Trace elements in fresh, metamorphosed and weathered ocean floor basalts.

by R. A. Heath

Publisher: University ofEast Anglia in Norwich

Written in English
Published: Downloads: 733
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Thesis (M.Phil.) - University of East Anglia, School of Environmental Sciences, 1978.

The Physical Object
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  [30] Compositionally, the glass shards are similar to mid‐ocean ridge basalts; however, the water‐rock ratios experienced by the OJP tuffs were likely much higher than pillow basalts on the seafloor. This suggests that porosity and permeability, which control the flow of seawater and nutrients, may be limiting factors in microbial attack on. Analyses of major element oxides and selected trace elements of 14 samples of basic and one sample of acid tholeiitic rocks are given in table 1. Their SiO 2 contents range from wt.% to wt.% while the silica content of pla-giogranite is %. Chemical behavior of major and trace elements is described using MgO as differentiation. Mid-ocean ridge basalts (MORB) and their intrusive equivalents, gabbros, are the characteristic igneous rocks formed at mid-ocean ridges. They are tholeiites particularly low in total alkalis and in incompatible trace elements, and they have relatively flat rare earth element (REE) patterns normalized to mantle or chondrite values. In contrast. We report major-element, trace-element, and radiogenic-isotope analyses on 49 samples from Grenada, Isle de Caille, Kick ’em Jenny, and Union and Mayreau islands as well as 35 40 Ar/ 39 Ar ages from Grenada and Union. Our results show that the exposed volcanic edifice on Grenada is young, mostly less than 6 million years old.

  Eleven samples of gabbros were analysed for major and trace elements and three for rare earth elements (REE). The samples were crushed in a jaw crusher. The weathered surfaces were removed and the fresh parts were powdered using a tungsten . Petrological and geochemical characterization (major element, trace element and Pb isotopes) is done on 11 rock and 13 glass samples from dykes in selected sites in the island of Kaua’i ( Ma). Petrography of hand sample and thin section indicate dykes are composed of tholeiitic basalt and picritic basalt. Major element analyses show all dykes are tholeiitic with consistent enrichment. Analysis of fresh volcanic glass of pillow and dike margins, however, can largely surmount this difficulty, as evidenced by the extensive major-element data set of Pearce and Robinson (), and trace-element and isotopic analyses (e.g., Rautenschlein et al., ), which demonstrate an . The second half of the past century witnessed a remarkable paradigm shift in approach to the understanding of igneous rocks. Global literature records a change from a classical petrographic approach to emphasis on mineral chemistry, trace element characteristics, tectonic setting, phase relations, and theoretical simulation of magma generation and evolution processes.

Metamorphosed basalts are also important hosts for a variety of hydrothermal ore deposits, including gold deposits, copper deposits, volcanogenic massive sulfide ore deposits and a few others.   This paper presents the first comprehensive major and trace element data for ∼ abyssal peridotite samples from the Pacific and Indian ocean ridge–transform systems. The data reveal important features about the petrogenesis of these rocks, mantle melting and melt extraction processes beneath ocean ridges, and elemental behaviours. Although abyssal peridotites are serpentinized, and . Each stage has characteristic variations in Pb-Sr-Nd-Hf isotopic composition and trace element enrichment that are remarkably similar to the systematics observed in Hawaii: (1) The most voluminous, basal "shield building{\textquoteright}{\textquoteright} stage, the Flank Transitional Series (FTS), displays slightly isotopically enriched.

Trace elements in fresh, metamorphosed and weathered ocean floor basalts. by R. A. Heath Download PDF EPUB FB2

Other trace element contents of the basalt from this site are similar to those from Site although Cr and Ni are somewhat less. Hole A Nine basalt samples were analyzed from this hole.

Large variations are shown by RE and other trace elements. Fox example, the Cr varies from to ppm, Ni from 42 to ppm, Co from 42 to 62 ppm,Cited by: 1. Characterized by low concentrations of incompatible elements. (a.k.a. Olivine tholeiites) OIB (ocean island basalts) - typical of the Hawaiian and Icelandic volcanoes, these are olivine-tholeiites, having Ca-plagioclase, pyroxenes and ± olivine.

They are enriched relative to MORB in volatiles, alkali and incompatible elements. 1 Lecture 5 - Trace Elements in Seawater Trace Elements – Those elements that do not contribute to the salinity. All elements are present in concentrations less than 1mg kg-1 Many of these elements are present at very low concentrations (as low as M).

1 ppm is equivalent to 1oz of salt in 32 tons of potato chips. 1 ppb is like 1 drop of gin inlitersFile Size: KB. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. MAJOR AND TRACE ELEMENT VARIATIONS IN BASALTS FROM LEG Alistair N.

Baxter2 ABSTRACT Basalts recovered from Sites (34 Ma), (64 Ma), (49 Ma). The study focuses on the distribution of B, Be, Li, rare earth elements (REE), high-field-strength elements (HFSE), Th, U and Pb in fresh metamorphosed and weathered ocean floor basalts.

book hydrothermally altered ocean island basalts (OIB) from. These rocks are alkali-poor basalts very rich in TiO 2, relatively rich in FeO relative to MgO, relatively rich in incompatible trace elements (REE 20– × chondritic and higher in Apollo 11 than Apollo 17 samples), with marked negative Eu anomalies (Eu/Eu * ∼08–03).

These magmas have been suggested to represent either (i) very. INTRODUCTION. The recognized method of classifying most volcanic rocks is the total alkali–silica (TAS) diagram (Le Bas et al.,).The total alkali (Na 2 O + K 2 O) axis mainly distinguishes alkalic from sub-alkalic rock types, whereas the silica axis mainly distinguishes primitive from evolved rock types.

This diagram does, however, have limited application to volcanic arc lavas. As F 1 the concentration of every trace element in the liquid = the source rock (CL/CO 1) As F 1 CL/CO 1 C C 1 Di (1 F) F L O = - + Figure Variation in the relative concentration of a trace element in a liquid vs.

source rock as a fiunction of D and the fraction. ocean-floor sediments D. lake sediments E. limestone. metamorphic trace mineral D.

metamorphic mica mineral D. basalts E. silicates. Geology Chapter 7 40 terms. Annie_Strnisha. Chapter 8 - Metamorphic Rocks 37 terms. Chase_Keltgen. GEOL 8. Start studying Flood Basalts. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

There are trace element signatues of crustal contamination and mixed magmas in the later eruptions. raised earth's temperatures by near 5 degrees. This plume began to form a new ocean floor, at a doubled rate for 5 million.

Approximately two thirds of the Earth are covered by large ocean basins submerged under, on average, a m deep layer of water. The oceanic crust is dominated by basalts, gabbros and exposed mantle rocks and has a limited age of approximately 0– Ma due to constant recycling (e.g., Müller et al.

).This contrasts with the elevated continents that comprise a diverse rock. The usefulness of other elements in distinguishing between the magma types was investigated by using published analyses and comparing within-group and between-group variations.

The most successful in this respect were Cr, Ni and Ba. Cr and Ni are generally lower in volcanic arc basalts than in ocean-floor basalts. I Sources of analytical data In metamorphosed areas, ortho-amphibolites may be distinguished from para-amphibolites using the chemical criteria described by Leake [8], and Van de Kamp [9 Spilitic rocks are generally regarded as degraded basalts [10,11], and for most major elements other than CaO, Na20, and K20 show a correspondence with fresh.

Major element variations in ocean-floor basalts. Johnson Robin Cann; Published: 04 February Page(s): Weathered And Metamorphosed Basalts. Altered basalts from Swallow Bank, an abyssal hill in the NE Atlantic, and from a nearby seamount Tectonic evolution and trace element composition of basement rocks of the Mid-Atlantic Ridge: 8.

Trace element patterns of Naxos metabasaltic rocks (NA-3, NA) share many characteristics with oceanic island basalts (OIB) (Figure 7c): low Zr/Nb (i.e., ~5) relative to N-MORB, high Nb/Y, and the negative gradient in the Ti–Yb(Y) part of the diagram, which are characteristics of enriched ocean-island basalts (OIB).

This is distinct from. MORB basalts and their intrusive equivalents, gabbros, are the characteristic igneous rocks formed at mid-ocean ridges. They are tholeiites particularly low in total alkalis and in incompatible trace elements, and they have relatively flat REE patterns normalized to mantle or chondrite values.

In contrast, alkali basalts have normalized. The present restriction of ORT type basalts to ocean ridges has not to be assumed for the geologic past. According to experimental evidence mineral composition and major and trace element geochemistry of ORT basalts can be derived from relatively large degrees of partial melting of mantle rocks at shallow depth (10–15 kb).

Because MORB basalt is considered a key to understanding plate tectonics, its compositions have been much studied. It is a type of rock that is abundantly found in the crust of the Earth, and although now found very commonly on land, most ocean floor areas are underlain with basalt that covers a large percentage of the Earth.

km². Field Low K - Tholeiites: A,B Ocean Floor Basalts: B Calc - Alkaline Basalts: B,C Within Plate Basalts: D Fig.

8: Hf-Th-Ta discrimination diagram (after Wood, ) for the basaltic rocks indicating the tectonic environment. Fig.

9: Nb-Y-Ce discrimination diagram (after Eby, ,) for the basaltic rocks. In terms of the trace and minor element data, the Eua igneous suite is similar in many respects to ocean-floor basaltic lavas, although perhaps characterized by lower TiO2, Ni, and Cr than is.

Ocean-Floor Sediments Sediment on the seafloor originates from a variety of sources, When these hot solutions are injected into the cold sea water the leached chemical elements precipitate from the cooling water, leading to hydrothermal sediments near the mid-ocean ridge that are enriched in iron, manganese, copper, zinc, and other metals.

The basalts may have undergone evolution by gabbro fractionation within the lu-nar crust, perhaps in large lava lakes now solidified as the lunar maria.

The existing model involving a global magma ocean and plagioclase flotation to form the lunar crust arises solely from the incorrect assumption that the basalts are primary magmas. Basalt (US: / b ə ˈ s ɔː l t, ˈ b eɪ s ɒ l t /, UK: / ˈ b æ s ɔː l t, ˈ b æ s əl t /) is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon.

More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content. Included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau.

High and low titanium basalts; Mid-ocean ridge basalt (MORB) is a tholeiitic basalt commonly erupted only at ocean ridges and is characteristically low in incompatible elements. [4] [5]. deposits, intercalated between the flows of ocean floor basalts like those from the Mures ophiolitic suture 1, which is not the case in the present study.

On the ocean floor the carbonate rocks may undergo both the ocean floor metamorphism and the regional metamorphism. Such carbonate rocks (limestones, dolomites, ankerites and rhodochrosites).

Major Element Variations in Ocean-Floor Basalts. Major Element Variations in Ocean-Floor Basalts (pp. ) Weathered and Metamorphosed Basalts. Altered Basalts from Swallow Bank, an Abyssal Hill in the NE Atlantic, and from a Nearby Seamount Tectonic Evolution and Trace Element Composition of Basement Rocks of the Mid-Atlantic Ridge.

The pillow basalts and dolerite slices have similar major and trace element concentrations. SiO 2 ranges from to wt.%, with high TiO 2 (– wt.%) contents. FeO T and MgO range widely from to wt.% and from to wt.%, respectively (Table S2). Basalt (pronounced / b ə ˈ s ɔː l t /, / ˈ b æ s ɒ l t / or / ˈ b æ s ɔː l t /) is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon.

Flood basalt describes the formation in a series of lava basalt flows. Contents[show] Definition By definition, basalt is an aphanitic (fine-grained. Basalts are strongly altered/weathered: the basalt considered on the field as “the freshest”, meaning “poorly weathered”, actually lost much of its primary minerals and textures (Figure 3b), while the most altered/weathered one is composed of three layers of different colors and compositions (Figure 3c).

Deep Sea Drilling Project Reports and Publications. The latter is now the favoured explanation. Many of the samples of ocean crust recovered from the ocean floor by drillling or dredging are altered. Metamorphism Cann () recognises 5 different mineral assemblage facies in oceanic basalts recovered by dredging, drilling etc.

The rocks characteristically preserve igneous textures. (1.Metamorphic rock - Metamorphic rock - Regional metamorphism: Regional metamorphism is associated with the major events of Earth dynamics, and the vast majority of metamorphic rocks are so produced.

They are the rocks involved in the cyclic processes of erosion, sedimentation, burial, metamorphism, and mountain building (orogeny), events that are all related to major convective processes in.A.

Y. Ozerov, The evolution of high-alumina basalts of the Klyuchevskoy volcano, Kamchatka, Russia, based on microprobe analyses of mineral inclusions. Journal of Volcanology and Geothermal Research, v.

95, pp. 65–79 (). A. W. Hofmann, Sampling mantle heterogeneity through oceanic basalts: isotopes and trace elements. Treatise on Geochemistry Volume 2, pages 61– Elsevier Ltd. ().