Luluhawa

Learning objectives
luluhawa
1 Apa itu
2 Bagaimana
terjadi
3 Jenis2 luluhawa
4 Faktor2 yg mempengaruhi
luluhawa
5 Impak/kesan
6 hasil
7 kepentingan

Luluhawa – suatu proses yang
berlaku di permukaan bumi untuk
memecah dan menguraikan
batuan (break and decompose
rocks)
Enviromen: terhad kepada sejauh
mana air tanah (groundwater)
boleh menusuk masuk (penetrate)
ke dalam permukaan bumi

luluhawa
 Boleh dilihat sebagai destructive forces
- yang memecah, mengurai, mengubah
bentuk dan keadaan fizikal dan kimia batuan
 Boleh dilihat sebagai constructive forces –
yang menghasilkan sedimen, membentuk
batuan mendak, mineral, mendapan
mineral, landform baru

Fakta asas luluhawa
 Berlaku perlahan sepanjang masa
 Mengambil masa yang lama
 Semua jenis luluhawa berlaku kadang2
serentak dan tak terpisah satu sama lain.
Dipisahkan untuk memudahkan
pemahaman sahaja
 Keadaan di keliling menentukan segalanya

Jenis2 luluhawa
1. Luluhawa fizikal
2. Luluhawa kimia
3. Luluhawa biologi

1. Luluhawa fizikal
 Memecahkan batuan yang bersaiz besar kepada
bahagian yang lebih kecil
contoh: wedging (pembajian), exfoliation
(pengelupasan), thermal expansion (kembang
haba), lelasan (abrasion), (wetting and drying (esp
in shales), pressure release by erosion of
overburden

Luluhawa fizikal
1 Frost wedging (pembajian ibun) – water
expands when it freezes, breaking rocks
into angular fragments; lazim berlaku
dalam iklim temperat (ada ais)
Nota: apabila air menjadi ais, isipadu
meningkat sebanyak 10% => mebungkah
(pries) batuan

talus – terdapat di kaki bukit

Luluhawa fizikal
2 Exfoliation (pengelupasan) – bedrocks
(batuan hampar) breaks into flat sheets
along joints (kekar) which parallel the
ground surface. This phenomenon is
caused by expansion of rock when the
pressure of overlying rock is removed by
erosion => sometimes called unloading
Apa itu kekar?

Luluhawa fizikal
3 Thermal expansion (kembang haba) – heat
causes action; cooling causes contraction
=> expand and contract at different rate
causes stresses along mineral boundaries.
Repeated heating and cooling => batuan
pecah

4 Lelasan (abrasion)
 Batuan menjadi lebih kecil hasi drpd
pergeseran dan pelanggaran semasa
terangkut, contohnya di dasar sungai
 Glasial, ombak dan angin juga boleh
menjadi agen lelasan

Kelebihan kimia fizikal
 Luluhawa fizikal memecahkan batuan ke
saiz yg lebih kecil => menyediakan lebih
banyak luas permukaan batuan bersaiz
kecil untuk tindakbalas kimia berlaku

2. Luluhawa kimia
 Memecahkan batuan secara kimia dgn
menambah atau menanggalkan (removing)
unsur2 kimia, mengubah unsur2 tersebut
menjadi bahan2 baru
contoh: dissolution (pelarutan), hydrolysis
(hidrolisis), oxidation (pengoksidaan)

Luluhawa kimia
1 Dissollution (pelarutan) – alters rocks by
removing soluble minerals => soluble ions
and insoluble ions => precipitate and
crystallize (dalam tasik atau laut)
Ex: pembentukan garam, batu
kapur, travertine
Batuan => ion larut/ tak larut => pemendakan

Luluhawa kimia
2 Hydrolisis – proses di mana feldspar are
weathered to form clay
Note: clay make up half of sedimentary
rocks on Earth
(Berapa jenis feldspar kita ada? Apakah
komposisinya?)

Beberapa contoh t/b kimia
A. Solution of carbon dioxide in water to form
acid
CO2 + H2O H2CO3 H+ + HCO3
-
B. Solution of calcite
CaCO3 + CO2 + H2O Ca2+ + 2HCO3
-
C. CaCO3 + H+ HCO3
- Ca2+ + 2HCO3
-

D. Chemical weathering of feldspar to form
clay mineral
2KAlSi3O8 + 2H+ + 2HCO3
- + H2O
K feldspar
Al2Si2O5(OH)4 + 2K+ + 2HCO3
- + 4SiO2
clay mineral Silica in solution
or as fine solid
particles

2KAlSi3O8
Al2Si2O5(OH)4
K2O
Al2O3
6SiO2
Al2O3
2SiO2
2H2O
Cara mengungkap formula untuk
memudahkan kefahaman

Luluhawa kimia
3 oxidation – the process by which iron-
bearing minerals
(pyroxene, amphibole, biotite) weather to
produce iron oxides
Di kawasan tropik iron bearing
aluminosilicate => lateritic soils, red clayey
soils

Oxidation reaction
4FeSiO3 + O2 +10H2O 4FeO.OH +
4H4SiO4
2Fe2SiO4 + 2O2 + 4H2O 4FeO.OH +
2H4SiO4
Fe pyroxene
Fe olivine
Goetite

3. Luluhawa biologi
 Pemecahan batuan disebabkan oleh
tindakan organisma hidup spt
tumbuh2an, haiwan dalam tanah dan lichen
(kulat? yang hidup di atas batuan dan kayu)

 Average daily temperatures range from a
minimum of 25o C to a maximum of 33o C.
 has an average annual rainfall of more
than 2500 mm
Malaysia

Mineral stability in the weathering
environment
Mineral didapati tak stabil dalam enviromen
tertentu
Minerals which formed at high temperature
and pressures are least stable in the
weathering environment and weather most
quickly
Minerals which formed at lower temperatures
and pressures are most stable under
weathering conditions

Soil profile
D horizon
Fresh rocks

Soil profile
Eluviation
illuviation
leaching

 Leaching/larutlesap: proses kimia yang
menghasilkan unsur larut dan tak larut.
Yang larut akan lesap ke bawah dalam
profil tanah sementara yang tak larut akan
terkumpul di bahagian atas profil tanah =>
warna membezakan lapisan tanah
 Eluviation: removal of materials dissolved
or suspended in water
 Illuviation: horizon of maximum
accumulation of suspended material or
clay
 Chelation: pembentukan kompleks kimia

Gred luluhawa (weathering grade), kekuatan
ekapaksi dan rock-soil ratio
UCS(MPa) RSR
Gred VI tanah/soil
Gred V completely weathered <0.15 0-30
Gred IV highly weathered 0.2-0.15 30-60
Gred III moderately weathered 0.4-0.2 60-90
Gred II slightly weathered 0.9-0.4 90-95
Gred I Fresh rock 95-100
Tengok transparensi lain

Sinkholes (tanah benam)
 Bagaimana terjadi?
 Enviromental problem?

Jenis2 tanah
 Residual soil - laterit, iklim tropik
 Transported soil – till, loess, iklim temperat
Tanih - pelbagai jenis tanah
contoh: laterit, pedalfer, latosol,
paleosol

Wentworth scale - grain size scale
 Particle name Particle diameter Gravel
 Boulders > 256 mm
 Cobbles 64 - 256 mm
 Pebbles 2 - 64 mm
 Granules 2 - 4 mm
 Sand
 Very coarse sand 1 - 2 mm
 Coarse sand 0.5 - 1 mm
 Medium sand 0.25 - 0.5 mm
 Fine sand 0.125 - 0.25 mm
 Very fine sand 0.0625 - 0.125 mm
 Silt 1/256 - 1/16 mm
(or 0.004 - 0.0625 mm)
 Clay < 1/256 mm
(or < 0.004 mm) sesetengah
buku guna takrif <2 mikron

Hakisan (erosion)
The movement of weathered material from
the site of weathering. Primary agent is
gravity, but gravity acts in concert with
running water
pergerakan bahan terluluhawa dari tempat
luluhawa berlaku ke tempat ia ditemui

Faktor yang mempengaruhi
pembentukan tanah
1. Iklim (climate)
2. Batuan induk (parent material)
3. Relief (keadaan permukaan bumi)
4. Vegetation (tumbuhan)
5. Masa (time)

Sambung => batuan mendak
(lihat beberapa transparensi
mengenai luluhawa)

Batuan
mendak
apa
Bagaimana
terjadi
Perubahan sebelum, semasa dan
selepas pembentukan
jenis2
kepentingan
Apa kesudahannya?
Ciri2 utama Di mana

 Sediment = loose particulate material
(clay, sand, silt, gravel, etc.)
 Sediment becomes sedimentary rock
through lithification, which involves:
 Compaction
 Cementation
 Recrystallization (of carbonate sediment)
Hasil drpd luluhawa ialah sedimen

Ternary diagram Sand-Silt-Clay

1 Terrigenous (detrital or clastic) – bumi/benua
– Conglomerate or Breccia
– Sandstone
– Siltstone
– Shale
2 Chemical/biochemical
– Evaporites
– Carbonate sedimentary rocks (limestones and dolostone)
– Siliceous sedimentary rocks
3 Organic (coals)
– Other - ironstones
Pengelasan batuan mendak

Arkose (mengandungi banyak feldspar)

Greywacke (sand-sized rock
fragments)

 Silt: Grain size 1/256 to 1/16 mm (gritty)
 Siltstone

 Clay: Grain size less than 1/256 mm
(smooth) (< 2 micron)
 Shale (if fissile)
 Claystone (if massive)
Note: Mud is technically a mixture of silt and
clay. It forms a rock called mudstone (or
mudshale if fissile).

 B. Chemical/biochemical Sedimentary
Rocks
 This group includes the evaporites, the
carbonates (limestones and
dolostone), and the siliceous rocks. These
rocks form within the depositional basin from
chemical components dissolved in the
seawater

 Evaporites - The evaporites form from the
evaporation of water (usually seawater).
 Rock salt - composed of halite (NaCl).
 Rock gypsum - composed of gypsum
(CaSO4.2H20)
 Travertine - composed of calcium
carbonate (CaCO3), and therefore, also
technically a carbonate rock; travertine
forms in caves and around hot springs.

Bonneville Salt Flats of the Great Salt Lake, Utah. The lake
bed is covered with rock salt which gives it the white color.
The salt is mined by the Morton Salt Company.

Gypsum crystals, Marion
lake, Australia

 Carbonates - The carbonate sedimentary rocks
are formed through both chemical and
biochemical processes. They include the
limestones (many types) and dolostones.
 Two minerals are dominant in carbonate rocks:
– Calcite (CaCO3) (batu kapur)-mudah berbuih
dgn asid lemah
– Dolomite (CaMg(CO3)2) – perlu digores jadi
serbuk, baru bertindakbalas dgn asid

 Carbonate rock names:
 Micrite (microcrystalline limestone) - very fine-
grained; may be light gray or tan to nearly black in
color. Made of lime mud, which is also called
calcilutite.
 Oolitic limestone (look for the sand-sized oolites)
 Fossiliferous limestone (look for various types of
fossils in a limestone matrix)
 Coquina (fossil hash cemented together; may
resemble granola)
 Chalk (made of microscopic planktonic organisms
such as coccolithophores; fizzes readily in acid)
 Crystalline limestone
 Travertine (see evaporites)
 Others - intraclastic limestone, pelleted limestone

 Siliceous rocks - The siliceous rocks are those
which are dominated by silica (SiO2). They
commonly form from silica-secreting organisms
such as diatoms, radiolarians, or some types of
sponges. Chert is formed through chemical
reactions of silica in solution replacing
limestones.
 Diatomite - looks like chalk, but does not fizz in
acid. Made of microscopic planktonic organisms
called diatoms. May also resemble kaolinite, but
is much lower in density and more porous).
Also referred to as Diatomaceous Earth.
 Chert - Massive and hard, microcrystalline
quartz. May be dark or light in color. Often
replaces limestone. Does not fizz in acid.

 . Organic Sedimentary Rocks (Coals)
 This group consists of rocks composed of organic
matter (mainly plant fragments). Because of this, they
lack minerals (which must be inorganic, be definition).
These are the coals. In order of increasing depth of
burial (temperature and pressure):
 Peat (porous mass of brownish plant fragments
resembling peat moss)
 Lignite (crumbly and black)
 Bituminous coal (dull to shiny and black; sooty;
layers may be visible)
 Anthracite coal (extremely shiny and black, may
have a slight golden shine; low density; not sooty;
technically a metamorphic rock due to high
temperatures and pressures to which it has been
subjected)

others
There are several other interesting
sedimentary rock types: Ironstones -
Oolitic hematite, banded iron formations

Abundance of sedimentary rocks

Soalan
Maklumat apakah yang boleh dicerap dari
pemerhatian batuan mendak?
Senaraikan…

 Sedimentary structures form in the basin of
deposition, as a result of the action of
natural processes such as
waves, currents, drying events, etc.
 Beds or strata
 Cross-bedding
 Graded beds
 Ripple marks
-Current ripple marks (asymmetrical ripples)
Oscillation or wave ripple marks
(symmetrical ripples)
 Mud cracks
Sedimentary Structures

Structures formed during deposition
1-4, after deposition 5,6
1 2 3
4 5 6

Graded bedding, Jurassic of New
Jersey

Graded bedding
kasar
halus
kasar
halus

sorting
High energy enviroment Low energy enviroment

Cross stratification (berlaku semasa
transgression-regression air laut)

Important note
 Descriptive properties => interpretive
properties
 Geology => engineering
 Objective: to aid
planning, design, construction, mitigation, co
nservation, preservation

Sedimentary Environments
 Sedimentary environments are places where
sediments accumulate and sedimentary rocks
form. They can be grouped into:
 Terrestrial environments (non-marine)
– Rivers (fluvial environment)/sungai)
– Alluvial fans (kipas lanar)
– Lakes (lacustrine environment)/tasik
- Swamps/paya
- Deserts (aeolian environment)
- Glacial environments

 Transitional environments (at the
transition between the marine and non-
marine environments)
 Beach and barrier islands
 Delta
 Lagoons
 Estuaries

Marine environments
 Continental shelf
 Continental slope and rise (deep sea fans)
 Abyssal plain
 Reefs (karang)

Continental enviroment: fluvial

Model for landform development

Batuan mendak
 Batuan hos kepada petroleum dan gas asli
 Mendapan mineral spt Cu, Pb, Zn, Tungsten
 dll

 14
Si
28.0855(3)The essentials
 Name: silicon
 Symbol: Si
 Atomic number: 14
 Atomic weight: 28.0855 (3) r
 CAS Registry ID: 7440-21-3
 Group number: 14
 Group name: (none)
 Period number: 3
 Block: p-block
 Description
 Here is a brief description of silicon.
 Standard state: solid at 298 K
 Colour: dark grey with a bluish tinge
 Classification: Semi-metallic

www.webelements.com

Silicon is present in the sun and stars and is a
principal component of a class of meteorites known
as aerolites. Silicon makes up 25.7% of the earth's
crust by weight, and is the second most abundant
element, exceeded only by oxygen. It is found
largely as silicon oxides such as sand
(silica), quartz, rock
crystal, amethyst, agate, flint, jasper and opal.
Silicon is found also in minerals such as
asbestos, feldspar, clay and mica.
Silicon is important in plant and animal life.
Diatoms in both fresh and salt water extract silica
from the water to use as a component of their cell
walls. Silicon is an important ingredient in steel.
Silicon carbide is one of the most important
abrasives. Workers in environments where
silicaceous dust is breathed may develop a serious
lung disease known as silicosis.

 Hydrolysis and condensation of substituted
chlorosilanes can be used to produce a very
great number of polymeric products, or
silicones. These range from liquids to
hard, glasslike solids with many useful
properties.
 Elemental silicon transmits more than 95%
of all wavelengths of infrared and and has
been used in lasers to produce coherent
light at 456 nm.
Important facts

Isolation
 Here is a brief summary of the isolation of silicon.
 There is normally no need to make silicon in the
laboratory as it is readily available commercially. Silicon
is readily available through the treatment of
silica, SiO2, with pure graphite (as coke) in an electric
furnace.
 SiO2 + 2C Si + 2CO
 Under these conditions, silicon carbide, SiC, can form.
However, provided the amount of SiO2 is kept
high, silicon carbide may be eliminated.
 2SiC + SiO2 3Si + 2CO
 Very pure silicon can be made by the reaction of SiCl4
with hydrogen, followed by zone refining of the resultant
silicon.
 SiCl4 + 2H2 Si + 4HCl

Fakta penting mengenai Malaysia

Most cities and large towns in the
Peninsula are located on a thin
surface alluvium over limestone
and granite.

 Malaysia is generally formed by highland,
floodplain, and coastal zones (Figure 1.2 ).
In the Peninsula, the Banjaran Titiwangsa
from north to south divides the West Coast
and East Coast states, while in Sarawak the
Banjaran Kapuas Hula and Banjaran Iran
border Indonesia. All of these ranges are
governed by virgin forest

 Malaysia is warm and humid throughout the
year, as characterised by the equatorial
climate, and has an average annual rainfall
of more than 2500 mm with spatial variation
shown in Figure 1 . 3 .

 In the Peninsula wettest area is Taiping in Perak
whilst the driest is Kuala Pilah in Negeri Sembilan
(Figure 1 . 5 ).
 Average daily temperatures range from a
minimum of 25o C to a maximum of 33o C.
Relative humidity is high, sometimes exceeding
80%. Daytime cloudy hours are also high while
haze lately is a frequent occurrence that will
contribute to acid rains.

 Urbanisation poles are formed in many different
ways including;
 · centrally in dense arrangements such as
towns, cities, ports, commercial/business
centres, and new development areas
 · linearly along
road, highway, railway, river, estuary, and coastal
areas
 · randomly located, including villages and
high class residential areas

Next lecture
on metamorphic rocks

Luluhawa

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