Siliciclastic Rocks Francis. 2014 Eolian Dune Cross-Bedding.

Slides:



Advertisements
Similar presentations
Sedimentary and Metamorphic Rocks
Advertisements

Clastic/Detrital Sedimentary Rocks
Rocks Formed by Surface Processes
SEDIMENTS & SEDIMENTARY ROCKS
Chapter 3: The Classification of Clastic Sedimentary Rocks
Sedimentary Rocks II Sedimentary Rock II. Characteristics of clastic rocks Sedimentary Rock Types 5. Color: presence of key components (can be minor by.
Sedimentary rocks Modified from and
Sediments and Sedimentary Rocks. Significance for Climate and CCS Form at the surface, so directly influnced by Earth’s climate, provide the climate record.
UNIT – 2 Detrital Sedimentary Rocks. Clastic Sediments and Sedimentary Rocks Clastic sediments are loose materials, however when these sediments under.
Chapter 7 Sedimentary Rocks
Chapter 8 – FROM SEDIMENT INTO SEDIMENTARY ROCK
Chapter Six Sediments & Sedimentary Rocks. Sediment Sediment - loose, solid particles originating from: –Weathering and erosion of pre-existing rocks.
EARTH MATERIALS VI The Rock Cycle: Clastic Sedimentary Rocks Professor Peter Doyle
Sedimentologi Kamal Roslan Mohamed TERRIGENOUS CLASTIC SEDIMENTS: GRAVEL, SAND & MUD.
Clastic Sedimentary Rocks Derived from the Mechanical Breakup and Redeposition of Older Rocks.
Sediment and Sedimentary Rocks Physical Geology, Chapter 6
Sediments and Diagenesis The Rock Cycle is a group of changes. It is an ongoing process. Igneous rock can change into sedimentary rock or into metamorphic.
THE LANGUAGE OF THE EARTH – PART II SEDIMENTARY ROCKS.
Sedimentary Rocks. Sedimentary rocks form when sediment is compacted or cemented into solid rock Fig. 3-2, p.46.
Sedimentary Rocks and Depositional Environments
Sedimentary Rocks. What is a sedimentary rock? Sedimentary rocks are products of mechanical and chemical weathering They account for about 5 percent (by.
CHAPTER 6 SEDIMENTARY ROCKS.
Section 3: Sedimentary Rock
Sedimentary Rocks.
© 2011 Pearson Education, Inc. Earth: An Introduction to Physical Geology, 10e Tarbuck & Lutgens.
6.1/6.2 Guided Notes Hybrid. Weathering, Erosion and Deposition Produces Sediments: small pieces of rock that are moved and deposited by water, wind and.
Lecture Outlines Physical Geology, 13/e
Do Now: What are Sedimentary rocks?.  Explain the processes of compaction and cementation.  Describe how chemical and organic sedimentary rocks form.
The Importance of Sedimentary Rocks
1 Breccia Conglomerate Diamictite Sandstone Siltstone Shale New Clay Minerals Shale Clastic or Detrital Limestone Chert Diatomite Biochemical Evaporites.
SILICICLASTIC SEDIMENTARY ROCKS Prepared by Dr. F. Clark Department of Earth and Atmospheric Sciences, University of Alberta August 06.
Texture Detrital (Clastic Texture) vs. Chemical (Crystalline Texture)
Sedimentary Rocks Earth Science.
White Sands Nat’l Monument, NM
Sediments and Sedimentary Rocks What are sediments? Sediments are loose particles of former rocks. Sediments may be particles in the form of mineral grains.
Sedimentary Rocks Chapter 6. What Are Sediments? Loose particulate material In order of decreasing size.
Chapter 6 Sediments and Sedimentary Rocks
Chapter 6 Prepared by Iggy Isiorho for Dr. Isiorho Sediments and Sedimentary Rocks Index 
Section 3: Sedimentary Rock
Lecture Outlines Physical Geology, 14/e
SEDIMENTARY ROCKS A Brief Review.
Sedimentary Rocks.
Sedimentary Rocks Chapter 3 Section 3. Sedimentary  sedimentum Latin for ‘settling’ Rock formed from compressed or cemented layers (DEPOSITS) of sediment.
© 2011 Pearson Education, Inc. Sedimentary Rocks Earth, 10e - Chapter 7.
Sediment and Sedimentary Rocks Formation and Characteristics
CHAPTER 8: SEDIMENTARY ROCK
Lecture Outlines Physical Geology, 12/e
CHAPTER 6.3 SEDIMENTARY ROCKS.
Sedimentary Textures. Sediment Texture ► Grain size ► Sorting ► Grain rounding & grain shape ► Grain Fabric.
Sedimentary Rocks Sediments Lithification Deposition Transport Erosion
Sedimentary Rocks Igneous are the most abundant rock type, but are not the ones we see the most… Sedimentary rocks cover approximately 5% of the earths.
SEDIMENTARY ROCKS What are sediments? They are “loose” rock particles.
Lithification and Classes
Sedimentary Rock Formation. Formation Pre-existing rocks must be broken down Sediments: bits & pieces of pre-existing rock 2 general ways for this to.
Sedimentary Rocks Earth, 9e - Chapter 7. What is a sedimentary rock? Sedimentary rocks - products of mechanical and chemical weathering Comprise about.
Sediment and Sedimentary Rocks Geology
Lecture Outlines Physical Geology, 12/e
Sedimentary Rocks Sediments Lithification Deposition Transport Erosion
Sedimentary Rocks Forms when particles of rocks, plants, or animals are cemented together.
Sedimentary Rocks The products of deposition and lithification of weathered and eroded debris and chemical precipitants. BY FAR, most of the rocks exposed.
Sedimentary Rocks Deposited on or Near Surface of Earth by Mechanical or Chemical Processes.
Chapter 5.
Sedimentary Rocks A sedimentary rock is formed by the accumulation and compaction of sediments (rock pieces, minerals, animal parts, or chemical precipitates)
The Rock Cycle: Clastic Sedimentary Rocks
Formation of Sedimentary Rocks
Types of sedimentary Rocks
What events lead to the formation of
Sedimentary Rocks.
How they form, how they are classified, and why they are important.
Presentation transcript:

Siliciclastic Rocks Francis Eolian Dune Cross-Bedding

Siliciclastic rocks are the lithified accumulations of clastic grains of silicate minerals and rocks that have typically been deposited by water. The classification of siliciclastic rocks is based on grain size: Conglomerates > 30% gravel (>2 mm) and larger clastic Grains & Breccias: (< 5 %) Sandstones: > 50% sand-sized ( mm) clastic grains (~30%) Mudstones: > 50% silt ( mm) and (  65 %) / or clay (< mm)

Grain-Size versus Transport Mechanism There is a rough correspondence between the major grain size divisions and the transport mechanism, which is in return responsible for their physical separation during the fluid transport process, and the final distinction between sedimentary rocks. pebbles and larger are carried in the ‘bed load’ by traction - conglomerates sands are carried in ‘bed load’ by intermittent saltation and suspension - sandstones silts and clays are carried in suspension in the ‘wash load’ - shales

Conglomerates and Breccias (> 30% gravel (>2 mm) and larger clastic grains): Conglomerates and breccias can be distinguished by the sphericity of the clasts in the rock: if the clasts are rounded the rock is referred to as a conglomerate, if they are angular it is a breccia. With both conglomerates and breccias, grain-size, shape and orientation can be measured accurately in the field and may provide valuable information about the depositional environment. It is also important to note the ‘maximum clast size’, since it is often a reflection of the competency of the flow (i.e. a measure of the hydraulic energy of the transport process).

Polymictic Conglomerates

Monomictic Quartz-Pebble Conglomerate

Conglomerate Beds

Paraconglomerates - Diamictites

Paraconglomerates - Diamictites

Intraformational Breccias commonly monomictic

Magmatic Diatreme Breccia Wawa, Ontario typically matrix-supported & diamictic

anorthosite impact breccia Meteorite Impact Breccias Manicouagan Crater commonly matrix-supported & diamictic impactite

Sandstones ( > 50% sand-sized ( mm) clastic grains ): Sandstones are classified according to the types of clastic grains present (quartz, feldspar, & lithic fragments) and the presence (wackes) or absence (arenites) of significant fine-grained matrix material (< 0.03 mm). After this subdivision, they are described in terms of the types of preserved sedimentary structures, using terms like cross-bedded sandstone and relative maturity using criteria such as degree of sorting, roundness of the clasts, diversity of clast types, etc. greywacke

Arenites / Sandstones greywacke lithic arenite quartz arenite 15%

Arenites:fine-grained matrix not visible to naked eye (<10%). quartz arenite: quartz grains  90 %. (~ 35 %) Rare in modern environment, but quite common in late Precambrian and Paleozoic. Tend to be relatively mature, and may represent end-product of several cycles of erosion, transport, and deposition. Abundance of quartz arenites in Archean may reflect more intensive early Earth weathering conditions. Commonly silica cement predominates. synonym = orthoquartzite feldspathic arenite: visible feldspar / (felds + rock frag.)  50 %. (~ 15 %) C ommonly developed in granitic terranes and therefore restricted to local basins, but may also develop in cold or arid climates where feldspar is relatively resistant to decomposition, or in areas of high erosion rates. Typically cemented by calcite. synonym = arkose, if felds is K-spar lithic arenite:visible rock fragments / (felds + rock frag.)  50% (~ 20 %) The most abundant sandstone, as the sand-sized sediment loads of most modern rivers are dominated by lithic clasts. Furthermore, if greywackes are derived from the decomposition of lithic and feldspar clasts, then lithic arenites comprise  50 % of all arenites. Tend to be immature, poorly sorted. Typically cemented by calcite. synonym = sub-greywacke

Feldspathic Arenite Quartz Arenite Lithic Arenite

Greywacke: fine-grained ( 10-15%). (35%) The presence of the matrix gives the rock a dark grey colour. The clastic grains are polymictic and commonly relatively angular. The matrix is composed finely crystalline chlorite and sericite developed during diagenesis, along with silt-size quartz and albite. This fine-grained matrix has reacted with and obliterated the original outline of the clastic grains, acting as the cementing agent. There are two hypotheses for the origin of the matrix: 1. diagenetically altered interstitial silt and clay. 2. diagentically altered lithic and feldspar grains of a former lithic arenite. Most true greywackes are Paleozoic, or older in age, occurring as ‘flysch’ sequences of marine turbidites in response to orogenic events. Greywackes are not found in fluviatile or any other continental environment. Few modern sediments or sandstones, including marine turbidites, contain significant fine-grained matrix. The question is thus are all greywackes produced by diagenesis of lithic arenite protoliths, or was there something different about the transport and depositional mechanism of greywackes in the past which is not operative today. Relative abundance: lithic wacketypical feldspathic wackeless common quartz wacke rare

Mud Rocks: ( > 50% silt ( mm) and / or clay (< mm)) Mud rocks are composed of silt-sized quartz and feldspar grains and much smaller clay mineral particles. Depending of the relative proportions of these two types of grains, mud rocks range from siltstones to shales, mudstones, and claystones. Siltstones can be distinguish from shales and mudstones by biting a piece between your teeth. If it feels "gritty" then it is a siltstone, if it feels smooth or slick, then it is a shale or claystone. One of the most important features of mud rocks is their colour, an indication of their oxidation state and the paleo-environment of their deposition: Red shales are oxidized and typically represent sub-aerial detritus derived from the continents. They may represent in actual sub-aerial deposits, but also are formed by continental dust settling into organic-poor deep marine environments. Green shales are relatively reduced, and common in the shallow submarine environments depleted in oxygen by the decay of organic matter. Black shales are rich in organic matter and highly reduced, typically deposited in anoxic environments. They sometimes act as source rocks from which oil and gas are released during burial and diagenesis.