Documents about Oxygen Isotope

  • 3 Pages

    Oisotope29Mar04

    ASU, GLG 485

    Excerpt: ... w similar behavior except that "17O = -0.25. This line intersects (most) pallasites (iron + olivine) and the Type IIIAB iron meteorites (1st transparency). More work could be done to examine relations within these classes (good proposal). Summary of Moon, Achondrites Within these bodies (representing Mars, the eucrite parent body, and the Moon) there is a ~<2 range in !18O, while rocks on the Earth show a much wider range. Why? Water reacts with terrestrial rocks and changes their isotope composition. Subduction mixes fractionated oxygen isotope s into the mantle. These processes have not occurred (?) on the other bodies O Isotopes in Chondrites Whole rocks. Different chondrite types are (usually) not related by mass-dependent fractionation lines. For example, different CM chondrites do not form an array like the SNC meteorites. Chondrites are mixtures of components with very different O isotopic compositions. Need to study these components: CAIs, chondrules. O Isotopes in CAIs The larges ...

  • 1 Pages

    5_3_2_Between_Oxygen_Scales

    Penn State, GEOSC 5

    Excerpt: ... 5.3.2 -15.3.2 Conversion Between Oxygen Isotope Reference Scales Print this Section Save Zoom When isotope fractionation occurs in the sample preparation procedure, the conversion of the measured isotopic compositions to a reporting scale needs to take this into account. As an example we consider the case of oxygen isotopic composition measurements, where several fractionation factors can be involved. To report oxygen isotope s one has used frequently the PDB, VPDB, SMOW and VSMOW scales. For geochemical discussions all results need to be referred to one scale and thus conversions may be necessary. The need to convert between oxygen isotopic composition scales arises, for example, when one would like to compare results from different researchers, or one wishes to use one measurement reference gas for the analyses of waters, silicates, and carbonates. When only water isotopic compositions are investigated, the analyst might choose a water sample as measuring reference and calibrate it directly using VSMOW. The ...

  • 2 Pages

    geol1020hw4

    Colorado, GEOL 1020

    Excerpt: ... Homework #4, Geol 1020, Spring 2008 1. Which of the following is NOT geologic evidence for glaciation and/or climate change in the Pleistocene? A. oxygen isotope s in marine shells B. unsorted and unlayerd conglomerates (tills) C. pollen in lake sediments D. abundance of gasses in ice cores E. all of the above are evidence for glaciation and/or climate change solar 2. Fill in the blank with one word - The earth's climate is an engine driven by _ energy. 3. Why does the oxygen isotopic ratio of seawater change in a glacial period relative to a non-glacial period? A. the 16O isotope of oxygen selectively concentrates in the oceans when glacial ice sheets are growing B. the 18O isotope of oxygen selectively concentrates in the oceans when glacial ice sheets are growing C. the 18O isotope of oxygen selectively concentrates in ice when glacial ice sheets are growing C. the 18O isotope of oxygen selectively concentrates in ice when glacial ice sheets are melting 4. When geologists work with the is ...

  • 2 Pages

    geo hw 4

    Colorado, GEOL 1020

    Excerpt: ... Homework #4, Geol 1020, Spring 2008 1. Which of the following is NOT geologic evidence for glaciation and/or climate change in the Pleistocene? A. oxygen isotope s in marine shells B. unsorted and unlayerd conglomerates (tills) C. pollen in lake sediments D. abundance of gasses in ice cores E. all of the above are evidence for glaciation and/or climate change 2. Fill in the blank with one word - The earth's climate is an engine driven by _SOLAR_ energy. 3. Why does the oxygen isotopic ratio of seawater change in a glacial period relative to a non-glacial period? A. the 16O isotope of oxygen selectively concentrates in the oceans when glacial ice sheets are growing B. the 18O isotope of oxygen selectively concentrates in the oceans when glacial ice sheets are growing C. the 18O isotope of oxygen selectively concentrates in ice when glacial ice sheets are growing C. the 18O isotope of oxygen selectively concentrates in ice when glacial ice sheets are melting 4. When geologists work with the isotope ...

  • 3 Pages

    PSRD-EarthMoonFormation

    University of Hawaii - Hilo, FEB 08

    Excerpt: ... Compositional Balancing Before Moon Formation A striking feature of the Earth and Moon is that they have identical oxygen isotopic compositions, in spite of considerable variation throughout the solar system. PSRD presents www.psrd.hawaii.edu/Feb08/EarthMoonFormation.html Compositional Balancing Before Moon Formation Painting by James Garry Planet formation involved substantial mixing throughout inner solar system as planetary embryos accreted. Considering the variability in Oisotopes throughout the solar system, why do Earth and Moon have the same oxygen isotopic composition? PSRD presents Planetary embryo accretion simulation by John Chambers. Note how much mixing there is as accretion proceeds. www.psrd.hawaii.edu/Feb08/EarthMoonFormation.html Compositional Balancing Before Moon Formation Oxygen isotope s might have equilibrated between Earth and Moon via the hot silicate atmosphere surrounding the proto-Earth and proto-lunar disk. PSRD presents www.psrd.hawaii.edu/Feb08/EarthMoonFormation.html ...

  • 14 Pages

    Lecture3

    Penn State, GEOSC 412

    Excerpt: ... Mean oxygen isotopic composition in precipitation Weighted mean hydrogen and oxygen iotopic composition for worldwide stations Adiabatic cooling, relationship between temperature of condensation and the oxygen isotopic composition of the remaining ...

  • 2 Pages

    4_5_Oxygen

    Penn State, GEOSC 4

    Excerpt: ... 4.5-14.5 Preparation of Samples for Oxygen Isotopic Analysis Print this Section Save Zoom Oxygen is surpassed only by iron in its abundance in the Earth and constitutes close to 29 % of its total weight. In the Earth's crust it is by far the most ab ...

  • 20 Pages

    w12_d1_web2

    Coastal Carolina University, MARINE 112

    Excerpt: ... Today From primary productivity to: Deep sea sediments Climate change and variations Oxygen Isotope s Early Earth Test Thursday Deep Ocean Sediment From the Continents rivers glaciers dust turbidites Deposition in the Deep Sea From primary productivity Deposition in the Deep Sea organismal death Settling through the water column Deposition of decayed particles on seafloor Decomposition or burial From precipitation deep sea vents nodules Deposition in the Deep Sea Sediment Composition Inorganic materials from the land and air Mud (clay and silt) Sands and gravels Glacial sediments (till, dropstones) Organic materials from the land and sea (and air) Soft tissues Hard tests Precipitates Manganese nodules, crusts Hydrothermal vent minerals Deep Sea Sedimentation Manganese Nodules Left image from http:/web.ngdc.noaa.gov/mgg/image/nodule.gif Right image from: http:/bell.mma.edu/~jbouch/MnNodules.GIF Classifications of Sediment In ...

  • 3 Pages

    OcSci07.Hmwk6

    Arizona, GEO 412

    Excerpt: ... ity under the direction of A. Duffy and J. Imbrie. The SPECMAP Archives contains climate times series of the past 400,000 years derived for 17 sediment cores from the Atlantic Ocean. Downcore records include (1) quantitative data on planktonic species and assemblages which reflect conditions in the surface waters of the Atlantic ocean; (2) measurements of 180, 13C on fossil foraminiferan shells, stable isotope differences (planktic and benthic), and Cd/Ca ratios from foraminiferan shells, an index of paleoproductivity. Click on SPECMAP No 1 Archive (top of page). First, lets retrieve a real data set, in this case of oxygen isotope data from foraminifera from a deep sea core. Lets look at the file specmap.004, which has data from core RC-24-16. Copy the data from this file and paste into Excel. You will have to select the data and use Data Text to Columns Fixed Width to convert these data into separate columns. The data give the oxygen isotope value (18O) relat ...

  • 8 Pages

    4_4_5_Phosphates

    Penn State, GEOSC 4

    Excerpt: ... However, since that time the determination of the oxygen isotopic composition of phosphates has become of interest in other respects. For example, Longinelli and Nuti (1968) argued, on the basis of the oxygen isotopic composition of marine phosphorites, that the oxygen isotopic composition of the ocean water changed during geologic time, alternatively, changes in the ocean temperature could be proposed to explain the firmly established *18Ophosphate - time trend (e.g., Shemesh et al. 1983, 1988, Karhu and Epstein 1986). While the isotope exchange between phosphates and water is slow, even on a geologic time scale, in enzyme-catalyzed reactions the exchange between water and the phosphate ion takes place in minutes. Hence one may suppose that in biogenically formed phosphates (bones, teeth) the oxygen isotope record reflects that of the fluid present in their formation (blood), whose *18O, in turn, is governed by that of the environmental water. Because the resistance of phosphates to isotopic exchange after ...

  • 338 Pages

    648_Schedule_S09

    Texas A&M, GEOL 648

    Excerpt: ... um fractionation) (cont.) Theory (Equilibrium fractionation) (cont.) Oxygen and hydrogen isotopes (general) ds Oxygen and hydrogen isotopes in natural waters - Clark and Fritz, 1997, p. 35-51; 63-73 Meteoric waters Oxygen and hydrogen isotopes in natural waters - Petit et al., 1998 Meteoric waters (cont.) Oxygen and hydrogen isotopes in natural waters Sharp, 2007, p. 88-91, 103-108. hydrothermal and formation waters and seawater Oxygen and hydrogen isotopes in seawater and intro to igneous rocks Oxygen and hydrogen isotopes in igneous rocks Oxygen and hydrogen isotopes in metamorphic rocks Oxygen and carbon isotopes in sediments Sharp, 2007, Ch. 11, p. 242-247, Ravelo and HillaireMarcel, 2007, p. 740-746 Sharp, 2007, Ch. 11, p. 242-247, 255-264 Sharp, 2007, Ch. 11, p. 242-247, 255-264 Grossman, 2009. Oxygen isotope stratigraphy (introduction, in revision) Ravelo and Hillaire-Marcel, 2007, p. 735-740, 746-751 Same as above Lea et al., 2000 Zachos et al., 2001 Grossman, 2009; Bugguish et al., 2008 .Anderson ...

  • 1 Pages

    GEO302C-L28

    University of Texas, GEO 302C

    Excerpt: ... GEO302C 03/31/08 Lecture 28: Millennial Changes: Delta 18O in Ice Sheets Homework Definitions Dates Important People 1. Climate change at different time scales a. Tectonic: longest scale- hundreds of millions of years b. Orbital: tens to hundreds of thousands of years- cycles c. Millennial: thousands of years- oscillations 2. Oscillations recorded in Greenland Ice Cores a. Delta18O and dust help to date ice b. Early studies in 1970 c. Lots of dust mean climate was windier and more polluted d. Underlying trend of graduate glacial- interglacial changes 3. Millennial Oscillations a. Younger Dryas- during the last deglaciation i. 1500 yrs long ii. Abrupt beginnings and endings (about 10 yrs) b. Millennial Oscillations during glacial period vs. interglacial i. Very wide spacing and amplitude ii. Average spacing: 1500 yrs iii. Called Dansgaard-Oeschger cycles 4. Oxygen isotope ratios in Ice and Ocean Cores a. Ocean Cores i. D18O signals 2 influences: Temp. Change and Ice volume b. Ice cores i. D18O signals refl ...

  • 6 Pages

    8_4_The_Increment_Method

    Penn State, GEOSC 518

    Excerpt: ... 8.4 - 1 8.4 The Increment Method of Computing Oxygen Isotope Effects in Minerals Print this Section Save Zoom The study of the oxygen isotopic composition of distribution in minerals showed early on that there were systematic differences among them. Garlick (1966) observed that the oxygen isotope fractionation of silicates is related to their chemical composition, in particular the Al/Si ratio. Based on this observation, subsequently semi empirical methods for the computation of oxygen isotope effects between minerals were developed. The results, obtained by such techniques, are inherently inferior to those, which are based on the most complete understanding the vibrational properties of solids. However, semi empirical methods can still be useful to obtain a first order estimate for the isotope fractionation properties of materials, in those instances where the vibrational spectra of minerals are not well enough characterized in order to carry out the computations discussed in the last section. Schtze (198 ...

  • 8 Pages

    3_GreatIceAges

    Pittsburgh, GEO 0060

    Excerpt: ... eir sources. Handout/overhead: Fig. 30 (Flint, 1947) 3. Handout/overhead: Glacial maps of North America (Fig. 470, Chamberlin and Salisbury, 1907) and the World (Fig. 1.12, Wilson e t a l ., 2000). 4. 1 4 C dating indicates maximum extent of most recent glaciation (Last Glacial Maximum (LGM) = ~18,000 years. (Pieces of wood and other organic matter buried in sediment can be dated this way.) -Examination of patterns of end moraines and buried soil horizons on land suggests 4 or at most 5 major glaciations. - 1 4 C method becomes difficult for samples older than about 30,000 years and impossible for samples older than 75,000 years. Using 14C dating alone, all we can say is that older glacial maxima are more than 75,000 years old. B. Oxygen isotope s: A key to paleoclimate research 1. Background. a. Element: atoms that share identical chemical properties. This is a function of the number of electrons in the electron orbitals, which in turn is a direct function of the number of protons in the nucleus. Number of p ...

  • 1 Pages

    4_5_3_Silicates_and Oxides

    Penn State, GEOSC 518

    Excerpt: ... 4.5.3-14.5.3 Oxygen Isotope Analysis of Silicates and Oxides Print this section Save Zoom The study of the oxygen isotope record of silicates and oxides in rocks is interesting, because it can lead not only to temperature estimates of the formation of the mineral assemblages but also to constraints on the isotopic composition of any solutions that were present during their crystallization. Such studies can hence lead to significant insights into igneous, metamorphic, hydrothermal, ore deposition, diagenetic and sedimentary processes as well as paleoclimatic conditions. In contrast to carbonates, where the extraction of at least part of the oxygen contained in the minerals can be readily achieved, this is significantly more difficult in the case of silicates and oxides. Their oxygen can be converted to CO, and CO2 by reaction with graphite, but it is frequently liberated as O2 using a variety of fluorination reagents. In the following sections we will examine the various techniques that have been used to libe ...

  • 1 Pages

    4_5_2_Carbonates

    Penn State, GEOSC 4

    Excerpt: ... 4.5.2-14.5.2 Carbonates Print this Section Save Zoom Carbonates are an important part of the sedimentary record of the Earth's history, and their oxygen isotopic composition has attracted interest, since it can bear information about the geologic co ...

  • 1 Pages

    DETERMINING_THE_EFFECTS_OF_AQUEOUS_ALTERATION_O...

    East Los Angeles College, OPEN 8480

    Excerpt: ... Oxygen in Asteroids and Meteorites 2005 7008.pdf DETERMINING THE EFFECTS OF AQUEOUS ALTERATION ON THE DISTRIBUTION OF OXYGEN ISOTOPE S IN CARBONACEOUS CHONDRITES. A. A. Morris, L. Baker, I.A. Franchi and I.P. Wright. Planetary and Space Science Research Institute, The Open University, Milton Keynes, MK7 6AA (a.a.morris@open.ac.uk) Introduction: Carbonaceous chondrites play a key role in determining the history of the early Solar System; a knowledge of the oxygen isotope variation within these materials will not only help in our understanding of the origin and evolution of those meteorites, but also the early Solar System reservoirs from which they formed [1]. However, several problems present themselves when trying to interpret early Solar System history. One is identifying the isotopic signature of oxygen from specific component compounds in a complex mixture of materials that existed in the solar nebula, and deconvoluting this from signatures developed during parent body processing (e.g. aqueous alteration ...

  • 28 Pages

    Lecture_18_SeaLevelChanges

    Caltech, GE 112

    Excerpt: ... Lecture 18 Sea-level record of the past m illion years This record of d18O is fromplanktonic foram froma core in the subs tropical Atlantic ocean. It is a record of tem perature and ice volum for the past 130,000 years or e so. A longer record froma core in the Equatorial Pacific ocean. These are divided into tim e-rock (chronostratigraphic) units, the Marine Oxygen Isotope stages A tabulation of the Marine Oxygen Isotope ages The cyclic filling and draw ing dow of the w oceans n orld has a profound effect on processes and history along coastlines. Let's revisit the littoral clastic record, and then w turn to e'll the record of fringing coral reefs An exam fromHalf Moon Bay, central California ple Mahia peninsula, North Island, NewZealand Pasadena Palos Verdes peninsula Fringing reef terraces Ages by alpha-particle counting, ~ 1968, at Colum University bia Ages by therm ionization al m spectrom ass etry, ~ 1988, here at Caltech ...

  • 1 Pages

    Determining_the_effects_of_aqueous_alteration_o...

    East Los Angeles College, OPEN 8449

    Excerpt: ... 69th Annual Meteoritical Society Meeting (2006) 5041.pdf DETERMING THE EFFECTS OF AQUEOUS ALTERATION ON THE DISTRIBUTION OF OXYGEN ISOTOPE S IN CARBONACEOUS CHONDRITES. A. A. Morris, I. A. Franchi, L. Baker, J. Watson and I. P. Wright. Planetary and Space Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA. E-mail: a.a.morris@open.ac.uk. Background: Carbonaceous chondrites (particularly the CI, CM and CR meteorites) have the most diverse range of high and low temperature mineral phases, and display the widest range of oxygen-isotopic compositions [1,2]. There are then inherent problems when trying to interpret early Solar System history. One is identifying the isotopic signature of oxygen from specific component compounds in a complex mixture of materials that existed in the solar nebular, and deconvoluting this from signatures developed during parent body processing, of which aqueous alteration is the most wide spread. Models to account for the variations in oxygen-isotopic composition ...