Geology: Earth's Interior, Plate Tectonics, Minerals, and Igneous Rocks

These practice flashcards cover the essentials of Earth's interior, plate tectonics mechanisms, mineral properties and classification, and the formation and classification of igneous rocks based on the OSN Earth Science lecture notes.

Continental Crust

A layer with a thickness of $35 - 70\,\text{km}$, composed of SiAl (Silicon and Aluminium), and having a density of $2.7\,\text{gram/cm}^3$.

Oceanic Crust

A layer with a thickness of $7 - 10\,\text{km}$, composed of SiMa (Silicon and Magnesium), and having a density of $3.0\,\text{gram/cm}^3$.

Lithosphere

The outermost physical layer of the Earth, including the crust and uppermost mantle, characterized by being brittle (rapuh) with a thickness of about $100\,\text{km}$.

Asthenosphere

A ductile (liat/plastis) layer in the upper mantle between $100 - 660\,\text{km}$ depth that can flow like a fluid, allowing tectonic plates to move horizontally.

Mesosphere

A solid and hot physical layer of the Earth located at a depth between $660 - 2885\,\text{km}$, primarily composed of silicates and magnesium.

Divergent Boundary

A type of plate boundary where two adjacent plates move away from each other, potentially forming a mid-oceanic ridge or a rift valley.

Sea-floor Spreading

The mechanism in divergent zones where magma from the mantle fills the gap between separating plates, cooling to form new oceanic floor.

Continental Rifting

A process occurring in the middle of a continent under extension stress, thinning the plate and eventually splitting it into smaller landmasses.

Convergent Boundary

A boundary formed when two plates move toward each other, resulting in either subduction or collision.

Partial Melting

The process where the asthenosphere melts into magma, often caused by the release of water from subducting oceanic rocks which lowers the melting point.

Continental Volcanic Arc

A characteristic feature of oceanic-continental subduction zones, such as the Andes Mountains in South America.

Volcanic Island Arc

A characteristic feature of oceanic-oceanic subduction zones, such as the Nusa Tenggara Islands in Indonesia.

Collision Zone

A convergent zone where two continental plates collide, typically forming tectonic mountain ranges like the Himalayas.

Transform Boundary

A boundary where two plates move horizontally past each other, often manifesting as transform faults or strike-slip faults like the San Andreas Fault.

Crystallography

The science that studies and describes crystals, which are solids with a regular arrangement of atoms or molecules.

Isometric System

A crystal system with three axes of equal length that are all perpendicular to each other ($a=b=c$; $a\perp b\perp c$).

Monoclinic System

A crystal system with three unequal axes ($a\neq b\neq c$) where two axes are perpendicular and the third is not.

Mineralogy

The study of the origin, formation, physical and chemical properties, classification, and uses of minerals.

Idiochromatic

A classification of mineral color that remains constant, usually found in non-transparent or opaque minerals.

Luster (Kilap)

The appearance of a mineral based on the reflection of light from its surface, categorized as metallic or non-metallic.

Mohs Scale

A relative scale used to determine mineral hardness, ranging from 1 (the softest, such as Talk) to 10 (the hardest, such as Intan).

Streak (Cerat)

The color of a mineral in its powdered form, obtained by rubbing the mineral against a porcelain plate.

Cleavage (Belahan)

The tendency of a mineral to break along flat, smooth planes based on its internal atomic structure.

Fracture (Pecahan)

The tendency of a mineral to break along irregular or uneven surfaces rather than smooth planes.

Tenacity (Sifat dalam)

The reaction of a mineral to external stress, such as being brittle, ductile, malleable, elastic, or flexible.

Ferromagnetic

Minerals that exhibit magnetic properties and are attracted to magnets, such as magnetit.

Dana Classification

A mineral classification system based on chemical composition and crystal structure, dividing minerals into 8 major groups.

Silicates

The most abundant mineral group, containing Silicon and Oxygen bonds and making up about 25% of all known minerals.

Petrology

The branch of geology that studies rocks, including their origins, occurrences, structures, and history of formation.

Magma

A naturally occurring, hot, mobile silicate melt containing solid materials and gases; it is the parent material for igneous rocks.

Bowen's Reaction Series

A chart showing the sequence of mineral crystallization from cooling magma, consisting of continuous (plagioclase) and discontinuous branches.

Phaneritic

An igneous rock texture where crystals are large enough to be seen with the naked eye, typical of intrusive rocks.

Aphanitic

An igneous rock texture where crystals are too small to be distinguished by the naked eye, typical of extrusive rocks.

Porphyritic

An igneous rock texture consisting of large crystals (phenocrysts) embedded in a matrix of smaller crystals (groundmass).

Vesicular

An igneous rock structure characterized by small cavities or holes formed by trapped gas bubbles, such as in pumice or scoria.

Dike (Korok)

A discordant, sheet-like intrusive igneous body that cuts across existing rock layers.

Batholith

A very large intrusive igneous body with an exposed surface area of thousands of square kilometers.