What causes particles to stick together when they take part in sedimentation?

[Mike Smith Cosmos]

I am just not quite sure what makes sedimentary red sand stick together? Or any other particles in the geological column. Is it pressure, time , heat , dehydration , or just the particles being held next to one another for so long a time period ( like 10's or 100's of millions of years) that the particles develop some form of atomic bonding , from a sheer , proximity perspective?

 

The end result is they ( the particles en mass ) become a rock in the process !

 

How ? By what mechanism are they held together ?

 

Mike

Edited November 23, 2015 by Mike Smith Cosmos

[StringJunky]

PDF direct download link; http://www.devon.gov.uk/geo-permianbrecciassandstonesandvolcanics.pdf

[Acme]

Sandstone

 

 

 

Cement

 

Cement is what binds the siliclastic framework grains together. Cement is a secondary mineral that forms after deposition and during burial of the sandstone.[4] These cementing materials may be either silicate minerals or non-silicate minerals, such as calcite.[4]

 

●Silica cement can consist of either quartz or opal minerals. Quartz is the most common silicate mineral that acts as cement. In sandstone where there is silica cement present the quartz grains are attached to cement, this creates a rim around the quartz grain called overgrowth. The overgrowth retains the same crystallographic continuity of quartz framework grain that is being cemented. Opal cement is found in sandstones that are rich in volcanogenic materials, and very rarely is in other sandstones.[4]

 

●Calcite cement is the most common carbonate cement. Calcite cement is an assortment of smaller calcite crystals. The cement adheres itself to the framework grains, this adhesion is what causes the framework grains to be adhered together.[4]

 

●Other minerals that act as cements include: hematite, limonite, feldspars, anhydrite, gypsum, barite, clay minerals, and zeolite minerals.[4]

[studiot]

Sandstones are loosly bound such that when you break a piece the fracture runs through the cement, not the grians of quartz.

 

Metamorphosed sandstone forms quartzite, where the grains fuse together to form large masses of quartz.

Breakage of quartzite shears through the quartz particles themselves.

 

UK examples are the Shropshire hills.

 

http://www.alamy.com/stock-photo-devils-chair-a-quartzite-tor-on-stiperstones-shropshire-england-uk-25989467.html

Edited November 23, 2015 by studiot

[Mike Smith Cosmos]

Ok. I am just not quite sure what makes sedimentary red sand stick together? Is it pressure, time , heat , dehydration , or just the sand particles being held next to one another for so long a time period ( like 10's of millions of years) that the particles develop some form of atomic bonding , from a sheer , proximity perspective?

 

Mike

Sandstones are loosly bound such that when you break a piece the fracture runs through the cement, not the grians of quartz. Metamorphosed sandstone forms quartzite, where the grains fuse together to form large masses of quartz.Breakage of quartzite shears through the quartz particles themselves. UK examples are the Shropshire hills. http://www.alamy.com/stock-photo-devils-chair-a-quartzite-tor-on-stiperstones-shropshire-england-uk-25989467.html

Now I understand , the cementation, of the Devonian Sand into Devonian sandstone .Interesting that you can see the supercontinent ( not Pangea ) feeding the U.k with the vast river drainage . By looking at the Red dot ( this is where .U.K. Is at the time ( below the equator at that Devonian time )

 

 

Mike

Edited November 24, 2015 by Mike Smith Cosmos

[Mike Smith Cosmos]

PDF direct download link; http://www.devon.gov.uk/geo-permianbrecciassandstonesandvolcanics.pdf

.

.

' There is Gold in them there Hills ' where I was yesterday ! Eek ! According to your citation ?

 

"

A long tongue of red rocks, including some volcanics, extends westward in the Crediton area, showing as an orange strip on the geological map. This is the result of deposition in a valley created by faulting the Crediton Trough - which gradually filled in with red breccias and sandstones. A flurry of excitement seized the area a few years ago when small amounts of gold were discovered in the volcanics and associated sediments, but no gold mining has yet been attempted."

 

I wondered why the National Trust representative looked at me a bit suspiciously , when I mentioned that " I wish to wander into the woods and investigate some ' Rocks'

 

 

Mike

Edited November 25, 2015 by Mike Smith Cosmos

[studiot]

You

I am just not quite sure what makes sedimentary red sand stick together?

 

So here are some points to consider.

 

There are two groups of red sandstones in Devon.

 

The Old Red Sandstone dating from the Devonian period 400 - 350 MYBP

 

and

 

The New Red Sandstone dating from the Permian / triassic 280 - 200 MYBP

 

They are quite different in character and origin.

 

Sediments range in size from pebbles through grains to fine particles.

They get this way through mechanical abrasion and also through grading during transport.

The pebbles and grains are usually harder minerals like quarz and feldspar,

The fine materials comprise clay minerals, other softer minerals like mica, calcareous material and even organic material.

Material of aqueous origin usually has a large mix, wind tends to make all the grains the same size and blow away the dust.

 

The deposited rocks become conglomerates, sandstones, mudstones or siltstones according to the particle sizes.

So sandstones are in the middle.

 

So when the mix is being deposited if there is a large percentage of fine material a Matrix is formed with grains and or pebbles included in it.

The matrix cements itself together by chemical action (the clay minerals are quite active) and this matrix holds the larger particles, grains and pebbles.

Mudstones, siltstones, chalk, limestones and so on are formed in this way.

 

If there is only a small percentage of fine material a Matrix does not form and the grains are first deposited loose.

Over time solutions containing cementing minerals work their way between the grains forming the looser sandstones.

These minerals are calcite, heamatite (the red in red sandstone), feldspar and some quartzite.

[Mike Smith Cosmos]

So here are some points to consider.

 

There are two groups of red sandstones in Devon.

 

The Old Red Sandstone dating from the Devonian period 400 - 350 MYBP

 

and

 

The New Red Sandstone dating from the Permian / triassic 280 - 200 MYBP

 

They are quite different in character and origin.

 

Sediments range in size from pebbles through grains to fine particles.

They get this way through mechanical abrasion and also through grading during transport.

The pebbles and grains are usually harder minerals like quarz and feldspar,

The fine materials comprise clay minerals, other softer minerals like mica, calcareous material and even organic material.

Material of aqueous origin usually has a large mix, wind tends to make all the grains the same size and blow away the dust.

 

The deposited rocks become conglomerates, sandstones, mudstones or siltstones according to the particle sizes.

So sandstones are in the middle.

 

So when the mix is being deposited if there is a large percentage of fine material a Matrix is formed with grains and or pebbles included in it.

The matrix cements itself together by chemical action (the clay minerals are quite active) and this matrix holds the larger particles, grains and pebbles.

Mudstones, siltstones, chalk, limestones and so on are formed in this way.

 

If there is only a small percentage of fine material a Matrix does not form and the grains are first deposited loose.

Over time solutions containing cementing minerals work their way between the grains forming the looser sandstones.

These minerals are calcite, heamatite (the red in red sandstone), feldspar and some quartzite.

.

Well today I delivered my Presentation / Discussion , in the form of going through my threads from the science forum on an overhead projector . Exactly as seen on my computer. (A) " the elements and molecules in the cloud......" (B) " the burning pea soup" and © How do sand granules stick together to become sandstone "

 

As regards cementation, I read your answer out ' word for word ' and showed some quotes from ' String Junkie and ' Acme ' . The group were suitably impressed with this open approach , more of a discussion . I acknowledged both the Science Forum as being the source of the information , and your local presence and comments from nearby , up country . And Ophiolite's expert comments throughout the threads as a renowned expert . Thanks for all your contributions ! Oops not forgetting Swansont and others ,

 

Thanks

 

MIKE

Edited November 26, 2015 by Mike Smith Cosmos

[Mike Smith Cosmos]

Unrecognised by me , not 5 minutes down the road toward Exeter , I have been practically driving over one of these lava flows , laid down over Red sandstone.

 

I pop in now and again for a cup of coffee at Killerton National trust garden and house site.

Good job it is 300 million years later ( if you click on the pictures to open them the writing becomes clear!)

 

This hill can be seen from the M5 motorway on the right , just before reaching Exeter. Unbeknown to me that it was an eruption of lava over red sandstone . This Map shows the aggromalate , and flow area .

 

This description identifies the three main aspects .

A) Point of entry of Lava. Agglomerate .

B) Basalt lava slick

C) Minnet

D) Red sandstone

 

Both the basalt rock and the Minnet were quarried to build the house and other buildings .

 

 

Mike

Edited November 30, 2015 by Mike Smith Cosmos

[studiot]

Minette doesn't only appear in the sout west UK, it also appears in the south west US.

 

https://books.google.co.uk/books?id=d_mqypQ0YgAC&pg=PA236&lpg=PA236&dq=minette+rock&source=bl&ots=XjhTkm4DCE&sig=8XzgvEGWh9FSPaICK1P73YphnHQ&hl=en&sa=X&ved=0ahUKEwiI-7aX8rfJAhXMOhQKHZm8BYsQ6AEIQTAK#v=onepage&q=minette%20rock&f=false