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Author Topic:   "The Flood" deposits as a sea transgressive/regressive sequence ("Walther's Law")
RAZD
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From: the other end of the sidewalk
Joined: 03-14-2004
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Message 211 of 224 (821510)
10-08-2017 5:21 PM
Reply to: Message 206 by Percy
10-08-2017 2:44 PM


Re: Walther's Law and Delta Formations
... and that they occur further out from the coast than beach sand because they're smaller, lighter particles and will only fall out of suspension in quieter waters (i.e., no waves crashing through a surf onto a beach).

After a point the only thing falling to the ocean floor is organic debris (diatom/foraminifera tests for example), airborne dust (from Africa/Sahara for example), and Cosmic Dust:

quote:
Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, as well as all over planet Earth.[1][2] Most cosmic dust particles are between a few molecules to 0.1 µm in size. A smaller fraction of all dust in space consists of larger refractory minerals that condensed as matter left the stars. It is called "stardust" and is included in a separate section below. The dust density falling to Earth is approximately 10−6/m3 with each grain having a mass between 10−16kg (0.1 pg) and 10−4 kg (100 mg).[3][4]

Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust (such as in the zodiacal cloud) and circumplanetary dust (such as in a planetary ring). In the Solar System, interplanetary dust causes the zodiacal light. Sources of Solar System dust include comet dust, asteroidal dust, dust from the Kuiper belt, and interstellar dust passing through the Solar System. The terminology has no specific application for describing materials found on the planet Earth except for dust that has demonstrably fallen to Earth. By one estimate, as much as 40,000 tons of cosmic dust reaches the Earth's surface every year.[3] In October 2011, scientists reported that cosmic dust contains complex organic matter (amorphous organic solids with a mixed aromatic–aliphatic structure) that could be created naturally, and rapidly, by stars.[5][6][7]

In August 2014, scientists announced the collection of possible interstellar dust particles from the Stardust spacecraft since returning to Earth in 2006.[8][9][10][11] In March 2017, scientists reported that extraterrestrial dust particles have been identified all over planet Earth.[2] According to one of the researchers, “Once I knew what to look for, I found them everywhere.”[1]


If these particles can be identified in sedimentary layers, then it becomes increasingly difficult for any creationist to argue that the layers were all laid down in ~400 days by the magical mystery tour globe trotting flying magical carpet flood.

Enjoy


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆Zen☯Deist
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This message is a reply to:
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edge
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Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


Message 212 of 224 (821526)
10-08-2017 9:09 PM
Reply to: Message 209 by Percy
10-08-2017 4:59 PM


What is the source of your chart? The chart's title is "Mineral assemblages of common igneous rocks and their relation to the interior structure of the Earth", but it includes many non-igneous rocks, like limestone and sandstone and shale and slate. Also, I can't make sense of the chart's organization - is it actually three separate charts? And why are there notes at the bottom about the moon?

Heh, heh ...

If someone wanted to confuse the layman about the structure of the earth, this is an excellent diagram to use. The important boundaries here are in the blue color. The main horizontal one would represent the boundary between crust and 'supracrustal' rocks (the ones we are familiar with as being deposited on the earth now.

Moving horizontally into different columns, you see different compositions and characteristics such as mineralogy, metamorphism and even some physical properties such as density, mass, etc.; representative of each layer within the earth.

As to comments about the moon and other oddities in the chart, someone is just showing off.

Same thing with the lack of concern for significant figures and geophysical jargon.

Way too complicated and some important things are left out. It's a chart that tries to explain everything and ultimately explains nothing.

Just my opinion.


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edge
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Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


(1)
Message 213 of 224 (821527)
10-08-2017 9:29 PM
Reply to: Message 206 by Percy
10-08-2017 2:44 PM


Re: Walther's Law and Delta Formations
About the siliciclastic muds, what you uncovered so far is already far more detailed than anything I know. I just assumed that they formed from the runoff from land, and that they occur further out from the coast than beach sand because they're smaller, lighter particles and will only fall out of suspension in quieter waters (i.e., no waves crashing through a surf onto a beach).

Yes, it takes higher velocities to keep larger grains either in suspension or moving in traction as a bed load.

The term siliciclastic is a compound term meaning it is of silicate composition (including clay minerals, quartz grains, feldspar grains, mica grains ... anything with silica in it) broken down from a previously existing rock.

Most sandstone beaches are eroded from siliceous rocks carried to the sea and abraded by rivers and wind, and sometimes eroded directly by wave action. Some beaches are carbonate (limestone) and others are 'black sand' (magnetite) and even green (dunite) all depending on the source rock. Quartz is the most common.


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RAZD
Member
Posts: 19309
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 2.2


Message 214 of 224 (821584)
10-09-2017 4:26 PM
Reply to: Message 213 by edge
10-08-2017 9:29 PM


Re: Walther's Law and Delta Formations
The term siliciclastic is a compound term meaning it is of silicate composition (including clay minerals, quartz grains, feldspar grains, mica grains ... anything with silica in it) broken down from a previously existing rock.

Most sandstone beaches are eroded from siliceous rocks carried to the sea and abraded by rivers and wind, and sometimes eroded directly by wave action. ...

So would I be correct in assuming that the division between "sands" and "siliciclastic muds" is more due to the definitions of "sand" and "silt" than any major difference in other characteristics?

I was also looking into the coccolith/foram ooze (and where I got into the cosmic dust component in Message 211):

quote:
Pelagic sediment

Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays.[1][2]

The composition of pelagic sediments is controlled by three main factors. The first factor is the distance from major landmasses, which affects their dilution by terrigenous, or land-derived, sediment. The second factor is water depth, which affects the preservation of both siliceous and calcareous biogenic particles as they settle to the ocean bottom. The final factor is ocean fertility, which controls the amount of biogenic particles produced in surface waters.[1][2]

In case of marine sediments, ooze does not refer to a sediment's consistency, but to its composition, which directly reflects its origin. Ooze is pelagic sediment that consists of at least 30% of microscopic remains of either calcareous or siliceous planktonic debris organisms. The remainder typically consists almost entirely of clay minerals. As a result, the grain size of oozes is often bimodal with a well-defined biogenic silt- to sand-size fraction and siliciclastic clay-size fraction. Oozes can be defined by and classified according to the predominate organism that compose them. For example, there are diatom, coccolith, foraminifera, globigerina, pteropod, and radiolarian oozes. Oozes are also classified and named according to their mineralogy, i.e. calcareous or siliceous oozes. Whatever their composition, all oozes accumulate extremely slowly, at no more than a few centimeters per millennium.[2][3]

Calcareous ooze is ooze that is composed of at least 30% of the calcareous microscopic shells—also known as tests—of foraminifera, coccolithophores, and pteropods. This is the most common pelagic sediment by area, covering 48% of the world ocean's floor. This type of ooze accumulates on the ocean floor at depths above the carbonate compensation depth. It accumulates more rapidly than any other pelagic sediment type, with a rate that varies from 0.3–5 cm/1000 yr.[1][2]

Siliceous ooze is ooze that is composed of at least 30% of the siliceous microscopic "shells" of plankton, such as diatoms and radiolaria. Siliceous oozes often contain lesser proportions of either sponge spicules, silicoflagellates or both. This type of ooze accumulates on the ocean floor at depths below the carbonate compensation depth. ...


Would I be correct in aligning "Carbonate sediments" with Calcereous ooze and "coccolith/foram ooze" with Siliceous ooze? So the boundary between them is defined by the carbonate compensation depth (which Dr A described in his awesome Introduction To Geology thread)?

This would mean that the boundary between sands and siliciclastic muds is mostly a matter of particle size definition, but the boundary between them and the pelagic oozes is based on biological/organic traces (of 30% or more) in the later, with the pelagic oozes further subdivided into carbonate and non-carbonate deposits, yes?

Thanks

Edited by RAZD, : .

Edited by RAZD, : .


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆Zen☯Deist
... to learn ... to think ... to live ... to laugh ...
to share.


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This message is a reply to:
 Message 213 by edge, posted 10-08-2017 9:29 PM edge has responded

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 Message 216 by edge, posted 10-09-2017 9:34 PM RAZD has acknowledged this reply

  
RAZD
Member
Posts: 19309
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 2.2


Message 215 of 224 (821593)
10-09-2017 5:29 PM
Reply to: Message 213 by edge
10-08-2017 9:29 PM


What I expect from Walther's Law for Delta Formations
So applying Walther's Law to delta formations,

This would mean that the boundary between sands and siliciclastic muds is mostly a matter of particle size definition, but the boundary between them and the pelagic oozes is based on biological/organic traces (of 30% or more) in the later, with the pelagic oozes further subdivided into carbonate and non-carbonate deposits, yes?

I would expect the sediment load from rivers to deltas to consist of mostly sands and siliciclastic mud, graded by distance from the river mouth to the widening plane of the delta as the river velocity dropped.

I would not expect pelagic oozes in the delta formations.

These deposit would progressively cover earlier delta formation deposits, and at their furthest deposition distance they would overlay the previous existing ocean floor -- coastal sediments along the coast and the pelagic oozes as the delta encroaches on the ocean/seas.

And I recollect a discussion (of Grand Canyon deposits?) of deltas forming these layers at the angle of (underwater) repose for the materials. This is cross-bedding, yes?

Enjoy


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆Zen☯Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
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 Message 217 by edge, posted 10-09-2017 10:01 PM RAZD has responded

  
edge
Member
Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


(1)
Message 216 of 224 (821616)
10-09-2017 9:34 PM
Reply to: Message 214 by RAZD
10-09-2017 4:26 PM


Re: Walther's Law and Delta Formations
So would I be correct in assuming that the division between "sands" and "siliciclastic muds" is more due to the definitions of "sand" and "silt" than any major difference in other characteristics?

Yes, however, you will find that the finer fractions will tend toward more phylosilicate minerals such as clays. And that is fine. The final products of weathering are quartz and various species of clay.

Would I be correct in aligning "Carbonate sediments" with Calcereous ooze and "coccolith/foram ooze" with Siliceous ooze?

Essentially, yes. A real sedimentologist could probably tell you all of the exceptions and ramificatins, but that would be my understanding.

So the boundary between them is defined by the carbonate compensation depth (which Dr A described in his awesome Introduction To Geology thread)?

That is a major global factor.

This would mean that the boundary between sands and siliciclastic muds is mostly a matter of particle size definition, but the boundary between them and the pelagic oozes is based on biological/organic traces (of 30% or more) in the later, with the pelagic oozes further subdivided into carbonate and non-carbonate deposits, yes?[/qs]
That would be accurate.


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edge
Member
Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


(1)
Message 217 of 224 (821637)
10-09-2017 10:01 PM
Reply to: Message 215 by RAZD
10-09-2017 5:29 PM


Re: What I expect from Walther's Law for Delta Formations
I would expect the sediment load from rivers to deltas to consist of mostly sands and siliciclastic mud, graded by distance from the river mouth to the widening plane of the delta as the river velocity dropped.

Here is a river delta, the Ebro, which show how the river transports sand to the delta where it is deposited and then redistributed into spits and bars by longshore current.

The ocean is just reworking the deltaic sediments at the interface.

I would not expect pelagic oozes in the delta formations.

Correct, deltaic deposits are simply an extension of fluvial deposition.

Rivers are temporary. Oceans are not.

Perhaps more tomorrow...


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RAZD
Member
Posts: 19309
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 2.2


Message 218 of 224 (821651)
10-09-2017 10:28 PM
Reply to: Message 217 by edge
10-09-2017 10:01 PM


Re: What I expect from Walther's Law for Delta Formations
why does that picture make me think of a penguin


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆Zen☯Deist
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edge
Member
Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


(1)
Message 219 of 224 (821811)
10-13-2017 12:12 AM
Reply to: Message 218 by RAZD
10-09-2017 10:28 PM


Re: What I expect from Walther's Law for Delta Formations
why does that picture make me think of a penguin

I thought it was a ghost ...

Which may be appropriate since the delta will be lost in the geological record as a lobe of channels and sands and overbank deposits at the base of a transgressive beach sand.


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Pressie
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Posts: 1858
From: Pretoria, SA
Joined: 06-18-2010
Member Rating: 2.1


(1)
Message 220 of 224 (821822)
10-13-2017 6:51 AM
Reply to: Message 219 by edge
10-13-2017 12:12 AM


Re: What I expect from Walther's Law for Delta Formations
That's basically what we get under, in and around mineable Coal Seams 2 and 4 in the Witbank Coalfield. Both these seams have lobes of channels and overbank deposits at the base of transgressive beach sands. And they split into different seams and come together again, depending on where the deltas were and what happened in the "swamps".
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edge
Member
Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


Message 221 of 224 (821878)
10-13-2017 10:08 PM
Reply to: Message 220 by Pressie
10-13-2017 6:51 AM


Re: What I expect from Walther's Law for Delta Formations
Good points. Unfortunately, it has to be kind of basic. Deltaic deposits could consume a career in geology. The thing that makes it easier is the presence of those transgressive sands. I am familiar with the 20 Mile Sandstone in the Willaims Fork Formation of Colorado. A great marker bed and easy geology. Some nice fossils too.
They tend to preserve nice seams below them. There are some regressive sands above, usually disncontinuous and much thinner.

So, for the layman, think of the delta deposits as a kind of swamp, partly marine partly terrestrial. The coal seams would represent a swampy area of high organic content ... and a river runs through it ... The beach is always there on a delta because waves wash the silt away and that sand moves along the shore with currents to form beaches far away. As the sea level rises, the beach moves inland until the high stand is reached and the sea recedes again. This happened numerous times in North America during the late Paleozoic and again in the late Cretaceous. Not sure what/ when happened in South Africa.


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Pressie
Member
Posts: 1858
From: Pretoria, SA
Joined: 06-18-2010
Member Rating: 2.1


Message 222 of 224 (821990)
10-17-2017 7:14 AM
Reply to: Message 221 by edge
10-13-2017 10:08 PM


Re: What I expect from Walther's Law for Delta Formations
In my country, very similar, except that it happend in a fresh water environment with a big freshwater lake in the middle and that the coal deposits were formed during the Late Carboniferous (few lenses) , the Permian (most of the coal) and Early Triassic (big, "coaly" deposits such as the Waterberg coal).

In SA we don't find Cretaceous coal at all.

Edited by Pressie, : No reason given.

Edited by Pressie, : No reason given.

Edited by Pressie, : No reason given.


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edge
Member
Posts: 4002
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 2.8


Message 223 of 224 (822083)
10-18-2017 9:42 PM
Reply to: Message 222 by Pressie
10-17-2017 7:14 AM


Re: What I expect from Walther's Law for Delta Formations
In my country, very similar, except that it happend in a fresh water environment with a big freshwater lake in the middle and that the coal deposits were formed during the Late Carboniferous (few lenses) , the Permian (most of the coal) and Early Triassic (big, "coaly" deposits such as the Waterberg coal).

I think that in most places the waters are fresh to brackish. These are mostly swamps and if no one is intercepting the surface and groundwater flow they should be more or less fresh. The Everglades in Florida would be an example where the flows are of fresh water to the south. In that case, however, we are getting salt water incursion into the water table.

This goes back to the delta question where we have fresh water flowing into the ocean to some degree. The Amazon supposedly forms brackish zones far into the Atlantic Ocean, particularly at the surface. I haven't tried to drink it...

I think someone mentioned the Amazon delta. The curious thing is that it is so small...


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RAZD
Member
Posts: 19309
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 2.2


Message 224 of 224 (822097)
10-19-2017 8:50 AM
Reply to: Message 223 by edge
10-18-2017 9:42 PM


Re: What I expect from Walther's Law for Delta Formations
I think someone mentioned the Amazon delta. The curious thing is that it is so small...

Isn't the Amazon very wide and flat for miles inland? Wouldn't that be the same deposition environment as a delta so only the finest smallest lightest material makes it to the mouth?

Also I think there is a north flowing coastal current that could easily carry the material material away from the mouth.

Just wondering

Enjoy


we are limited in our ability to understand
by our ability to understand
RebelAmerican☆Zen☯Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

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