3.Lecture Pengantar GT TSL Batuan Metamorf-WK5

8/19/2019 3.Lecture Pengantar GT TSL Batuan Metamorf-WK5

1/25

PENGANTAR

(TSL)

I Gde Budi Indrawan, Ph.D.

ma : g n rawan.ugm gma .com


2/25

V. BATUAN - Pengertian

Batuan

.

2Jurusan Teknik Geologi | Universitas Gadjah Mada


3/25

V. BATUAN - Batuan Metamorf

Metamorfisme

yang berbeda.

• Jenis- enis:

1. Metamorfisme termal (sentuh)

2. Metamorfisme dinamik (tekan)

3. Metamorfisme regional



4/25


1. Metamorfisme termal (sentuh)

.

• Terjadi pada jalur magma yang menerobos batuan lain.

.



5/25


2. Metamorfisme dinamik

.

• Terjadi pada daerah yang mengalami tektonik yang

men hasilkan retakan dan atahan sesar .

• Bersifat lokal.



6/25


3. Metamorfisme regional

.

• Terjadi pada daerah dekat tumbukan lempeng.

.



7/25


Tanda-tanda metamorfisme

• en e orme ayers

Shale

7Jurusan Teknik Geologi | Universitas Gadjah Mada Gneiss


8/25


• Flattened rock fragments

Conglomerate


Metaconglomerate


9/25


• Minerals tightly interlocked due to recrystallization under

Quartz Sandstone

Quartzite



10/25


• New mineral assemblages

Shale: Clay minerals

Metamor hism

(Mid-grade)

Schist: Mica, Feldspar and

o er s ca e m nera s



11/25


Proses metamorfisme

• aren roc

– Even though original

elements are provided by

parent rock, except water

Shale

11Jurusan Teknik Geologi | Universitas Gadjah MadaSchist


12/25


• Increased Temperature (geothermal gradients)

–

minerals stable at higher temperatures Temp.

(ºC)

B

A B C



13/25


• Increased Pressure (and stress)

–

– Compression at convergent plate boundary or – Sheared as plates slide past each other



14/25


•

– Water (and other fluids) within rocks and minerals

– Moving during metamorphism

– Accelerates solid-state chemical reactions and – May change rock composition

• Time Millions of ears!



15/25


Batuan metamorf

batuan ubahan

• Berfoliasi

» Semacam erla isan ada

batuan sedimen namun

tersusun atas mineral-mineral.Schist (foliated) (http://www.snyder.shp.org/)

•


Quartzite (non foliated)


16/25



Contoh pembentukan foliasi pada batuan metamorf (Lutgens et al., 2012)


17/25


• Macam-macam foliasi:

−

» Foliasi mineral-mineral berbutir sangat halus (lempung)

sehin a men eru ai lem en -lem en an teratur dan

mudah dibelah searah dengan lempeng tersebut.

−Skistosik» Foliasi yang ditunjukkan oleh susunan mineral-mineral

pipih, misalnya mika.

−

» Foliasi yang ditunjukkan oleh deretan mineral berbutir

kasar umumn a beru a mineral felds ar dan kwarsa.



18/25




19/25


Contoh Proses Metamorfisme

1. Parent rock: Shale

– Minerals stable under low T& P

(atmospheric): clay (and quartz)

– Compaction due to accumulation of sediment

– Water bound in crystalline structure of clay

2. Low- rade metamor hism: Slate

– Minerals stable under low-grade metamorphic

conditions: fine grained mica (and chlorite and

quartz)

– Slaty Cleavage due to realignment of platyminerals

– Water is expelled from crystalline structure of

Jurusan Teknik Geologi | Universitas Gadjah Mada

c ay

19


20/25


3. Medium-grade metamorphism: Phillite

– Medium-grade metamorphic T& P causes

minerals to grow

– Minerals stable under medium-grade

metamorphic conditions: coarser grained

– Slaty cleavage becomes rippled and rock has

a sheen

4. Medium to high-grade metamorphism :

Schist

–needle like minerals

– Minerals stable under medium to high-grademetamorphic conditions: coarser grained

Jurusan Teknik Geologi | Universitas Gadjah Mada

mica and quartz

20


21/25


5. High-grade metamorphism: Gneiss

– High-grade metamorphic T& P causes

minerals to separate into bands

– Minerals stable under high-grademetamorphic conditions: feldspar

–minerals

. -

partial melting: Migmatite

– Silica rich minerals melt first (quartz and

felds ar to form silicic ma ma

– Injected into fractures resulting in silicic veins

if intrusive igneous rock

Jurusan Teknik Geologi | Universitas Gadjah Mada 21


22/25


Metamorphism of other parent rocks into non-foliated

metamorphic rocks

Quartz Sandstone

Quartzite



23/25


Asal batuan metamorf

BATUAN ASAL BATUAN METAMORF

Batuan beku, endapan, piroklastik, dan

batuan metamorf berbutir kasar,

Gneis (gneiss)

misalnya granit, konglomerat, breksi.


batuan metamorf berbutir sedang-halus,

Sekis (schist)

m sa nya asa , a u pas r, u .


batuan metamorf berbutir halus-sangat

Batu sabak (slate)

, , ,

lempung.

Batugamping, dolomit Marmer (marble)

Batu asir kwarsa Kwarsit uartzite

Jurusan Teknik Geologi | Universitas Gadjah Mada23


24/25


Klasifikasi batuan metamorf



25/25


Klasifikasi batuan metamorf


Lutgens et al. (2012)

3.Lecture Pengantar GT TSL Batuan Metamorf-WK5

Documents

Transcript of 3.Lecture Pengantar GT TSL Batuan Metamorf-WK5