The GeoSciML Earth Material package contains classes representing a description of a naturally occurring substance in the Earth.
Earth Material represents material composition or substance, and is thus independent of quantity or location. Ideally, Earth Materials are defined strictly based on physical properties, but because of standard geological usage, genetic interpretations may enter into the description as well.
v2.0.1 - all links to elements in GMD namespace 'by reference'
v2.0.2 - inserted XML declaration
An EarthMaterial composed of particles composed of EarthMaterials, possibly including other CompoundMaterials.
This class is provided primarily as an extensibility point for related domain models that wish to import and build on GeoSciML, and wish to define material types that are compound but are not rock or rock-like material. For most users of GeoSciML "RockMaterial" shoudl be used.
Term to specify the gross compositional character of a compound material. Composition as used here is loosely construed to include both chemical composition and petrograpic composition, thus multiple values may be applied to a single rock, e.g. metaluminous and alkalic, undersaturated and basic, etc. Terms would typically include broad chemical classifications such as silicate, carbonate, ferromagnesian, oxide. However, this attribute may have different terminology for different kinds of rocks - for example sandstone petrographic classification terms (e.g. feldspathic) might be placed here.
A term that represents a summary geologic history of the material. (ie, a genetic process classifier term) Examples include igneous, sedimentary, metamorphic, shock metamorphic, volcanic, pyroclastic.
A specialized CompoundMaterial that includes consolidated and unconsolidated materials as well as mixtures of consolidated and unconsolidated materials.
A property that specifies the degree to which an aggregation of EarthMaterial particles is a distinct solid material. Consolidation and induration are related concepts specified by this property. They define a continuum from unconsolidated material to very hard rock. Induration is the degree to which a consolidated material is made hard, operationally determined by how difficult it is to break a piece of the material. Consolidated materials may have varying degrees of induration (NADMSC, 2004)
A controlled concept indicating the name of the RockMaterial type (eg, quartz sandstone, basalt, muscovite schist, sand, mud, soil, saprolite).
Igneous rock definitions are governed by IUGS agreed vocabulary
The Earth Material class holds a description of a naturally occurring substance in the Earth. Earth Material represents material composition or substance, and is thus independent of quantity or location. Ideally, Earth Materials are defined strictly based on physical properties, but because of standard geological usage, genetic interpretations may enter into the description as well.
Terms to specify color of the earth material. Color schemes such as the Munsell rock and soil color schemes could be used.
Specification of the intended purpose/level of abstraction for the given EarthMaterial. Scoped name because intention is asserted by author of the data instance.
Values: Instance, TypicalNorm, IdentifyingNorm.
gmd:MD_Metadata
An EarthMaterial that belongs to the class of chemical compounds having a reduced carbon basis (as distinct from carbonates), and derived from living organisms. Includes high-carbon EarthMaterials such as bitumen, peat, and coal.
An inorganic, non-crystalline EarthMaterial (solid, liquid, or gas) that tends to flow or conform to the shape of its container. Includes glass. By convention liquid mercury is considered a mineral (examples: water, brine, glass)
A naturally occurring inorganic element or compound having a periodically repeating arrangement of atoms and a characteristic chemical composition or range of compositions, resulting in distinctive physical properties. Includes mercury as a general exception to the requirement of crystallinity. Also includes crypto-crystalline materials such as chalcedony and amorphous silica.
Name of the mineral (eg: orthoclase) or mineral family (eg: feldspar), approved by the International Mineralogical Association. (eg: http://www.mindat.org/mineralindex.php)
The FabricDescription class describes all types of fabrics associated with a CompoundMaterial (ie, tectonic, metamorphic, sedimentary, igneous fabrics or textures). It denotes a pattern, defined by one or more CompoundMaterial constituents, that is present throughout a rock body when considered at some scale. FabricDescription is defined based on the average configuration of many constituents. Penetrative fabric denotes that these constituents are distributed throughout the rock volume at the scale of observation [Passchier and Trouw, 1998], and are repeated at distances that are small relative to the scale of the whole, such that they can be considered to pervade the whole uniformly (Turner and Weiss [1963] p. 21-24; Hobbs and others [1976], p. 73; Jackson [1997]; Passchier and Trouw [1998]).
FabricDescription is distinguished from Particle Geometry based on the criteria that Particle Geometry is preserved if a CompoundMaterial is disaggregated, while FabricDescription is not defined if the material is disaggregated.
Use gml:description to capture any free text to indicate any specific or peculiar features of the described fabric in the CompoundMaterial.
Attribute to denote the type of fabric in the CompoundMaterial (eg, rapikivi texture, autobrecciation, spaced cleavage, porphyroblastic, cross-bedding). The fabricType describes a pattern, defined by one or more CompoundMaterial constituents, that is present throughout a rock body when considered at some scale. FabricDescription is defined based on the average configuration of many constituents. Penetrative fabric denotes that these constituents are distributed throughout the rock volume at the scale of observation [Passchier and Trouw, 1998], and are repeated at distances that are small relative to the scale of the whole, such that they can be considered to pervade the whole uniformly.
PhysicalDescription describes a limited but commonly used set of physical properties of Rocks and UnconsolidatedMaterials. This set is an incomplete subset of potential physical properties that could be used to describe rocks and unconsolidated materials. Revision/extension of this list is anticipated in future versions.
Material mass per unit volume
Material magnetic susceptibility, customarily measured in SI units. The ratio of induced magnetization to the strength of the magnetic field causing the magnetization.
Note that volume magnetic susceptibility is dimensionless, being magnetization (magnetic dipole moment) in amperes per metre (SI) divided by the applied field, also in amperes per metre. However, many tables of magnetic susceptibility and some instruments give cgs values that rely on different definitions of the permeability of free space than SI values. The cgs value of susceptibility is multiplied by 4pi to give the SI susceptibility value. For example, the cgs volume magnetic susceptibility of water at 20?C is -7.19x10-7 which is -9.04x10-6 in SI. The xml encoding should specify whether the uom is SI or cgs, and if in cgs provide a <gml:conversionToPreferredUnit>.
The measure of the capacity of a porous material to transmit a fluid under unequal pressure. Customary unit of measure: millidarcy
The percentage of the bulk volume of a material that is occupied by interstices, whether isolated or connected.
ParticleGeometryDescription describes particles in a CompoundMaterial independent of their relationship to each other or orientation. It is distinguished from Fabric in that the ParticleGeometryDescription remains constant if the material is disaggregated into its constituent particles, whereas Fabric is lost if the material is disaggregated. Properties include the particle size (grainsize), particle sorting (size distribution, eg: well sorted, poorly sorted, bimodal sorting), particle shape (surface rounding or crystal face development, eg: well rounded, euhedral, anhedral), and particle aspectRatio (eg: elongated, platy, bladed, compact, acicular).
[Association from ConstituentPart to ParticleGeometryDescription has been removed from GeoSciML v2 and will be re-considered from GeoSciML v3]
Terms to specify the nature of individual particles of each constituent in an Earth Material aggregation, based mostly on their genesis. If applied on ParticleDescription for CompoundMaterial, then would characterize all particles in aggregate. Use this property on CompoundMaterial to distinguish rocks composed of crystals (crystalline rocks) from rocks composed of granular particles (clasts, fragments). Examples include oolith, crystals, pore space. Constituent type is determined based on the nature of the particles, and ideally is independent of the relationship between particles in a compound material aggregation.
See discussion of particleType vs ConstituentPart.role in the scope notes for ConstituentPart.
AspectRatio describes the geometry of particles based on the ratios of lengths of long, intermediate and short axes of grains. Equates to sphericity in sedimentary rocks (ie: the degree to which the shape of a particle approximates a sphere). A quantitative specification based on the ratio of lengths of long, intermediate and short axes of grain shape (Sneed and Folk, 1958; Zingg, 1935). (eg: prolate, slightly flattened, very bladed, equant, acicular, tabular)
The Shape attribute describes, a) the development of crystal faces bounding particles in crystalline compond materials, and b) surface rounding of grains in sedimentary rocks. Roundness is a measure of the sharpness of the edges between surfaces bounding a particle (see Jackson, 1997; Wadell, 1932). Terms should be appropriate for the kind of compound material (eg: for crystalline rocks- euhedral, ideoblastic, subhedral, anhedral, xenoblastic; for sedimentary rocks - angular, rounded)
The Size attribute specifies particle grainsize. Values may be reported using absolute measurements (eg: range, mean, median, mode, maximum) or as descriptive terms from a schema appropriate to the type of Compound Material (eg: the Udden-Wentworth sheme for clastic sedimentary rocks - silt, sand, gravel; volcaniclastic rocks - ash, lapilli, bomb; crystalline rocks - fine, medium, coarse, cryptocrystalline)
The Sorting attribute holds text or numeric terms to specify size distribution of particles in a CompoundMaterial. Terminology for sorting in sedimentary rocks is based on the quantitative Graphic Standard Deviation (IGSD) scheme proposed by Folk (1968, 1974). Example terms for this attribute may include sedimentary terms such as well sorted and poorly sorted, or igneous terms such as porphyritic, equigranuilar, seriate.
MetamorphicDescription describes the character of metamorphism applied to a CompoundMaterial or GeologicUnit using one or more properties including estimated intensity (grade; eg high grade, low grade), characteristic metamorphic mineral assemblages (facies; eg, greenschist, amphibolite), peak P-T estimates, and protolith material if known.
A description of characteristic mineral assemblages indicative of certain metamorphic P-T conditions. Examples include Barrovian metasedimentary zones (eg: biotite facies, kyanite facies) or assemblages developed in rocks of more mafic composition (eg: greenschist facies, amphibolite facies).
A term to indicate the intensity or rank of metamorphism applied to an EarthMaterial (eg: high metamorphic grade, low metamorphic grade)
Indicates in a general way the P-T environment in which the metamorphism took place. Determination of metamorphic grade is based on mineral assemblages (ie, facies) present in a rock that are interpreted to have crystallized in equilibrium during a particular metamorphic event.
A numerical value to indicate the estimated pressure at peak metamorphic conditions.
A numerical value to indicate the estimated temperature at peak metamorphic conditions.
An interpretation of the EarthMaterial that constituted the pre-metamorphic lithology for this metamorphosed CompoundMaterial.
The Constituent Part class describes how Earth Materials may be made up of other Earth Materials, including the proportion of the constituent part in the whole (eg: 20%, minor, dominant); the role that the constituent plays in the whole (eg: matrix, groundmass, framework, phenocryst, xenolith, vein). The particleType property that specifies type of particle (eg: grain, clast, crystal, fossil, oolite) has been moved to the ParticleGeometryDescription data type, associated with both ConstituentPart and CompoundMaterial (GeoSciMLv2, RC3, Uppsala, Sweden).
The distinction between "role" and "particleType" is subtle. An operational test is that constituentType may be determined independent of relationship between particles in the aggregation, whereas role requires consideration of the relationship to other particles. A particle may be identified as clast, independent of its material composition, and independent of its relationship to other grains in a rock. The term 'floating clast' is a role, because it is dependent on the relationship 'not in contact with other clasts'. Consider Dunham's textural classification of carbonate rocks (wackestone, packstone, grainstone...) in the description of carbonate rocks. The description is predicated on identification of two kinds of intraclasts (grains) and matrix (carbonate mud), and then uses this distinction to establish relationships--mud supported vs. grain supported -- that define roles for the two types of constituents (framework, matrix...).
examples of type vs. role:
Particle type: clast. Role: framework, floating particle
particle type: crystal. Role: matrix, pseudomatrix (in case that matrix is interpreted as recrystallized material)
particle type: clast. Role: matrix (in case that matrix is interpreted as very-fine grained detrital fraction)
particle type: crystal. Role: cement (in case that material insterstitial to particles is crystalline material introduced during diagenesis)
particle type: crystal. Role: phenocryst (in igneous rock)
particle type: microlite Role: groundmass (in porphyrytic igneous rock)
particle type: crystal. Role: framework (in igneous rock)
particle type: pyroclast. role: framework (in tuff)
particle type: crystal Role: oikocryst
particle type: crystal Role: overgrowth
particle type: biogenic particle Role: floating particle
particle type: ooid Role: framework
The fraction of the whole that is formed by a ConstituentPart in a part/whole relationship. Used for the ConstituentPart portion in a CompoundMaterial.
Quantity that specifies the fraction of the Earth Material formed by the part (eg: 20%, minor, dominant)
The role a ConstituentPart plays in a CompoundMaterial aggregation. The same EarthMaterial may occur as different ConstituentParts playing different roles within the same CompoundMaterial. For example, feldspar may be present as groundmass (a ConstituentPart::role) and as phenocrysts (an ConstituentPart::role) within a single igneous rock.