Petrology (Done) Flashcards
These are naturally occurring solid substances which are aggregates of minerals
Rocks
The ___________ and _________ affect the texture which reflects how the rock was formed.
Configuration and composition
This refers to the web of processes that outline the major rock classifications form and breakdown on the different application of heat and pressure.
Rock Cycle
The type(s) of energy required for rock cycle to occur.
Solar Energy (mainly for sedimentary rocks)
Earth’s Internal Engine (igneous and metamorphic rocks)
It is concerned with rocks that are made up of definite mineral assemblages.
Petrology
It is a descriptive study on the rock n its textural, mineralogical, and chemical parts.
Petrography
It is the study on the general characteristics of rocks and employs knowledge from field exposures or hard specimens.
Lithography
It deals with the origin of rocks.
Petrogenesis
It is the study on the flow of mantle
Rheology
It is a molten rock lighter than the surrounding rocks and works upward to reach the surface.
Magma
Most magma are concentrated within ______ while they are less found along ______.
divergent zones and convergent zones
It is the liquid component of the magma which is made up of mobile ions of the abundant elements.
Melt
It is the crystallized silicate minerals from the melt
Solid Component of the Magma
These are mainly water vapor, carbon dioxide, and sulfur dioxide which are vaporized at the surface pressures since these gases were confined at extreme subsurface pressures.
Volatiles
A molten rock where all of its volatiles escaped and have reached the surface.
Lava
_________ breaks down the ions which were arranged in a fixed manner. The atoms vibrate due to heat resulting to ions occupying spaces and expanding.
Increase in temperature
The faster the vibration, the ions break away from their rigid configuration allowing ______ to occur.
Melting
This allows the ions to migrate to join existing crystalline structures thus creating larger crystals.
Slow Cooling
This is the increase of temperature with depth in the Earth
Geothermal Gradient
Geothermal Gradient is about:
25 degrees per kilometer at the first 3-5kms
It refers to the increase in temperature allowing melting to happen. It is governed by geothermal gradient which triggers melting.
Heat Transfer Melting
Fluctuations in subsurface pressures decreases the rock’s melting point as the material is carried to an environment different from what was suitable to its former configuration.
Decompression Melting
Increase in confining pressure causes increase in rock’s melting temperature making the material ________
Compact or less voluminous
Decompression melting occurs in:
Zones of upwelling and hotspots
Water content affects melting which causes rocks to melt at lower temperatures thus it determines whether the rock exists either solid or liquid.
Flux Melting
Deeply buried “wet” rock has much _____ melting temperature than the dry rock of the same composition. Since the addition of water makes rock more buoyant allowing it to rise and disrupt its chemical bonding.
Lower
This happens when the earlier-formed minerals are denser than the liquid portion of the melt and thus sink down to the magma chamber.
Crystal Settling
This happens when one or secondary magma is formed from a single magma.
Magmatic Differentiation
The compositions change through the contamination of foreign material such as those of the surrounding rock.
Assimilation
This happens in the ascent of 2 chemically distinct magma bodies as the more buoyant mass overtakes the more slowly mass.
Magma Mixing
It is the incomplete melting of rock where it produces the most magma. These contain a melt of rocks with various melting temperatures along with a melt made of low temperature minerals
Partial Melting
Most magmas generated by partial melting are closer to _________ in composition.
Felsic
This describes the temperature at which minerals crystallize when cooled, or melt when heated. The low end of the temperature scale where all minerals crystallize into solid rock is approximately 700°C.
Bowen’s Reaction Series
These are mafic/ iron-bearing that react discontinuously to form a next mineral in the series by decreasing temperatures.
Discontinuous Series
It represents the enrichment of Calcium to Sodium then to Potassium in Plagioclase Felspars with decreasing temperatures.
Continuous Series
This is a method of predicting the relative stability or weathering rate of igneous minerals once they are subjected to environments different from their formation.
Goldich Dissolution Series
Composition, Temperature, and the Number of Dissolved Gases
Factors in measuring volcanic activity
Magma associated with explosive eruption is ______ more viscous than a flowing magma.
5 times
The flow of magma is slowed when silicate structures start _____________
Polymerization
_____________ means more gas bubbles making magma more viscous and explosive.
Increase in water and gas content
The dissolved water in magma ____________ fluidity and ____________ polymerization.
Increases and decreases
Felsic magma explodes ________ due to the loss of the confining pressure to hold gases until the magma chamber is emptied.
in a series of eruptions
These eruptions contain gases of about 70% water vapor, 15% carbon dioxide, 5% nitrogen, and 5% sulfur dioxide with trace amounts of chlorine, hydrogen, and argon.
Hawaiian-Type Eruptions
These are flows of jagged blocks with sharp edges and spiny projections
Aa flows
these ae smooth, fluid surfaces like those of twisted ropes and end to form in much higher temperatures.
Pahoehoe Flows
These are hardened basaltic flows which contains cave-like tunnels that were once conduits.
Lava Tubes
These are felsic-intermediate magmas that generate short prominent flows which consists of vesicle-free detached blocks.
Block Lavas
These are pillow-shaped structures attributed to the extrusion of lava underwater or in subaqueous extrusion.
Pillow Lavas
These are low-viscosity basaltic magmas that produces fire fountains. These are generally non-explosive and produce very little pyroclastic emission.
Hawaiian Type Eruption
Distinct blasts of basaltic to andesitic magmas which produces incandescent bombs building smaller cinder cones. These are mildly explosive and produce a low elevation eruption columns and pyroclastic fall deposits.
Strombolian Eruption
These are sustained explosions of solidified or highly viscous andesite-rhyolite magma from the vent. These make widespread pyroclastic falls and are very explosive.
Vulcanian Explosion
A collapse of an andesitic or rhyolitic lava dome with or without a directed blast which produces Nuee Ardentes and known for being explosive.
Pelean Explosion
A sustained injection of andesitic-rhyolitic magma 45km from the vent and exhibits eruption collapse to produce pyroclastic flows and surges. Its ash cloud can circle the Earth thus they are violently explosive.
Plinian Explosion
This happens when a magma encounters a shallow groundwater and flashing it to steam. However, no new magma reaches the surface.
Phreatic Eruption
This happens when magma comes into contact with a shallow groundwater using a flash of steam which is ejected along with pre-existing fragments of the rock and tephra from magma. It less explosive than a Plinian eruption.
Phreatomagmatic Eruption
This happens when magma comes into contact with a shallow groundwater using a flash of steam which is ejected along with pre-existing fragments of the rock and tephra from magma. It less explosive than a Plinian eruption.
Phreatomagmatic Eruption
Effusive (Hawaiian)
0 Rank < 104 m3 (E.g. Kilauea-current)
Gentle (Hawaiian / Strombolian)
1 Rank > 104 m3 (E.g. Mt. Mayon -2006)
Explosive (Strombolian / Vulcanian)
2 Rank > 106 m3 (E.g. White Island-2019)
Severe (Strombolian / Vulcanian / Peléan / Sub-Plinian)
3 Rank > 107 m3 (E.g. Mt. Mayon -2001)
Catastrophic (Peléan / Plinian / Sub-Plinian)
4 Rank > 0.1 km3 (E.g. Taal- 2020)
Cataclysmic (Peléan / Plinian)
5 Rank > 1 km3 (E.g. Mt. St. Helens -1980)
Colossal (Plinian / Ultra-Plinian)
6 Rank > 10 km3 (E.g. Mt. Pinatubo- 1991)
Super-Colossal (Ultra-Plinian)
7 Rank > 100 km3 (E.g. Tambora- 1815)
Mega-Colossal (Ultra-Plinian)
8 Rank > 1,000 km3 (E.g. Yellowstone -640K years ago)
This refers to a pyroclastic material with a diameter greater than 64mm and angular fragments.
Blocks
These are pyroclastic materials with size 2-64mm size.
Lapilli
These are pyroclastic materials greater than 64mm size.
Lava Bombs/ Volcanic Bombs
It is the world’s largest caldera with a size of 150km diameter. It is made up of 9 mile thick layer of volcanic rocks from 47.9-26 Million years ago.
Apolaki Caldera in the Benham Rise
Flux Melting is much more common in _____________ due to subduction.
Convergent Boundaries
These are constructed in between oceanic or between continental plates which give rise to volcanic islands.
Volcanic Island Arcs
These are constructed between oceanic to continental plates with the same mechanism with the volcanic arcs only that its is introduced to areas rich with silica.
Continental Volcanic Arcs
This forms volcanoes due to partial melting and decompression melting which then produces basaltic magma rising in the surface. It contributes to about 60% of magma output.
Divergent Boundaries
These occur in hotspots generated by mantle plume. These ascend to the surface forming flood basalts forming volcanic islands.
Intraplate Volcanism
Siberian and Deccan Traps were probably created by a mantle plume having a very ________ head and a very ______ tail.
Large, Long
These are structures formed from the emplacement of magma.
Plutons
These are produced when magma is forcibly injected into zones of weaknesses (i.e. fractures)
Tabular Intrusive Bodies
These are plutons formed from cutting across the structure.
Discordant
These are discordant sheet-like bodies that serve as conduits that transport magma and manifest as weathering resistant walls once exposed at the surface.
Dikes
These are roughly parallel groups branching from a single dike.
Dike Swarms
These are plutons that are placed parallel to structures.
Concordant
These are concordant sheet-like bodies that store magma. Once cooled and exposed to the surface, these manifest by columnar jointing.
Sills
These are large intrusive bodies with 100 sq.km in size composed of felsic-intermediate rocks.
(Granite) Batholiths
These are igneous intrusions with size lesser than that of a batholith
Stocks
A viscous sill with a dome-shaped structure forcibly injected between sedimentary strata giving a mushroom like appearance.
Laccolith
These are produced by the accumulation of fluid basaltic lavas with a prominent dome structure. These start off as seamounts eventually forming volcanic islands
Shield Volcanoes
Steep sided structures built from ejected lava fragments that take on the appearance of clinkers as they begin to harden in flight.
Cinder Cones/ Scoria Cones
These are manifestations of plate tectonics especially along subduction zones. It is formed from gas-rich magma having an andesitic composition and are known to generate an explosive eruption ejecting huge quantities of pyroclastic material.
Stratovolcano/ Composite Volcanoes
A hollow within a volcano where magma and gases settle.
Magma Chamber
A pipe-like passageway where magma and gases escape.
Conduit
_____________ work by expanding the fractures along the sides of the wall then eroding it forming conduits.
High Pressure Gases
The opening on the surface of a volcano that emits lava, gases, ash, or other Volcanic material
Vent
These are formed when explosive eruptions occur.
Crater
These are cone-shaped accumulations of volcanic material not part of the central vent.
Parasitic Cones
These are parasitic cones that only eject gases.
Fumaroles
Circular depressions greater than 1km that emits lava, gases, ash or other volcanic materials. These are produced after an explosive eruption which only lasts for a few hours to few days.
Caldera
This is formed where a collapse of the summit from a silica-rich pumice and ash.
Crater-lake Type
The collapse of the top of a shield volcano. This is due to subsidence as magma is drained laterally from the underlying magma chamber.
Hawaiian Type
The collapse of a large area caused by a discharge of colossal volumes of silica rich pumice and ash along ring fractures.
Yellowstone Type
These are spots where lava emerges in the ground rather in the form of a volcanic cone or a vent
Fissures
A giant volcanic eruption resulting to large stretches of land or ocean floor filled with basaltic lava.
Flood Basalts
A mound shaped protrusion resulting to slow extrusion of viscous lava from volcanoes.
Lava Dome
Felsic lava given that they hardly flow at all produces lava domes of ____________ in height, forming in flanks or summits of composite volcanoes.
10m - 1km
A channel bored through the crust allowing molten magma chamber to travel up and out during volcanic eruption.
Volcanic Pipe
These are formed from the congelation of magma or consolidation of volcanic breccia in the conduit and may be exposed by weathering
Volcanic Necks/ Volcanic Plugs
This is where magmas migrate upward and travel rapidly enough that they go little alteration during ascent. These run up to 200kms in depth.
Diatremes
These are turbulent, fast-moving cloud of hot gas and ash erupted as columns of material collapse.
Nuee Ardentes
These are powerful hot blasts that carry small amounts of ash that separate from the body of flow.
Surges
The crystallization of magma is dependent on the following factors:
(1) Rate of Cooling
(2) Silica Content
(3) Amount of Dissolved Gases Present
These are formed at subsurface conditions. Coarse-grained containing visible crystals.
Intrusive Igneous Rocks/ Plutonic Igneous Rocks
These are formed when molten rocks are solidified at the surface. These are fine-grained and may form from any volcanic debris.
Extrusive Igneous Rocks/ Volcanic Igneous Rocks
Igneous Rocks are classified based on __________ and _________
Texture and Composition
It is formed at the surface or in small intrusive masses within the crust where it is a product of rapid cooling. It exhibits light to dark color and are equally fine-grained.
Aphanitic Texture
These are mainly extrusive rocks that contain voids left by gases. These are formed from the upper zone of the lava flow.
Vesicular Texture
This is formed when large masses of magma cool at a great depth, creating a mass of intergrown crystals roughly equal in size and are large. These are equally coarse-grained.
Phaneritic Texture
This forms when magma crystallizes below the volcano allowing crystallization to occur but due to changing conditions, some minerals are cooled before completing crystallization.
Porphyritic Texture
This refers to the large crystals in rocks with porphyritic texture.
Phenocrysts
