IGNEOUS PETROLOGY (PYROCLASTICS) Flashcards
Literal meaning of pyroclastic
Fiery Fragments
An individual material/particle ejected during volcanic eruption
Pyrcoclast
Any rock consists of unreworked solid material of whatever size explosively or serially ejected from a volcanic vent
Pyroclastic Rock/Tephra
Formed if the outside of the bomb solidify during their flight and develop cracked surface and the interiors continue to expand
Breadcrust Bombs
Rock Fragments formed from ejected droplet of Magma
Lapilli
Small spherical balls of volcanic ash that form a wet nucleus falling though a volcanic ash cloud. They can flatten on hitting the ground or may roll on loose ash and grow like a snowball
Accretionary Lapilli
All Fresh Volcanic ejecta including GLASS and Minerals coming directly from the magma involved
Essential or Juvenile
Solid fragments of volacanic rock derived from the conduit or crater walls and eruptive column
Accessory
Solid chips from the subvolcanic basement wether igneous, sed or met
Accidental
Injection to the atmosphere followed by fallout
Pyroclastic Fall
Ground Hugging , relatively high particle concentration
Pyroclastic Flow
Relatively low particle concentration and usually found at the base of a eruption column
Pyroclastic Surge
?Mantle bedding with plane parallel and no internal erosion
?Well sorted
?Ragged and angular shape
Fall
?Non Mantling Beds thickening at low lying areas with cross stratificatio. Pinch and swerll bedding and scoured contacts.
?Moderately Sorted
?Juvenile Clasts with moderate rounding
surge
?Landscape Filling units, generally poorly bedded to non-bedded
?Poor Sorted
?Rounded Juvenile Clasts
Flow
