Ask a Geologist

[Orogeny]

This is a stupid game. If you know the answer, then you already know the question. What else do you need?

I have been more than accommodating with you, Jazer. I answered your questions as I thought they were presented and when that wasn't quite right, I tried to understand what you wanted. Yet all I've gotten is resistance. If you're unable to participate in a way that jibes with the intent of the thread, do the Christian thing and vacate it.

 

[metherion]

Ah ha, an actual GEOLOGY question! (Well, maybe mineralogy question...)

What is the melting point/decomposition temperature of niggliite? Niggliite has come up in the inorganic chemistry term paper I'm doing, and while I don't need those values for the paper, I'm curious just because I can't find it.

Metherion

 

[Orogeny]

I found it on Anglesey, North Wales but it came from a pile of spoil so it could have come from anywhere in the North Wales area.

Sorry no picture available, I found this thing years ago and had it on my bookshelf for ages. Sadly when I went to Uni my mother threw it away because she "thought it was ugly". Real shame as it was pretty cool looking and it looked like it has a partial fossil of a fish or something in there too.

After a bit of research, it appears that indeed much of Wales was a carbonate platform during the early Carboniferous, about 330 million years ago (http://www.app.pan.pl/archive/published/app25/app25-577.pdf). At this time, the dominant coral was the Rugosans (also known as the horn coral), a now extinct () order.

[blog]

As a child (I must have been 10 or so), I found a Rugosan while walking in a pasture with my grandfather in Oklahoma. I was so excited because I was convinced it was a dinosaur tooth. I took it home, and it became the first piece of a small rock collection. I forgot about the collection for years, and happened across it as Iwas cleaning out a closet several years ago. As I was sifting through the box, I came upon the 'tooth', and was, I think, even more excited upon realization that it was a Rugosan than I had been as a youngster. I was well on in my undergrad geology studies, but the moment a coral excited me more than a dinosaur was when I knew without doubt I was on the right path, and in it for the right reasons.

[/blog]

 

[Jazer]

do the Christian thing and vacate it.

I will have to because it would be a violation of forum rules to tell you how dysfunctional you appear to be.

 

[Assyrian]

Cement! Refer back to post 23: The sand grains (referred to by nerds [me] as 'framework grains') are the dark, roundish things that dominate the frame. The brighter areas in between are cement. This particular example is cemented by calcite, and all of the pore space that was in the sediment when it was deposited has been filled by the cement. However, many, many different minerals can be cements. Quartz, carbonate (calcite, dolomite, etc.), salts (halite, gypsum, anhydrite, etc.), and clays are quite common cements, but cement can take almost any form. Referring back to our picture, we can actually see a couple of different cementation 'events'. The first was most likely an 'early marine' cementation event, common in carbonates. This cementation happens almost as soon as the sediment is deposited, and is represented here by a thin layer of very small, prismatic crystals [bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse] the edges of the grains themselves. Squint! They're there! They look a bit like this:

The second event is represented by larger, somewhat rounded-looking crystals that fill the remainder of the pore. This event must have happened while the rock was buried deep underground, since the cement fills a fracture that runs ENE across the lower right corner of the picture. Fractures of this type are typically from compaction, which is a result of a heavy (thick) sedimentary overburden.

Sedimentary cements are a chemical precipitate, formed as mineral-rich ground water flows through the pores in the rock.

In the case of rocks made of small, clay sized grains (mudstones and shales, as well as wackestones, which are muddy with dispersed sand-sized grains), cementation takes a back seat to compaction. Muddy rocks can be compacted by up to a factor of ten, and typically have too little pore space for the transmission of ion-bearing waters.

Are these (a) irreversible reactions that produce insoluble cement?
(b) soluble salts but they fill up the gaps and exclude water that would dissolve them again?
Or (c) part of how rocks are eroded by rain.

 

[juvenissun]

Are these (a) irreversible reactions that produce insoluble cement?
(b) soluble salts but they fill up the gaps and exclude water that would dissolve them again?
Or (c) part of how rocks are eroded by rain.

You reminded me (geo)scientists in 18th Century. Good for you.

While people may answer your question in detail, a reminder from me is: the physical/chemical conditions on the surface is very different from that in the ground.

 

[Orogeny]

Ah ha, an actual GEOLOGY question! (Well, maybe mineralogy question...)

What is the melting point/decomposition temperature of niggliite? Niggliite has come up in the inorganic chemistry term paper I'm doing, and while I don't need those values for the paper, I'm curious just because I can't find it.

Metherion

I'll tell you what, I spent a while searching the web and a couple mineralogical databases before resorting to the trusty old hard copy mineralogy texts. I went to five different mineralogy and ore mineralogy books, and only one even mentioned niggliite, and then it was simple optical characteristics.

So in other words, I can be of no help to you. Sorry

 

[Orogeny]

I will have to because it would be a violation of forum rules to tell you how dysfunctional you appear to be.

You're projecting again, Jazer.

 

[Orogeny]

Are these (a) irreversible reactions that produce insoluble cement?

Oh no, the cements are absolutely soluble. Cementation histories can be incredibly complex, and if the effort is made to understand that history, a lot can be said about the burial history of the rock, which can help us understand basin tectonics, groundwater chemistry and transport history, interplay with surrounding lithologies, and even tell us whether there was, at one point, oil or gas in the rock.

(b) soluble salts but they fill up the gaps and exclude water that would dissolve them again?

Salt cements are usually replaced after a short time by more durable cements (often calcite or dolomite, but sometimes quartz or chalcedony), and they shouldn't restrict water flow unless the rocks pores are completely full of cement, and the water is saturated with respect to the cementing mineralogy, making it unable to dissolve the cement.

Or (c) part of how rocks are eroded by rain.

Degree of cementation as well as cement mineralogy does play an important roll in the erosive process. A quartz or calcite-cemented rock will probably be more durable than a similar rock cemented by clays or salt, but this depends heavily on the weathering environment (rainforest, desert, etc.)

 

[Assyrian]

Thanks, I'll google some of the cements you mention

 

[Jazer]

You're projecting again, Jazer.

You are the one that can not answer a simple question about geological time scale. The ONLY question that really matters to most Creationists. That is why I am GAP I have no problem at all answering any question that has to do with the last 12,900 years. If I were OEC then maybe I would be as disfunctional as you are when it comes to answers & questions about the last 4.5 billion years. But as a PHd you are suppose to have all the questions and all the answers memorized.

I did look at the radiomatic thead. It is as big of a disaster as this thread is.

 

[Orogeny]

You are the one that can not answer a simple question about geological time scale. The ONLY question that really matters to most Creationists. That is why I am GAP I have no problem at all answering any question that has to do with the last 12,900 years. If I were OEC then maybe I would be as disfunctional as you are when it comes to answers & questions about the last 4.5 billion years. But as a PHd you are suppose to have all the questions and all the answers memorized.

I did look at the radiomatic thead. It is as big of a disaster as this thread is.

This thread isn't a disaster, Jazer. Everybody is behaving except you. The reason I'm not answering detailed questions about radiometric dating is because I don't want this thread to turn into the flamewar that one did. The question you've posed, how do we date deep time, was answered by both RickG and myself. Now as I've said, if you want a more detailed answer, bump the radiometric dating thread. Please stop trying to derail us.

 

[RickG]

You are the one that can not answer a simple question about geological time scale. The ONLY question that really matters to most Creationists. That is why I am GAP I have no problem at all answering any question that has to do with the last 12,900 years. If I were OEC then maybe I would be as disfunctional as you are when it comes to answers & questions about the last 4.5 billion years. But as a PHd you are suppose to have all the questions and all the answers memorized.

I did look at the radiomatic thead. It is as big of a disaster as this thread is.

Geologic strata is radiometrically dated. Is that not plain enough?

 

[Jazer]

Geologic strata is radiometrically dated. Is that not plain enough?

That is it? Period the end? Geologic strata is dated by radiometrically and radiometrically alone?

 

[Tiberius]

You have reason to doubt the validity of radiometric dating?

Please, then, describe in detail the process by which radiometric dating is flawed.

 

[TemperateSeaIsland]

I thought I read somewhere that the island was Viking (Norse). Are there Anglo & Saxons there also? Well I suppose there would be now a days. Anyways it gives me a good starting place to do some research. Tks.

The English use the Norse name. The Norse didn't settle here as the kingdom of Gwynedd who controlled the island wiped them out as they were raiding. The island is mostly Welsh with a little English and various other groups.

If you want to continue please PM me so this thread isn't further derailed.

 

[Jazer]

The Norse didn't settle here as the kingdom of Gwynedd who controlled the island wiped them out as they were raiding.

Wiped them out or sent them on their way to look for a place where the people were less able to defend themselves?

 

[Jazer]

You have reason to doubt the validity of radiometric dating?

I do not know anything about it. Although I read that some elements have a very short half life. So perhaps there were a lot more elements around in the beginning. I am GAP, we just deal with the last 12,900 years. The OEC would be the people to talk to about this sort of stuff.

 

[Orogeny]

You have reason to doubt the validity of radiometric dating?

Please, then, describe in detail the process by which radiometric dating is flawed.

If we're going to do this, bump the radiometric dating thread. Please don't pollute this one.

 

[Tiberius]

And some elements have a very long half life.

My advice is to not dismiss anything until you have learned about it.