Download - Igneous Rock Clan2
-
8/13/2019 Igneous Rock Clan2
1/23
3. Lamprophyres and
Ultrabasic RocksA. Lamprophyre
B.Melilite-rich rocks
C. Carbonatites
D. Kimberlite
E. Peridotite
-
8/13/2019 Igneous Rock Clan2
2/23
A. Lamprophyre
Lamprophyre : merupakan istilah yangdigunakan untuk menyebut suatu kelompok
batuan beku basic-ultrabasic, berwarna
gelap, yang pada umumnya terbentuk pada
dyke dangkal. Umumnya kaya akan unsur
alkali dan ferro-magnesian.Ciri utamanyaadalah tekstur, dimana sebagian besar
lamprophyre bertekstur porfiritik
(fenokris biotit, amphibole, augit dan
groundmass feldspar). Baik fenokris maupun
groundmass berbentuk euhedral (olehbeberapa ahli disebut tekstur
panidiomorfik).
-
8/13/2019 Igneous Rock Clan2
3/23
-
8/13/2019 Igneous Rock Clan2
4/23
Ada 2 kelompok lamprophyre :
a. Calcalkaline(biotite andhornblenda lamprophyre)
b. Alkaline (ultrabasic lamprophyre)
a. CALKALKALINE- SiO2 content : 50%-54%
- Colour Index : 35-50
- Mineralogi : biotite, green-brown
hornblende, diopsidic augite,feldspar, with or without quartzor altered olivine.
-
8/13/2019 Igneous Rock Clan2
5/23
Anggota :
i. Biotite lamprophyre
=>minette (rich K Feldspar),
kersantite (rich plagioklas)
ii. Hornblende lamprophyre
=>vogesite (rich K feldspar)
spessartite (rich plagioclas)
-
8/13/2019 Igneous Rock Clan2
6/23
b. Alkalinelamprophyre
- SiO2 content : 38-42%
- Mineralogi : titaniferous augit, brown
alkaline amphibole. Olivin + biotit sering
hadir sebagai fenokris.
- Anggota :
i : camptonite (groundmass : plagioclase)ii: monchiquites (groundmass :glass)
-
8/13/2019 Igneous Rock Clan2
7/23
B. MELILITIC ROCK
i. Alnoites
- SiO2 content :
-
8/13/2019 Igneous Rock Clan2
8/23
C. CARBONATITES
- Merupakan batuan beku yang terutama tersusunoleh carbonat (calcite, dolomite, ankerite)
- Tekstur dan kenampakan umum, mirip dengan
marble.- Umumnya terbentuk sebagai central plugs dan
irregular dyke in eroded volcanic center.
- Asosiasi : with basic or ultrabasic alkaline rock
(ijolite and alkaline pyroxenite)- Mineralogi : calcite, dolomite, ankerite, with
biotite, olivine, alkali feldspar, sodic pyroxene
-
8/13/2019 Igneous Rock Clan2
9/23
-
8/13/2019 Igneous Rock Clan2
10/23
carbonatite
-
8/13/2019 Igneous Rock Clan2
11/23
D. Kimberlites
-
8/13/2019 Igneous Rock Clan2
12/23
Kimberlite is a gas-rich, potassic ultramaficigneous rock that contains the minerals
olivine, phlogopite, diopside, serpentine,calcite, and minor amounts of apatite,magnetite, chromite, garnet, diamond, and
other upper mantleminerals. Uppermantle xenoliths are found in somekimberlite and provide clues to themagma's origin. The source depth for
kimberlite magmas is estimated at 200 km,more than twice as deep as the sourceregion for most magmas.
http://volcano.und.edu/vwdocs/vwlessons/plate_tectonics/part13.htmlhttp://volcano.und.edu/vwdocs/vwlessons/plate_tectonics/part13.html -
8/13/2019 Igneous Rock Clan2
13/23
At a depth of 200 km the pressure is 60,000times greater than the surface and thetemperature is about 1500 C. Kimberlitemagmas are rich in carbon dioxide and waterwhich brings the magma quickly and violently tothe surface. Most kimberlites occur as multipleintrusive events. Kimberlite was named for therock associated with diamonds in Kimberley,
South Africa. kimberlite erupted at a rare type of volcanic vent
called a diatreme or pipe.
-
8/13/2019 Igneous Rock Clan2
14/23
E. Peridotite and allied rock
i. Peridotite
- Umumnya bertekstur holocrystalin,
anhedral-granular, medium to coarse
grain.
- Mineralogi : olivin, pyroxene (enstatite
and diposidic augite),with plagioclase,
hornblende, biotite, garnet.
-
8/13/2019 Igneous Rock Clan2
15/23
-
8/13/2019 Igneous Rock Clan2
16/23
ii. Dunite
- Tersusun oleh olivin
-
8/13/2019 Igneous Rock Clan2
17/23
iii. Pyroxene peridotit
- Wehrlite : olivine and diposidic augite (3:1)assesori : enstatite, picotite, chromite,hornblende
- Harzburgite : magnesian olivine and
orthopyroxene (enstatite, bronzite). Asesori :chromite, iron-titanium oxide, diopsidic augit,calcic plagioclas
- Lherzolite :Lherzolites contain over 60% olivine,
and some clinopyroxene and orthopyroxene.Lherzolite is a major constituent of the mantleand the source of most basaltic magmas.
-
8/13/2019 Igneous Rock Clan2
18/23
lherzolite
OL
OPx
CPx
-
8/13/2019 Igneous Rock Clan2
19/23
iv. Hornblende peridotite
v. Garnet peridotitevi. Mica peridotite
vii. Plagioclas peridotit
viii.Komatiites
-
8/13/2019 Igneous Rock Clan2
20/23
4. FELDSPATHOIDAL FELSIC
ROCK
A. Volcanic Division : Phonolite Family
It consists mainly of nepheline and alkali feldspar
(sanidine or anorthoclase).
Other minerals occuring in phonolite are soda-pyroxenes, soda-amphiboles,
leucite, alcime and sodalite-group minerals (sodalite,
nosean, hauyne). It is the volcanic equivalent of
nepheline syenite.
-
8/13/2019 Igneous Rock Clan2
21/23
-
8/13/2019 Igneous Rock Clan2
22/23
B. Plutonic Division : FeldspathoidalSyenite family
- Intermediate SiO2 content
- Alkali feldspar & feldspathoid sebagaipenyusun utama
- Kaya unsur sodium (dalam feldspathoid
berupa nephelin, analcime, sodalite,nosean, dalam sodic feldspar, dan maficmineral :augit, aegirin)
-
8/13/2019 Igneous Rock Clan2
23/23
syenite
Plg
Px
Bi
Ne