The Proxy Observation Ontology
type: Ontology
version IRI: http://linked.earth/ontology/observation/1.0.0
creator: ~khider
contributor: dgarijo
creator: ~npm4
version info: 1.0.0
preferred namespace prefix: le
contributor: ~gil
creator: http://orcid.org/0000-0001-5920-4751
license: http://creativecommons.org/licenses/by/2.0/

Assemblage
type: Class
subclass of: Proxy observation

Chemical
type: Class
subclass of: Proxy observation

Composition
type: Class
subclass of: Physical observation

Diffraction
type: Class
subclass of: Spectral observation

Fluorescence
type: Class
subclass of: Spectral observation

Isotope
type: Class
subclass of: Chemical
comment: Atoms can be simply described as consisting of protons, electrons, and neutrons. Isotopes of the same element differ by the number of neutrons in the nucleus, resulting in different mass.

Major element
type: Class
subclass of: Chemical

Organic index
type: Class
subclass of: Chemical
comment: Paleoceanographers use the term biomarker to describe organic molecules found in marine sediments, initially produced by a variety of organisms either on land or in the marine environment [1]. A key characteristic of biomarkers is their ability to survive deposition in the archive in terms of their original structure and steroidal configuration (i.e., spatial distribution of the atoms) [1]. Their usefulness for paleoceanographic reconstructions largely depends on their degradation within the archive [1]. ? 1.0 1.1 1.2 Rosell-Melé, A., & McClymont, E. L. (2007). Biomarkers as Paleoceanographic proxies. Developments in Marine Geology, 1, 441-490. doi:10.1016/S1572-5480(07)01016-0

Physical observation
type: Class
subclass of: Proxy observation

Proxy observation
type: Class

Radioisotope
type: Class
subclass of: Isotope

Reflectance
type: Class
subclass of: Spectral observation

Spectral observation
type: Class
subclass of: Proxy observation

Stable Carbon isotope
type: Class
subclass of: Stable isotope
comment: Carbon in nature exists in oxidized (i.e., CO2 and carbonates), elemental (i.e., graphite and diamond), and reduced (i.e., methane and organic matter]) forms. Carbon has two stable isotopes: the light isotope 12C (abundance: 98.9%, mass: 12.000000 amu) and the heavy isotope 13C (abundance: 1.1%, mass: 13.003355 amu). Since the mass of 13C is higher than the mass of 12C, the carbon isotopes are fractionated by chemical and biological processes. In general, 12C is strongly partitioned into organic matter (reduced form) while the heavy isotope is concentrated in the oxidized forms of carbon.

Stable Hydrogen isotope
type: Class
subclass of: Stable isotope

Stable isotope
type: Class
subclass of: Isotope

Stable Nitrogen isotope
type: Class
subclass of: Stable isotope

Stable Oxygen isotope
type: Class
subclass of: Stable isotope

Stable sulfur isotope
type: Class
subclass of: Stable isotope

Trace element
type: Class
subclass of: Chemical

Ar-Ar
type: NamedIndividual
type: Radioisotope

C
type: NamedIndividual
type: Major element

Clay fraction
type: NamedIndividual
type: Composition

Color
type: NamedIndividual
type: Physical observation

Density
type: NamedIndividual
type: Physical observation

Diffuse spectral reflectance
type: NamedIndividual
type: Reflectance

Faunal
type: NamedIndividual
type: Assemblage

Floral
type: NamedIndividual
type: Assemblage

Grain size
type: NamedIndividual
type: Physical observation

Historic
type: NamedIndividual
type: Proxy observation

Layer thickness
type: NamedIndividual
type: Physical observation

Lead Isotope
type: NamedIndividual
type: Radioisotope

Lithics
type: NamedIndividual
type: Physical observation

Luminescence
type: NamedIndividual
type: Spectral observation

Magnetic susceptibility
type: NamedIndividual
type: Physical observation

Mineral matter
type: NamedIndividual
type: Chemical

Moisture Content
type: NamedIndividual
type: Physical observation

N
type: NamedIndividual
type: Major element

Neodymium
type: NamedIndividual
type: Radioisotope

Organic matter
type: NamedIndividual
type: Chemical

P
type: NamedIndividual
type: Major element

Permeability
type: NamedIndividual
type: Physical observation

Porosity
type: NamedIndividual
type: Physical observation

Radiocarbon
type: NamedIndividual
type: Radioisotope

Resistivity
type: NamedIndividual
type: Physical observation

Sand fraction
type: NamedIndividual
type: Composition

Si
type: NamedIndividual
type: Major element

Silt fraction
type: NamedIndividual
type: Composition

TEX86
type: NamedIndividual
type: Organic index
comment: The use of TEX86 (TetraEther indeX of 86 carbons) as a tool to reconstruct past sea surface temperature variability is based on the relative cyclization of isoprenoidal glycerol dialkyl glycerol tetra ethers (GDGTs) produced by marine archaea. TEX86 is defined as [1]: TEX_{86}=\frac{GDGT-2+GDGT-3+Cren'}{GDGT-1+GDGT-2+GDGT-3+Cren'} where GDGTs 1-3 indicate compounds containing 1-3 cyclopentyl moieties, respectively, and Cren' denotes the regioisomer of crenarchaeol, a diagnostic biomarker for the Thaumarchaeota, the primary producers of GDGTs in the marine realm. By definition, values of the TEX86 index are comprised between 0 and 1. Experimental evidence suggests that archaea produce GDGTs with more rings warmer waters, a response observed in cultures of hyperthermophile archaea [2] [3] and mesocosm experiments with natural seawater containing heterogenous archaeal population [4] [5]. References [1] Schouten, S., Hopmans, E. C., Schefuß, E., & Sinninghe Damsté, J. S. (2002). Distributional variations in marine crenarchaeotal membrane lipids: a new organic proxy for reconstructing ancient sea water temperatures? . Earth and Planetary Science Letters, 204, 265-274. [2] de Rosa, M., Esposito, E., Gambacorta, A., Nicolaus, B., & Bu'Lock, J. (1980). Effects of temperature on ether lipid composition of Caldariella acidophilia. Phytochemistry, 19, 827-831. [3] Uda, I., Sugai, A., Itoh, Y., & Itoh, T. (2001). Variation in molecular species of polar liipds from Thermoplasma acidophilum depends on growth temperature. Lipids, 36, 103-105. [4] Wuchter, C., Schouten, S., Coolen, M. J. L., & Sinninghe Damsté, J. S. (2004). Temperature-dependent variation in the distribution of tetraether membrane lipids of marine Crenarchaeota: implications for TEX86 paleothermometry. Paleoceanography, 19, PA4028. doi:10.1029/2004PA001041 [5]Schouten, S., Forster, A., Panato, E., & Sinninghe Damsté, J. S. (2007). Towards the calibration of the TEX86 paleothermometer on ancient greenhouse worlds. …

U-Th
type: NamedIndividual
type: Radioisotope

Uk37
type: NamedIndividual
type: Organic index
comment: The C37 alkenone unsaturation index ( U_{37}^{k'} ) is a firmly established tool for past sea surface temperatures reconstruction and is based on the relative abundance of di- (C37:2) and tri- (C37:3) unsaturated ketones with 37 carbon atoms. The index varies between 0 and 1, thus it may saturate in the temperature extremes as it becomes more challenging to determine since C37:3 and C37:2 alkenones approach their detection limits. Since alkenones come exclusively from a few species of haptophyte algae which require sunlight, alkenone thermometry offers the advantage of direct estimate of near-surface ocean temperatures. The ubiquitous presence of alkenone-synthesizing organisms (most commonly the coccolithophorids Emiliania huxleyi and Gephyrocapsa oceanic through the world's ocean and the rapidity and high-precision of the alkenone analyses had made U_{37}^{k'} a valuable proxy for paleoceanographic reconstructions. However, the U_{37}^{k'} proxy is subject to non-temperature effects, such as lateral transport through oceanic currents (Ohkouchi et al. (2002)) and preferential post-depositional oxidation of C37:3 compared to C37:2 [1] [2]. Furthermore, changes in the seasonality of the proxy (i.e., which part of the seasonal cycle the proxy is recording) may bias the inferred temperatures toward winter or summer conditions [3]. Finally in oceanic regions where the photic zone extends below the surface mixed layer, the sedimentary signal may not strictly represent sea surface temperatures but rather a composite temperature of the mixed layer and the thermocline [4][5]. References [1] Hoefs, M. J. L., Versteegh, G. J. M., Rijpstra, W. I. C., de Leeuw, J. W., & Damsté, J. S. S. (1998). Postdepositional oxic degradation of alkenones: Implications for the measurement of palaeo sea surface temperatures. Paleoceanography, 13(1), 42-49. doi:10.1029/97pa02893 [2] Ohkouchi, N., Eglinton, T. I., Keigwin, L. D., & Hayes, J. M. (2002). Spatial and temporal offsets between proxy …

Uk 37'
type: NamedIndividual
type: Organic index
comment: The currently accepted U37kprime (Prahl and Wakeman, 1987) varies positively with temperature, and is defines as C(37:2)/(C(37:2)+C(37:3), where C(37:2) represents the quantity of the di-unsaturated ketone and C(37:3) the quantity of the tri-unsaturated form. Herbet, T.D., 2003, Alkenone paleotemperature determinations in Treatise on Geochemistry, Volume 6, pp 391-432

X-Ray diffraction
type: NamedIndividual
type: Diffraction

X-ray fluorescence
type: NamedIndividual
type: Fluorescence

d13C
type: NamedIndividual
type: Stable Carbon isotope

d15N
type: NamedIndividual
type: Stable Nitrogen isotope

d170
type: NamedIndividual
type: Stable Oxygen isotope

d180
type: NamedIndividual
type: Stable Oxygen isotope
comment: Oxygen has three naturally-occuring stable isotopes: 16O, 17O, 18O, with 16O being the most abundant (99.762%). Two international reference standards are used to report variations in oxygen isotope standards: PDB and SMOW. The use of the PDB standard in reporting oxygen isotope composition is restricted to carbonates of low-temperature origins (e.g., oceanic, lacustrine ). The conversion between SMOW and PDB scales is given by: \delta^{18}O_{SMOW} = 1.03091 (\delta^{18}O_{PDB}) +30.91 δ18O may be measured on the shells of foraminifera

d34S
type: NamedIndividual
type: Stable sulfur isotope

dD
type: NamedIndividual
type: Stable Hydrogen isotope

Al/Ca
type: NamedIndividual
type: Trace element

B/Ca
type: NamedIndividual
type: Trace element

Ba/Ca
type: NamedIndividual
type: Trace element

Fe/Ca
type: NamedIndividual
type: Trace element

Li/Ca
type: NamedIndividual
type: Trace element

Mg/Ca
type: NamedIndividual
type: Trace element

Mn/Ca
type: NamedIndividual
type: Trace element

Sr/Ca
type: NamedIndividual
type: Trace element

Zn/Ca
type: NamedIndividual
type: Trace element