PETROGRAFIBatuan & Struktur Bumi

Batuan & Struktur BumiThe Earth’s InteriorThe crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks. The crust is underlain by the mantle. The upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust.

The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity. Earth's crust occupies less than 1% of Earth's volume

The Earth’s Interior

Kerak Samudera (Oceanic Crust)• Kerak samudra membentuk 65% permukaan bumi, mempunyai ketebalan

antara 5-10 km, dan berkomposisi basalt, diabas dan gabro. • The oceanic crust sometimes called SiMa (Silicate Magnesium) • Seri batuan kerak samudra dan mantel atas, bersama dengan batuan sedimen

laut disebut Ofiolit.

Kerak bumi (Crust) terbagi menjadi :1. Kerak Samudera

(Oceanic Crust)2. Kerak Benua

(Continental Crust)

OfiolitKomposisi tipikal seri ofiolit (dari bawah ke atas):• Hazburgit, dunit, peridotit dan piroxenit,

mencerminkan bagian atas dari mantel samudra. Biasanya batuan-batuan ini teralterasi menjadi serpentinit,

• Gabro, berkandungan besi-titanium dan magnesium, berlapis, dan di bagian atas terdapat gabro masif yang berasosiasi dengan plagiogranit,

• Sheeted dyke gabbro,• Basalt berstruktur bantal (pillow basalt), lava

yang mengalir dilantai samudra. Berstruktur bantal mencerminkan pembekuan yang cepat karena bersentuhan dengan air laut,

• Sedimen laut, radiolarian chert dan batugamping, batupasir graywacke dan batulempung, atau batuan metamorf-nya, marmer, quartzite dan sekis mika.

The Earth’s Interior

Kerak Benua (Continental Crust)• The continental crust is typically from 30 km (20 mi) to 50 km

(30 mi) thick, and is mostly composed of granite.• The continental crust sometimes called Si-Al (Silicate-

Alumunium)

The Earth’s InteriorMantle:Peridotite (ultramafic)Upper to 410 km (olivine ® spinel)

Low Velocity Layer 60-220 km

Transition Zone as velocity increases ~ rapidly Spinel ® perovskite-type

Lower Mantle has more gradual velocity increase

Core: Fe-Ni metallic alloy

Outer Core is liquid No S-waves

Inner Core is solid

Plate Tectonic - Igneous Genesis

1. Mid-ocean Ridges2. Intra-continental Rifts3. Island Arcs4. Active Continental Margins 5. Back-arc Basins6. Ocean Island Basalts7. Miscellaneous Intra-Continental Activity (kimberlites, carbonatites,

anorthosites)

Environments of Magma Formation

Keterdapatan Dan Penyebaran Batuan

Berikutnya..Tinjauan Petrologi