Changes

==Definition of Depositional Environments==

==Definition of Depositional Environments==

Depositional environment is part of earth surface that has certain chemical, biology, and physics characteristics where sediments are laid on. There are 3 kinds of depositional environments, they are continental, marginal marine, and marine environments.<ref name=Bggs>Boggs, S., Jr,. 2009, Principles of Sedimentology and Stratigraphy Fourth Edition. New Jersey: Pearson Prentice Hall.</ref> Each environments have certain characteristic which make each of them different than others. And different depositional environment, will have different structure and texture of sediments.

Depositional environment is part of earth surface that has certain chemical, biology, and physics characteristics where sediments are laid on. There are 3 kinds of depositional environments, they are continental, marginal marine, and marine environments.<ref name=Bggs>Boggs, S., Jr,. 2009, Principles of Sedimentology and Stratigraphy Fourth Edition. New Jersey: Pearson Prentice Hall.</ref> Each environments have certain characteristic which make each of them different than others. And different depositional environment, will have different structure and texture of sediments.

==Fluvial Systems==

==Fluvial Systems==

Fluvial deposits, also known as [[alluvial]] deposits, involves sediments that are formed by activities of river, stream, and associated with gravity flow process. There are 2 kinds of environmental settings from fluvial deposits, which are alluvial fan and river.<ref name=Bggs />

Fluvial deposits, also known as [[alluvial]] deposits, involves sediments that are formed by activities of river, stream, and associated with [[gravity]] flow process. There are 2 kinds of environmental settings from fluvial deposits, which are alluvial fan and river.<ref name=Bggs />

==Alluvial Fan and Its Classification==

==Alluvial Fan and Its Classification==

[[Alluvial]] deposits has gross – cone-like shape and form a convex-up construction in [[cross section]]. These deposits are consist of abudant gravel-sand detritus on mostly fairly steep depositional slope. They are poorly sorted and are common from the base of mountain range with many sediment supplies. Based on depositional processes, there are 2 kinds of alluvial fans, debris-flow-dominated fans and stream-flow-dominated fans. As the flow of sediments from high relief area (mountain range) comes to a lower area, they are free to spread out with help of gravity. Debris-flow deposits are poorly sorted with the lack of sediment structure, except the reverse graded bedding in their basal parts. They contain various sizes of sediment, and mostly impermeable and nonporous because of the high amount of muddy matrix.

[[Alluvial]] deposits has gross – cone-like shape and form a convex-up construction in [[cross section]]. These deposits consist of abundant gravel-sand detritus on mostly fairly steep depositional slope. They are poorly sorted and are common from the base of mountain range with many sediment supplies. Based on depositional processes, there are 2 kinds of alluvial fans, debris-flow-dominated fans and stream-flow-dominated fans. As the flow of sediments from high relief area (mountain range) comes to a lower area, they are free to spread out with help of gravity. Debris-flow deposits are poorly sorted with the lack of sediment structure, except the reverse graded bedding in their basal parts. They contain various sizes of sediment, and mostly impermeable and nonporous because of the high amount of muddy matrix.

There is also mudflow which is similar to debris flow but mostly contains finer size of sediments than debris flow. Debris flow is also associated with landslide, the landslide is commonly as the source of sediments for debris flow. Stream-flow processes are the principal transport mechanism of stream-flow dominated fans. There are sheetflood and incised channel flow. Sheetflood is a broad expanse of unconfined , sediment-laden runoff water moving downslope , commonly proudced by catastrophic discharge. And incised-channel flow takes place through channel, 1-4 m high, incised into the upper fan.

There is also mudflow which is similar to debris flow but mostly contains finer size of sediments than debris flow. Debris flow is also associated with landslide, the landslide is commonly as the source of sediments for debris flow. Stream-flow processes are the principal transport mechanism of stream-flow dominated fans. There are sheetflood and incised channel flow. Sheetflood is a broad expanse of unconfined , sediment-laden runoff water moving downslope , commonly produced by catastrophic discharge. And incised-channel flow takes place through channel, 1-4 m high, incised into the upper fan.

==Characteristics of Alluvial Fan==

==Characteristics of Alluvial Fan==

[[Alluvial]] fans are cone-shape and have many distributary channels. From the fanhead to the fantoe and also from the cross section, it’s concave upward. Alluvial fan deposits are mostly gravel-sized sediments and show down-fan decreased in grain size and bed thickness and an increase in sediment sorting. The characteristics of debris-flow-dominated fan are the poorly sorted sediment with coarse grain sizes and muddy matrix. But the stream-flow- dominated fans are more sheetlike deposits of finer grain sizes and may have well sorted, laminated, cross-bedded or nearly strcutureless. Mostly, alluvial fan deposits have strongly developed thickening and coarsening-upward succesion, which are caused by active fan progradation or outbuilding. But there are some fan deposits have thinning and finning upward succession which are caused by fan retrogradation.

[[Alluvial]] fans are cone-shape and have many distributary channels. From the fanhead to the fantoe and also from the cross section, it’s concave upward. Alluvial fan deposits are mostly gravel-sized sediments and show down-fan decreased in [[grain size]] and bed thickness and an increase in sediment sorting. The characteristics of debris-flow-dominated fan are the poorly sorted sediment with coarse grain sizes and muddy matrix. But the stream-flow- dominated fans are more sheetlike deposits of finer grain sizes and may have well sorted, laminated, cross-bedded or nearly strcutureless. Mostly, alluvial fan deposits have strongly developed thickening and coarsening-upward succession, which are caused by active fan progradation or outbuilding. But there are some fan deposits have thinning and finning upward succession which are caused by fan retrogradation.

==River Systems==

==River Systems==

===Floodplain Deposition===

===Floodplain Deposition===

Floodplain are strips of land connected to the river and commonly formed in seasonal flood. Floodplains can be present in braided and also meandering rivers. When the stream flood, overtop its banks, deposition happens on natural leeves. This deposition will happen again and again until forming a land along the side of the bank, then formed floodplain. Natural-leeve deposits form on the concave or steep-bank side of meander loops which connected to the channel as a result of sudden lost of competence. Their characteristics are the structure of stratified fine sands overlain by laminated mud.

Floodplain are strips of land connected to the river and commonly formed in seasonal flood. Floodplains can be present in braided and also meandering rivers. When the stream flood, overtop its banks, deposition happens on natural levees. This deposition will happen again and again until forming a land along the side of the bank, then formed floodplain. Natural-levee deposits form on the concave or steep-bank side of meander loops which connected to the channel as a result of sudden lost of competence. Their characteristics are the structure of stratified fine sands overlain by laminated mud.

===Characteristics of Fluvial Deposits===

===Characteristics of Fluvial Deposits===

The common properties of fluvial deposits are, they consist of sand and gravel grain size and also mud in floodplain deposits of meandering systems, and they have moderate to poor sorting. The deposits of point bars and braid bars are generally fining upward grain size. The repeat of channel shifting and bar migration of braided rivers produces vertical stacking of bar deposits can be separated by mudstones. And the repeat of meander migration produces vertical stacking of fining upward succesion in meandering river deposits. Many sediment structures like planar and trough [[cross-bedding]], upper-flow-regime planar bedding, and ripple-marked surface occur in fluvial deposits. From fluvial deposits, the paleocurrent can be determined especially in meandering rivers. And fluvial deposits can also contain a variaty of fossil hard parts of terrestrial animals and also trace fossils which are created by both plants and animals.

The common properties of fluvial deposits are, they consist of sand and gravel grain size and also mud in floodplain deposits of meandering systems, and they have moderate to poor sorting. The deposits of point bars and braid bars are generally fining upward grain size. The repeat of channel shifting and bar migration of braided rivers produces vertical stacking of bar deposits can be separated by mudstones. And the repeat of meander migration produces vertical stacking of fining upward succession in meandering river deposits. Many sediment structures like planar and trough [[cross-bedding]], upper-flow-regime planar bedding, and ripple-marked surface occur in fluvial deposits. From fluvial deposits, the paleocurrent can be determined especially in meandering rivers. And fluvial deposits can also contain a variety of fossil hard parts of terrestrial animals and also trace fossils which are created by both plants and animals.

==Eolian Desert Systems==

==Eolian Desert Systems==

Desert areas cover about 20-25 percent of present land surface, within latitudinal belts about 10-30 degrees north and south of equator. These areas have dry climate with low air pressure and low rainfall. These dry areas are dominated by wind activity and covered by sand. There are 3 subenvironments of this desert system, they are aluvial fan, ephemeral river which is present when rain season, and ephemeral lake.<ref name=Bggs />

Desert areas cover about 20-25 percent of present land surface, within latitudinal belts about 10-30 degrees north and south of equator. These areas have dry climate with low air pressure and low rainfall. These dry areas are dominated by wind activity and covered by sand. There are 3 subenvironments of this desert system, they are alluvial fan, ephemeral river which is present when rain season, and ephemeral lake.<ref name=Bggs />

==Transport dan Depositional Processes in Desert Systems==

==Transport dan Depositional Processes in Desert Systems==

As explaned before, desert areas are dominated by wind activity. In these areas, wind plays roles as erosion and also transport agent. Wind is less effective erosion agent than water, but more effective in become transport agent of finer sand sediments. Wind transports sediment almost in the same way as water, with three ways : traction, saltation, and suspension. Effectively, wind transports sediment by suspension. But coarser sediment can also transported by traction or saltation by wind with unusual high velocity. This transport proccess will produce 3 kinds of deposits : dust (silt) deposits, sometimes referred to loess which contains finer sediments from far distance; sand deposits, which is well sorted; and lag deposits, which consist of gravel-size sediments that are too large to be transported by the wind, so it forms deflation pavement.

As explaned before, desert areas are dominated by wind activity. In these areas, wind plays roles as erosion and also transport agent. Wind is less effective erosion agent than water, but more effective in become transport agent of finer sand sediments. Wind transports sediment almost in the same way as water, with three ways : traction, saltation, and suspension. Effectively, wind transports sediment by suspension. But coarser sediment can also transported by traction or saltation by wind with unusual high velocity. This transport process will produce 3 kinds of deposits : dust (silt) deposits, sometimes referred to loess which contains finer sediments from far distance; sand deposits, which is well sorted; and lag deposits, which consist of gravel-size sediments that are too large to be transported by the wind, so it forms deflation pavement.

From this transport, there are many structures and bedforms that are formed. Such as ripples, sand dunes, and cross-bedds. Bedforms that develop during wind transport range from ripple with 0,01 m long and a height of few milimiters to dunes with 500-600 m long and 100 m of height. There’s also draas which is gigantic bedform that has up to 5,5 km long and height of 400 m (Wilson, 1972; McKee, 1982). Environments of deserts are divided into 3 main subenvironments : dunes, interdune, and sand sheet (Ahlbrandt and Fryberger, 1982).

From this transport, there are many structures and bedforms that are formed. Such as ripples, sand dunes, and cross-beds. Bedforms that develop during wind transport range from ripple with 0,01 m long and a height of few milimiters to dunes with 500-600 m long and 100 m of height. There’s also draas which is gigantic bedform that has up to 5,5 km long and height of 400 m (Wilson, 1972; McKee, 1982). Environments of deserts are divided into 3 main subenvironments : dunes, interdune, and sand sheet (Ahlbrandt and Fryberger, 1982).

==Dunes==

==Dunes==

Dunes are formed by wind deposition and transport, then the sediments accumulate in a variety of dune forms. Dune morphology is determined by the availability of sand, wind intensity, and the variability of wind directions (Lancaster, 1999; Pye and Tsoar, 1990). Dune consists of well sorted and well rounded grains, mostly quartz rich , but also heavy minerals and rock fragments are present. Coastal dune consists of many ooids , skeletal fragments, and other carbonate grains. Eolian dune is characterized by the presence of large [[cross bedding]].

Dunes are formed by wind deposition and transport, then the sediments accumulate in a variety of dune forms. Dune morphology is determined by the availability of sand, wind intensity, and the variability of wind directions (Lancaster, 1999; Pye and Tsoar, 1990). Dune consists of well sorted and well rounded grains, mostly [[quartz]] rich , but also heavy minerals and rock fragments are present. Coastal dune consists of many ooids , skeletal fragments, and other carbonate grains. Eolian dune is characterized by the presence of large [[cross bedding]].

==Interdune==

==Interdune==

Interdune areas occur between dunes and bounded by dunes or other eolian deposits such as sand sheets.<ref name=Bggs /> Interdunes may be formed by erosion or deposition. Erosional interdunes are present as disconformity overlain by thin, discontinuous, winnowed lag deposits. All interdunes deposits are characterized by low angle stratification (<~10°). Dry interdunes or interdunes that are wet occasionally are more common than wet interdunes. Dry interdunes have ripple-related wind- transport-processes, grainfall in the wind shadow in the lee of dunes, or sandflow from adjacent dunes. These deposits are coarse, bimodal, poorly sorted, and poorly laminated layers. Wet interdune deposits are finer than the dry interdunes deposits. They are usually in silt or clay size which are trapped by semipermanent bodies of water. This deposits contain freshwater organisms such as pelecypod, gastropod, diatom and ostracod. [[Evaporite]] interdunes occur where drying of shallow ephemeral lakes or evaporation of damp surface causes precipitation of carbonate minerals : gypsum or anhydrite. This sediments may be characterized by desiccation cracks, raindrop imprints, , evaporite layers, and pseudomorphs.

Interdune areas occur between dunes and bounded by dunes or other eolian deposits such as sand sheets.<ref name=Bggs /> Interdunes may be formed by erosion or deposition. Erosional interdunes are present as disconformity overlain by thin, discontinuous, winnowed lag deposits. All interdunes deposits are characterized by low angle stratification (<~10°). Dry interdunes or interdunes that are wet occasionally are more common than wet interdunes. Dry interdunes have ripple-related wind- transport-processes, grainfall in the wind shadow in the lee of dunes, or sandflow from adjacent dunes. These deposits are coarse, bimodal, poorly sorted, and poorly laminated layers. Wet interdune deposits are finer than the dry interdunes deposits. They are usually in silt or clay size which are trapped by semipermanent bodies of water. This deposits contain freshwater organisms such as pelecypod, gastropod, diatom and ostracod. [[Evaporite]] interdunes occur where drying of shallow ephemeral lakes or evaporation of damp surface causes precipitation of carbonate minerals: [[gypsum]] or [[anhydrite]]. This sediments may be characterized by desiccation cracks, raindrop imprints, , evaporite layers, and pseudomorphs.

==Sheet Sands==

==Sheet Sands==

==Lacustrine Systems==

==Lacustrine Systems==

1-2 percent of eart surface is covered by lake. Lake deposits are formed by complex chemical, physical, and biological processes. The physical processes are from rivers, waves, streams, and deposition. The chemical processes are from the chemical deposition, and the biology processes are from biological product and organic deposits. The basin of lake can be formed by many mechanisms, such as tectonic movements (rifting, faulting), glacial processes (ice scouring, ice damming, moraine damming), landslide or other mass movements, volcanic activity, deflation, and fluvial activity.

1-2 percent of the earth's surface is covered by lake. Lake deposits are formed by complex chemical, physical, and biological processes. The physical processes are from rivers, waves, streams, and deposition. The chemical processes are from the chemical deposition, and the biology processes are from biological product and organic deposits. The basin of lake can be formed by many mechanisms, such as tectonic movements (rifting, faulting), glacial processes (ice scouring, ice damming, moraine damming), landslide or other mass movements, volcanic activity, deflation, and fluvial activity.

Modern lakes are about a few tens of square meters to ten of thousands of square kilometers. There are 4 variables that determine the lake size and characters, they are basin- floor depth, sill height, water supply, and sediment supply.

Modern lakes are about a few tens of square meters to ten of thousands of square kilometers. There are 4 variables that determine the lake size and characters, they are basin- floor depth, sill height, water supply, and sediment supply.

===Chemical Processes===

===Chemical Processes===

In closed lakes, deposition of chemically processed sediments are common. There are many ions that are abundant in lake, but mostly carbonates are the most present. The evaporite deposits contain many evaporite minerals, such as gypsum, anhydrite, halite, and sylvite. The pH of lake is about 6 to 9, but it can become asidic in some volcanic lakes, and more alkaline in closed desert lakes.

In closed lakes, deposition of chemically processed sediments are common. There are many ions that are abundant in lake, but mostly carbonates are the most present. The evaporite deposits contain many evaporite minerals, such as gypsum, anhydrite, [[halite]], and sylvite. The pH of lake is about 6 to 9, but it can become acidic in some volcanic lakes, and more alkaline in closed desert lakes.

===Biological Processes===

===Biological Processes===

Many kinds of organisms live in lakes and when they die, their skeletals will be preserved in lake sediments. Siliceous diatoms are common in lake deposits. But there are also pelecypods, gastropods, calcareous algae, and ostracods that give contribution of carbonate materials in lake sediments.

Many kinds of organisms live in lakes and when they die, their skeletons will be preserved in lake sediments. Siliceous diatoms are common in lake deposits. But there are also pelecypods, gastropods, calcareous algae, and ostracods that give contribution of carbonate materials in lake sediments.

==Glacial Systems==

==Glacial Systems==

==Environmental Setting==

==Environmental Setting==

There are 4 zones : the basal (subglacial zone) which influenced by contact with the bed, the supraglacial zone which is the upper surface of the glacier, the ice-contact zone around the margin of glacier, and the englacial zone within the glacial interior.<ref name=Bggs /> Proglacial environment is influenced by melting ice but not with direct contact with ice, this environment includes glaciofluvial, glaciolacustrine, and glaciomarine settings. The periglacial environment is the wider areaand overlapping the proglacial environment. The basal zone is the area where erosion and plucking of underlying bed happens. The supraglacial zone and ice-contact zone are zones of melting where englacial debris carried by glacier accumulates as the glacier melts. The size of glacial environment ranges in various sizes. There are valley glaciers, piedmont glaciers, and ice sheets which have smallest to biggest size of glacial environments.

There are 4 zones : the basal (subglacial zone) which influenced by contact with the bed, the supraglacial zone which is the upper surface of the glacier, the ice-contact zone around the margin of glacier, and the englacial zone within the glacial interior.<ref name=Bggs /> Proglacial environment is influenced by melting ice but not with direct contact with ice, this environment includes glaciofluvial, glaciolacustrine, and glaciomarine settings. The periglacial environment is the wider area and overlapping the proglacial environment. The basal zone is the area where erosion and plucking of underlying bed happens. The supraglacial zone and ice-contact zone are zones of melting where englacial debris carried by glacier accumulates as the glacier melts. The size of glacial environment ranges in various sizes. There are valley glaciers, piedmont glaciers, and ice sheets which have smallest to biggest size of glacial environments.

==Marginal Marine==

==Marginal Marine==

==Deltaic System==

==Deltaic System==

Learning about Deltaic System is important because delta told as the host of petroleum, gasses, and coals. Herodotus, a greek philosopher, use the terms of Delta to describe a triangle shape of [[alluvial]] plain in the mouth of Nile River. Nowadays, although Delta doesn’t form a perfect triangle, the term Delta is still used to describe the subaerial or subaqueous deposition of fluvial processes in the body of water. Generally, delta is formed by the deposition and sedimentation of materials that are transported through the river in other body of water like sea. This process is called the constructive process. Beside the constructive process, delta is also influenced by the destructive processes like reworking and redistributing of sediment from marine system. The place in which the delta is formed has three requirements. First, it has to have a large and active drainage system. Second, the tectonic activity should be low. Last, it has to have a large supply of sediments.

Learning about Deltaic System is important because delta told as the host of petroleum, gasses, and coals. Herodotus, a Greek philosopher, use the terms of Delta to describe a triangle shape of [[alluvial]] plain in the mouth of Nile River. Nowadays, although Delta doesn’t form a perfect triangle, the term Delta is still used to describe the subaerial or subaqueous deposition of fluvial processes in the body of water. Generally, delta is formed by the deposition and sedimentation of materials that are transported through the river in other body of water like sea. This process is called the constructive process. Beside the constructive process, delta is also influenced by the destructive processes like reworking and redistributing of sediment from marine system. The place in which the delta is formed has three requirements. First, it has to have a large and active drainage system. Second, the tectonic activity should be low. Last, it has to have a large supply of sediments.

Based on the sedimentation processes, the morphology of delta can be classified as Delta Plain, Delta Front, and Prodelta.

Based on the sedimentation processes, the morphology of delta can be classified as Delta Plain, Delta Front, and Prodelta.

The Beach environment can be divided into several zones :

The Beach environment can be divided into several zones :

* The Backshore, which extends landward from the beach berm above high tide level and commonly includes back-beach dune deposits.

* The Backshore, which extends landward from the beach berm above high tide level and commonly includes back-beach dune deposits.

* The Foreshore, called littoral zone or zone between high tide leve to low tide level.

* The Foreshore, called littoral zone or zone between high tide level to low tide level.

* The Shoreface, called nearshore, located on low tide level to transition zone between beach and sediment on shelf.

* The Shoreface, called nearshore, located on low tide level to transition zone between beach and sediment on shelf.

===Barrier Island Systems===

===Barrier Island Systems===

The Barrier Island setting is composite of three separate environments. There are the sandy barrier-island chain itself (the subtidal to subaerial barrier-beach complex), the enclosed lagoon, estuary, or marsh behind it (the back-barrier, subtidal-intertidal region), and the channels that cut through the parrier and connect the back-barrier lagoon to the open sea (the subtidal-intertidal delta and inlet-channel complex).<ref name=Bggs /> Depositional processes and sediment transport are similar with the mainland beaches.

The Barrier Island setting is composite of three separate environments. There are the sandy barrier-island chain itself (the subtidal to subaerial barrier-beach complex), the enclosed lagoon, estuary, or marsh behind it (the back-barrier, subtidal-intertidal region), and the channels that cut through the barrier and connect the back-barrier lagoon to the open sea (the subtidal-intertidal delta and inlet-channel complex).<ref name=Bggs /> Depositional processes and sediment transport are similar with the mainland beaches.

[[File:Depositional_Environments_UGM_Fig-1.png|center|framed|Figure 1. Barrier Island Systems (Derived from Boggs<ref name=Bggs />)]]

[[File:Depositional_Environments_UGM_Fig-1.png|center|framed|Figure 1. Barrier Island Systems (Derived from Boggs<ref name=Bggs />)]]

==Estuarine==

==Estuarine==

Estuarine is the liquid part and has funnel shape. The estuarine associatwith the ocean. Based on dominant hydrologic characteristics and the kinds of sediment and sediment bodies, it divided into wave dominated, tide dominated, or mixed wave and tide dominated (Dalrymple, Zaitlin, and Boyd, 1992).

Estuarine is the liquid part and has funnel shape. The estuarine associated with the ocean. Based on dominant hydrologic characteristics and the kinds of sediment and sediment bodies, it divided into wave dominated, tide dominated, or mixed wave and tide dominated (Dalrymple, Zaitlin, and Boyd, 1992).

===Wave Dominated Estuary===

===Wave Dominated Estuary===

==Principal Kinds Of Deep-Sea Sediment==

==Principal Kinds Of Deep-Sea Sediment==

===Kind of deep-sea sediment : Hemipelagic Mud===

===Kind of deep-sea sediment : Hemipelagic Mud===

Hemipelagic mud deposited on very low current. It is mostly found in the basin slope in front of arc.Generally it has the color of grey to green or green to reddish brown. It has mud to shale size. Beside formed from the remains of living things, hemipelagic mud also formed of soft terrigenous quartz, fieldspar mika, mineral lempung, and vilcanin material. Hemipelagic mud can also be found in the back-arc basin, which is formed by the activities of planktonic organism.

Hemipelagic mud deposited on very low current. It is mostly found in the basin slope in front of arc.Generally it has the color of grey to green or green to reddish brown. It has mud to shale size. Beside formed from the remains of living things, hemipelagic mud also formed of soft terrigenous [[quartz]], fieldspar mika, mineral lempung, and vilcanin material. Hemipelagic mud can also be found in the back-arc basin, which is formed by the activities of planktonic organism.

===Kind of deep-sea sediment : Turbidite===

===Kind of deep-sea sediment : Turbidite===