–108 (1984).
W. R. Roest and B. J. Collete, “The Fifteen-Twenty Fracture Zone and North American-South American Plate Boundary,” J. Geol. Soc. 143(5), 833–843 (1986).
S. Rouzo, M. Rabinowicz, and A. Briais, “Segmentation of Mid-Ocean Ridges with An Axial Valley Induced by Small Mantle Convection,” Nature 374, 795–798 (1995).
D. T. Sandwell and W. H. V. Smith, “Marine Gravity Anomaly from Geosat and ERS 1 Satellite Altimetry,” J. Geoph. Res. 102, 10 039–10 054 (1997).
J. Schilling, B. Hanan, B. McCulli, et al., “Influence of the Sierra Leone Mantle Plume on the Equatorial Mid-Atlantic Ridge: A Nd-Sr-Pb Isotopic Study,” J. Geophys. Res. 99(B6), 12 005–12 028 (1994).
J. S. Stacey and J. D. Kramers, “Approximation of Terrestrial Lead Isotope Evolution by a Two-Stage Model,” Earth Planet. Sci. Lett. 26, 207–221 (1975).
F. Terra and J. A. Wasserburg, “U-Pb Method of the Isotopic Dating of the Minerals,” Earth Planet. Sci. Lett. 17, 36–51 (1972).
M. Wiedenbeck, P. Alle, F. Corfu, et al., “Three Natural Zircon Standards for U-Th-Pb, Lu-Hf, trace element, and REE analysis,” Geostandard Newsletter 19, 1–3 (1995).
I. S. Williams, “Applications of Microanalytical Techniques to Understanding Mineralizing Processes,” Rev. Econ. Geol. 7, 1–35 (1998).
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Original Russian Text © S.G. Skolotnev, V.E. Bel’tenev, E.N. Lepekhina, I.S. Ipat’eva, 2010, published in Geotektonika, 2010, Vol. 44, No. 6, pp. 24–59.
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Skolotnev, S.G., Bel’tenev, V.E., Lepekhina, E.N. et al. Younger and older zircons from rocks of the oceanic lithosphere in the Central Atlantic and their geotectonic implications. Geotecton. 44, 462–492 (2010). https://doi.org/10.1134/S0016852110060038
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DOI: https://doi.org/10.1134/S0016852110060038