Overview
SIST ISO 710-3:1995 is an international standard published by the International Organization for Standardization (ISO) that establishes a consistent set of graphical symbols for representing magmatic rocks on detailed maps, plans, and geological cross-sections. This standard-Part 3 of a series on geological graphical symbols-focuses specifically on the depiction of various magmatic rock types through a unified system of symbols and ornaments. These symbols are designed to allow clear, precise geological communication, essential for geologists, cartographers, and engineers working with detailed geological data.
Key Topics
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Scope and Purpose
SIST ISO 710-3:1995 provides a logical, expandable system of symbols for magmatic rocks, enabling consistent representation on geological maps and cross-sections. The standard differentiates symbols between principal magmatic rock types and additional varia symbols for special cases, ensuring comprehensive coverage.
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Classification of Symbols
The symbols are divided into two main groups:
- Main Types – Represent principal magmatic rocks such as plutonic and volcanic rocks, classified according to their silica content and texture (coarse-grained, fine-grained, porphyritic, etc.).
- Varia – Includes supplementary symbols for tuffs, lavas, volcanic glasses, dyke rocks, and miscellaneous volcanic rocks that do not fit into the main system.
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Symbol Design Principles
- Plutonic rocks’ symbols derive from crosses (+) or the letter “Y,” modified by line thickness or additional marks for detailed classification.
- Volcanic rocks’ symbols are based on a right angle on its point (v) and are similarly modified to indicate chemical composition or texture.
- Texture and grain-size differences are shown by varying symbol size or by alternation to indicate porphyritic texture.
- Symbol modifications indicate rock acidity/basicity, age variations, and textural properties.
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Specific Symbol Examples
- Alkali granite and trachyte symbols include open spaces at line intersections.
- Ultrabasites use line-length variations to reflect their characteristics.
- Paleo-volcanic and neo-volcanic rocks are distinguished by including a point at the intersection in the symbol.
- Tuffs, pumiceous lava, obsidian, and other volcanic-related materials have unique, specially designated symbols in the varia section.
Applications
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Geological Mapping
SIST ISO 710-3:1995 is fundamental for geologists creating detailed geological maps that include the representation of magmatic rock formations, ensuring standardized and unambiguous communication of rock types.
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Geological Cross-Sections
The symbols facilitate accurate cross-sectional views of subsurface geology, crucial for mining, construction, and petroleum exploration where the identification of igneous bodies is important.
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Educational and Scientific Materials
The standard is useful for textbooks, academic publications, and scientific illustrations requiring standardized graphical representations of magmatic rocks.
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Engineering and Environmental Studies
Engineering geologists and environmental professionals use these symbols in site investigations and risk assessments where magmatic rock identification affects project planning.
Related Standards
SIST ISO 710-3:1995 is part of a broader series on graphical symbols for geological representation:
- ISO 710-1: General Rules – Defines general principles for graphical symbols on maps and plans.
- ISO 710-2: Sedimentary Rocks – Covers symbolization for sedimentary rock types.
- ISO 710-4: Metamorphic Rocks (in preparation) – Will address symbols for metamorphic rocks.
- ISO 710-5: Minerals (in preparation) – Planned standard for mineral representation.
Adhering to all parts of this series ensures comprehensive standardization across geological mapping disciplines.
Keywords: SIST ISO 710-3:1995, graphical symbols, magmatic rocks, geological maps, geological cross-sections, plutonic rocks, volcanic rocks, magmatic rock representation, geological mapping standards, sedimentary rock symbols, geological symbolization, geological cartography, International Organization for Standardization.