Post on 24-Dec-2015
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PRIMARY MINERAL SEQUENCE
McClelland’s Weathering Sequence
Bowen’s Reaction Series
olivine
pyroxene
amphibole
biotite
calcium - rich
plagioclase
sodium - rich
orthoclase ( k-rich )
muscovite
quartz 800 ° C
1400 °Cmafic (basic)
intermediate
felsic (acidic)
Discontinuous B
ranch
Con
tinuo
us B
ranc
h
( orthoclase )
Less resistant
More resistant
PRIMARY MINERAL SEQUENCE
McClelland’s Weathering Sequence
Bowen’s Reaction Series
olivine
pyroxene
amphibole
biotite
calcium - rich
plagioclase
sodium - rich
orthoclase ( k-rich )
muscovite
quartz 800 ° C
1400 °Cmafic (basic)
intermediate
felsic (acidic)
Discontinuous B
ranch
Con
tinuo
us B
ranc
h
( orthoclase )andesite
dacite
rhyolite
Less resistant
Moreresistant
Acidic Intermediate Mafic
Coarse : granite monzonite gabbro
Medium : (--) porphyry (--) porphyry diabase
Fine : rhyolite latite andesite (Na), basalt (Ca)
Potasium (K) Feldspar
APHANITIC
IGNEOUS ROCKS CHART
KEY MINERAL COMPOSITIONAcidic Intermediate Basic Ultrabasic
( - - - ) ( ultramafic)Potasium (K) Feldspar & Plagioclase (Na, Ca) Feldspar
Pyroxene
CRYSTALLINETEXTURE
> 2/3 of Total Plagioclase (Na, Ca) Feldspar > 2/3 of Total andFeldspar Content in about equal proportions Feldspar Content Olivine
Sodic (Na) Calcic (Ca) Plagioclase Plagioclase
PEGMATITIC Quartz No Quartz Quartz No Quartz Quartz No Quartz( very coarse, uneven-sized crystal grains )
granite pegmatite
syenite pegmatite
monzonite-pegmatite
diorite pegmatite
gabbro pegmatite
peridotite (mostly olivine)
PHANERITIC
( crystals visible and of nearly equal size )
granite syenitequartz
monzonitemonzonite
quartz-diorite
granodioritediorite gabbro
pyroxenite (mostly
pyroxene)
PORPHYRITIC
( relatively few visible
granite porphyry
syenite porphyry
quartz- monzonite porphyry
monzonite porphyry
quartz-diorite
porphyry
diorite porphyry diabase
crystals within a fine-grained matrix ) rhyolite
porphyrytrachyte porphyry
quartz-latite porphyry
latite porphyry
dacite porphyry
andesite porphyry
porphyry basalt
( crystals visible only
with magnifation )
micro.1 crypto.2
rhyolite trachytequartz latite
latite dacite andesite basalt } lava 3
obsidian (and its varieties: perlite, 1 Microcrystalline - crystals visible with ordinaryGLASSY
pitchstone, pumice, scoria) magnification (hand lens, simple microscope).( amorphous: no 2 Cryptocrystalline - crystals only visible with SEM
crystalline structure ) pyroclastics are shown on the Sedimentary 3 Lava - generic name for extrusive flows of and Volcaniclastic Rocks chart. non-clastic, aphanitic rocks (rhyolite, andesite, basalt)
( mafic)( Felsic)
p. 5-4, Field Book …, 2002
vesicular basalt (in lava flow) Kilbourne Hole, NM
Schoeneberger
rhyolite from Organ Mtns, NM
Schoeneberger