 | | Journal (article/letter/editorial) | | Hydrothermally Altered Basalts from the Vema Fracture Zone (Mid-Atlantic Ridge) Catherine Mevel Laboratoire...Petrography dredged in the Vema fracture zone, Atlantic ocean, and contain prehnite + pumpellyite + epidote...white mica. The prehnite - pumpellyite association in these rocks differs from the prehnite - e p i d o t...association for most of the prehnite - pumpellyite facies metabasalts from the ocean crust described previously...active part of the Vema fracture zone, which offsets the crest of the mid-Atlantic Ridge by more than |  | | Journal (article/letter/editorial) | | compositional variations overlap with those of prehnite-pumpellyite facies rocks dredged from other oceanic...mineral in altered rocks dredged or drilled from ocean-floor that was originally produced by oceanic ridge...occurrences of pumpellyite have been reported from the ocean-floor, namely the median valley at 22~ latitude... the Vema fracture zone (Mevel, 1981) of the Mid-Atlantic Ridge, and the Garrett fracture zone of the...ophiolite (Ewarts and Schiffman, 1983) and from prehnite-pumpellyite facies rocks drilled 9 1999 The Mineralogical |  | | Journal (article/letter/editorial) | | Petrology of Rodingites from the Equatorial Mid-Atlantic Fracture Zones and Their Geotectonic Significance Jos6...Rodingites were dredged from fracture zones of the equatorial Mid-Atlantic Ridge along with serpentinized...positions along lines of weakness expressed as fracture zones. Introduction Sixteen different metagabbronorite...eight locations in the Vema and Romanehe Fracture Zones of the equatorial Mid-Atlantic Ridge show varying...dunite and containing diallage, grossularite, prehnite and/or serpentine. Rodingites have been reported |  | | Report (chapter) | | gneissic amphibolites in the Vema fracture zone, equatorial Mid-Atlantic Ridge J. Honnorez, C. M~vel &...metamorphosed gabbros and serpentinites in the Vema fracture zone during two separate cruises. Petrological...amphibotites were formed in a large subvertical shear zone related to transform fault movement which favoured...deformed metagabbros recrystailized away from the fault zone under static conditions from interaction with evolved...serpentinites during two separate cruises on the Vema fracture zone. These b a n d e d rocks, displaying alternating |  | SHIBUYA, T., KITAJIMA, K., KOMIYA, T., TERABAYASHI, M., MARUYAMA, S. (2007) Middle Archean ocean ridge hydrothermal metamorphism and alteration recorded in the Cleaverville area, Pilbara Craton, Western Australia. Journal of Metamorphic Geology, 25 (7) 751-767 doi:10.1111/j.1525-1314.2007.00725.x | Journal (article/letter/editorial) | | doi:10.1111/j.1525-1314.2007.00725.x Middle Archean ocean ridge hydrothermal metamorphism and alteration recorded...sub-greenschist facies (zones A and B) to greenschist facies (zone C) under low-pressure conditions. The boundaries...correspond to the thermal structure of ocean-floor metamorphism, at a mid-ocean ridge.The uppermost greenstone...important role in fixation of CO2 than present-day ocean-ridge hydrothermal alteration, as an interaction...greenstone; high XCO2; low-pressure metamorphism; ocean-floor metamorphism. INTRODUCTION Since the discovery |  | | Report (chapter) | | rocks from oceanic crust (mainly from the Indian Ocean) and ophiolitic terranes (principally the Semail...by dredging the steep scarps of cross-cutting fracture systems. Such tectonically active regions may...some occurrences the crustal section exposed in fracture zones may also be much thinner than intact crust...associated silicic differentiates--from the m o d e r n ocean basins. Such data are sparse because of limited...from large fracture zones, taken as marking transform faults that cross-cut the Indian Ocean Ridge System |  | | Journal (article/letter/editorial) | | isotope compositions. The pervasive zeolite and prehnite-pumpellyite facies mineral assemblages found in...its origin near an island arc rather than deep ocean spreading center. 1. Introduction In the past few...ophiolites with those observed in ocean crust formed at deep ocean spreading centers. However, the igneous...Puerto remnant compatible with its origin in a small ocean basin (possibly near-arc) as opposed to a mid-oceanic...Hyl~lbyual IhIrusIOhS I-it ) . I i PUMPELLYITE i ZONE i tllu~t HI~ GaOlx) ----i Vorioble a Sl=oradi¢ |  | Sharkov, E. V., Abramov, S. S., Simonov, V. A., Krinov, D. I., Skolotnev, S. G., Bel’tenev, V. E., Bortnikov, N. S. (2007) Hydrothermal alteration and sulfide mineralization in gabbroids of the Markov Deep (Mid-Atlantic Ridge, 6° N) Geology of Ore Deposits, 49 (6) 467-486 doi:10.1134/s1075701507060037 | Journal (article/letter/editorial) | | Mineralization in Gabbroids of the Markov Deep (Mid-Atlantic Ridge, 6° N) E. V. Sharkova, S. S. Abramova, V...site situated in the axial rift valley of the Mid-Atlantic Ridge (Markov Deep, 6° N). Two associations of...subvolcanic, and volcanic rocks were dredged: (1) mid-ocean ridge basalts (MORB) and their intrusive analogues...and depleted in Ni and Cr. The main ore-bearing zone is situated at the foot of the eastern wall of the...altered rocks is composed of quartz–sulfide and prehnite–sulfide veinlets, disseminated sulfide, and veined |  | Talbi, EL H., Honnorez, J., Clauer, N., Gauthier-Lafaye, F., Stille, P. (1999) Petrology, isotope geochemistry and chemical budgets of oceanic gabbros-seawater interactions in the Equatorial Atlantic. Contributions to Mineralogy and Petrology, 137 (3) 246-266 doi:10.1007/s004100050549 | Journal (article/letter/editorial) | | gabbros-seawater interactions in the Equatorial Atlantic Received: 8 March 1999 / Accepted: 12 July 1999...presented for metagabbros from the Romanche and Vema fracture zones. These rocks were aected by several types...plagioclase epidote titanite chlorite prehnite). Hydrothermal alteration of these gabbroic rocks...gabbros contributes to the control of the global ocean geochemistry. EL H. Talbi (&)1 á J. Honnorez á...that the major chemical composition of the world ocean has been quite constant (e.g., Thompson 1983; Brown |  | | Journal (article/letter/editorial) | | metamorphic conditions, which include zeolite, prehnite-pumpellyite, pumpellyite-actinolite, lawsonite-albite...environment. It is a diagnostic mineral for both prehnite-pumpellyite facies (Coombs et al. 1970) and p...rack; 7 meta-graywacke; Z zeolite facies; P P prehnite-pumpellyite facies; L A lawsonite-albite facies;...hydrothermal alteration of oceanic basalts from the Vema fracture zone has been suggested to have formed at about...highpressure. It is typically associated with prehnite, albite, chlorite, and epidote in Northern Apennines |  | | Journal (article/letter/editorial) | | grade of metamorphism was predominantly within the prehnite-pumpellyite facics, although greenschist facies...Caledonides have been metamorphosed within the prehnite-pumpellyite facies and lower part of the greenschist...the more pelitic rocks, and by a non-penetrative fracture-type cleavage in the more competent psammitic...composition. These assemblages include laumontite, prehnite, pumpellyite, and, at slightly higher grades,...have enabled the identification of the zeolite, prehnite-pumpellyite, pumpellyite-actinolite, and greenschist |  | | Journal (article/letter/editorial) | | recrystallization under widely diverse P-T conditions. Prehnite-pumpellyite and greenschist facies assemblages...while to the east the ophiolite is bordered by prehnite-pumpellyite facies rocks of the Rai Sandstone...quartz and hematite. Calcite is present as central fracture fillings and small veinlets cross-cutting pumpellyite...The Patuki metasediments have suffered the same prehnite-pumpellyite grade metamorphism as the spilites...spilites. Authigenic minerals include chlorite, prehnite, pumpellyite, sericite and calcite. Secondary quartz |  | | Journal (article/letter/editorial) | | are compatible with an origin as ocean floor, both the normal mid-ocean-ridge-basalt and the enriched-within-plate...comparable to the biotite and perhaps the garnet zone of pelitic rocks of the greenschist and amphibolite...Caribbean (Montgomery et al., 1994a, 1994b). The ocean floor on which these cherts were deposited may be...addition to the occurrence of veins with epidote or prehnite—indicates retrograde metamorphism to greenschist...places, bytownite is replaced by intergrowths of prehnite and andesine. Opaque minerals present are anhedral |  | | Journal (article/letter/editorial) | | presented. Comparison with metagabbros dredged from the ocean floor shows that synkinematic amphibolite facies...gabbroic layer near the axis of a slowly spreading ocean ridge before the intrusion of diabase dykes. This...most of the other ophiolitic gabbros of the Piemont zone prior to the low-temperature/high-pressure Alpine...amphibolite facies, have been dredged from the ocean floor in many places. Some o f these rocks are typical...Alpine recrystallization characterized by albite, prehnite, pumpellyite, actinolite, epidote [4,5,9]. Very |  | | Journal (article/letter/editorial) | | metabasites of the Horokanai ophiolite in the Kamuikotan zone, Hokkaido, Japan Hideo Ishizuka Department of Geology...o k a n a i ophiolite in the K a m u i k o t a n zone, Hokkaido, Japan, filling veins or amygdules, replacing...the Horokanai ophiolite occurs in the Kamuikotan zone, Hokkaido, Japan (Fig. 1A), emplaced tectonically...in low-grade metamorphic rocks of the zeolite, prehnite-pumpellyite, pumpellyite-actinolite and blueschist...metabasites of the Horokanai ophiolite in the Kamuikotan zone, Hokkaido, Japan. Such compositional features appear |  | | Report (chapter) | | Gabbros exposed at Hess Deep and sampled by the Ocean Drilling Program during Leg 147 provide the first...during rapid, buoyant rise and discharge at the ocean floor (e.g. Lowell 1975; Strens & Cann 1982, 1986;...Hydrothermaland 185 Biological Segmentation of Mid-Ocean Ridges, Geological Society Special Publication No...1994); consequently, greater tectonically induced fracture permeability and hence access of seawater to the...across a significant proportion of fast-spread ocean floor, and segmentation may play an important role |  | Oliver, G. J. H., Smellie, J. L., Thomas, L. J., Casey, D. M., Kemp, A. E. S., Evans, L. J., Baldwin, J. R., Hepworth, B.C. (1984) Early Palaeozoic metamorphic history of the Midland Valley, Southern Uplands–Longford-Down massif and the Lake District, British Isles. Transactions of the Royal Society of Edinburgh: Earth Sciences, 75 (2) 245-258 doi:10.1017/s0263593300013882 | Journal (article/letter/editorial) | | remnants of (?)pre-Arenig ocean-floor subducted during closure of the Iapetus Ocean. In the early Ordovician...newly-formed ocean crust. The obduction process piled up a thick sequence of various ocean-floor types...reached pumpellyite-actinolite facies; elsewhere prehnite-pumpellyite and zeolite facies was attained. Whilst...Accretion, tectonic burial and metamorphism of ocean-floor and trench sediment was continuous in the...Ordovician history of burial metamorphism up to prehnite-pumpellyite facies. The Late Ordovician and Silurian |  | | Journal (article/letter/editorial) | | surrounded by other plagioclases in which little or no prehnite has developed. There is no epitaxial growth of...develop within or upon the same primary phases. Prehnite, pumpellyite and epidote are all formed within...with a radiating habit and across these crystals prehnite, pumpellyite and/or epidote grow. Texturally these...growth of low temperature minerals - chlorite, prehnite, pumpellyite, epidote and newly developed pure...These minerals are chlorite, albite, epidote, prehnite and pumpellyite. No amphibole is found in these |  | | Journal (article/letter/editorial) | | later CO2-poor fluids precipitated Ca-zeolites, prehnite and pumpellyite. Vesicular parts of flows typically...Ca-zeolites, prehnite, pumpellyite and rare epidote suggests uppermost zeolite facies to lowermost prehnite–pumpellyite...sequences is very common and occurs in response to ocean-floor, hydrothermal, thermal, burial and subduction...white mica, and titanite with less common calcite, prehnite and pumpellyite. Augite phenocrysts Table 1 Representative...pumpellyite. Other vugs consist of laumontite, prehnite and quartz with minor calcite, chlorite-smectite |  | Delacour, Adélie, Früh-Green, Gretchen L., Frank, Martin, Gutjahr, Marcus, Kelley, Deborah S. (2008) Sr- and Nd-isotope geochemistry of the Atlantis Massif (30°N, MAR): Implications for fluid fluxes and lithospheric heterogeneity. Chemical Geology, 254 (1) 19-35 doi:10.1016/j.chemgeo.2008.05.018 | Journal (article/letter/editorial) | | City A B S T R A C T The Atlantis Massif (Mid-Atlantic Ridge, 30°N) is an oceanic core complex marked...with basalts, gabbros and/or peridotites in mid-ocean ridge environments is a first order process that...the intersection between the slow-spreading Mid-Atlantic Ridge and the Atlantis Transform Fault. Based...Green hatched line: trace of the detachment shear zone (DSZ) at the top of the massif (Karson et al., 2006);...al., 2005). Recent drilling of the Integrated Ocean Drilling Program (IODP) at the central dome of the |  | | Journal (article/letter/editorial) | | have been determined for a well-defined alteration zone at 240°C and I 10 bars at Svartsengi, Iceland. Mass...phaseschlorite, epidote, albite, quartz, calcite, prehnite, anhydrite, pyrite and magnetite, whereas remnant...provide insight into processes of alteration of mid-ocean ridge basalt (MORB). Comparisons with altered MORB...is the direct landward continuation of the Mid-Atlantic Ridge. The Grindavik fissure swarm, which is tectonically...of low rcsistivn: to the south-west of the upflow zone suggests natuml discharge of the geothermal fluid |  | | Journal (article/letter/editorial) | | history of the intrusion, producing secondary, fracture-filling mineral assemblages that range from upper...(Norton et al. 1984; Bird et al. 1986). Similar fracture-controlled hydrothermal alteration initiated at...during the early stages of opening of the North Atlantic ocean (Brooks and Gleadow 1977; Brooks and Nielsen...or in complex splays and networks at granophyre fracture terminations (see Norton etal. 1984, Fig. 12)...and hornblende - actinolite - albite - epidote - prehnite (Bird et al. 1986). The latter two vein types |  | | Book | | PETROLOGY OF THE OCEAN FLOOR FURTHER TITLESIN THISSERIES 1 J.L. MERO THE M I N E R A L RESOURCES OF...MICROBIOLOGY O F OCEANS A N D ESTUAR IES 4 G _ . NEUMANN OCEAN CURRENTS 5 N.G.JERLOV OPTICAL OCEANOGRAPHY 6 V....A Y E V TEMPERATURE-SALINITY ANALYSIS OF WORLD OCEAN WATERS 12 E.J. FERGUSON WOOD and R.E. JOHANNES TROPICAL...FUNDAMENTALS OF OCEAN DYNAMICS 17 R.A.GEYER SUBMERSIBLES A N D THEIR USE I N OCEANOGRAPHY A N D OCEAN ENGINEERING...TURBULENCE 20 P.H. LEBLOND and L.A. MYSAK WAVES IN T H E OCEAN 21 C.C. VON DER BORCH (Editor) SYNTHESIS OF DEEP-SEA |  | | Journal (article/letter/editorial) | | corundum, diaspore, chlorite, kaolinite, pumpellyite, prehnite, epidote, titanite, anatase, pyrite and chalcopyrite...complex is a basement exposure within the Sakarya Zone, Eastern Pontides (Fig. 1). Within this complex...actinolite, epidote=clinozoisite, pumpellyite, prehnite, titanite, anatase, albite, quartz, pyrite, chalcopyrite...former cordierite and sillimanite, while epidote, prehnite and albite preferentially occur in former plagioclase...plagioclase-rich metapsammitic layers, pumpellyite and prehnite may be present as well. K-feldspar (only present |  | | Journal (article/letter/editorial) | | from the bulk composition Schiffman, 1983) or prehnite-pumpellyite facies I I mix are compatible with...representative compositions of pumpellyites from prehnite-pumpellyite (composition 11) and zeolite facies...10 wt. % F e 2 0 3 and 2.80 wt. % FeO) from a prehnite and zeolite paragenesis in Italy, with a cell...also illustrated. Pumpellyites in zeolite and prehnite-pumpellyite facies assemblages are invariably...decompose to assemblages of epidote f chlorite f prehnite k magnetite depending on the composition of pumpellyite |
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