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Author Topic:   Exploring the Grand Canyon, from the bottom up.
jar
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Message 156 of 283 (298994)
03-28-2006 12:58 PM
Reply to: Message 155 by roxrkool
03-28-2006 11:54 AM


Moving on.
Okay edited my summary. So we are through the Shinumo Layer and almost halfway through the Unkar Formation.

The next layer to consider is the Dox Formation. This one looks pretty complicated. What can you tell us about it?

This message has been edited by jar, 03-28-2006 12:21 PM


Aslan is not a Tame Lion

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jar
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Posts: 31281
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.9


Message 158 of 283 (299505)
03-29-2006 10:55 PM
Reply to: Message 157 by roxrkool
03-29-2006 10:39 PM


Exploring the Dox Formation.
Great intro. Can I get you to examine each section a bit, and following our progress from bottom to top.

The lowest layer is the Escalante Creek Member. At the bottom of it we find a material similar to the Sinumo Quartzite.

How do they tell the two apart? What is it that makes this a different layer?

Then on top of that we see shale and mudstone. We've talked about shale, but not mudstone. What is mudstone and what does mud stone tell us about the environment?


Aslan is not a Tame Lion

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jar
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Posts: 31281
From: Texas!!
Joined: 04-20-2004
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Message 160 of 283 (300344)
04-02-2006 4:58 PM
Reply to: Message 159 by roxrkool
03-31-2006 11:28 AM


Re: Exploring the Dox Formation.
Looking forward to that.

In the meantime, I have a couple general questions.

I understand that one thing with unconformities is that they are local or regional, what is missing in one location may be present in another.

Before the availability and capabilities of radiometric dating, was there anyway to estimate timespans? Or where things simply established as sequences?


Aslan is not a Tame Lion

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jar
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Posts: 31281
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Message 162 of 283 (300998)
04-04-2006 8:37 PM
Reply to: Message 161 by roxrkool
04-03-2006 2:39 PM


Re: Exploring the Dox Formation.
Okay trying to translate that to English.

Starting at the first level:

So there was a lagoon, that slowly filled up by a distributed mouth river system.

Is that correct?


Aslan is not a Tame Lion

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jar
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From: Texas!!
Joined: 04-20-2004
Member Rating: 2.9


Message 164 of 283 (301558)
04-06-2006 12:30 PM
Reply to: Message 163 by roxrkool
04-06-2006 12:18 PM


Re: Exploring the Dox Formation.
Okay, then on the next higher.

Here we seem to see more filling of the basin, and I get the feeling, form the description, of a series of slopes being created.

Is this a continuous process? Or are these a real series of discreet steps? From the description in Message 161:

Inferred sedimentary environment: distal turbidites. Following basin subsidence, which resulted in deeper water shale setting, terriginous sediment was occasionally cascading down the delta front as the delta was growing (in a basin-ward direction) and some of the sand and silt made it far enough to settle out atop the shale

it looks to me like we are now seeing larger particles settling out which implies that the flow is slower.

Is that correct?


Aslan is not a Tame Lion

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jar
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Message 171 of 283 (303008)
04-10-2006 6:13 PM
Reply to: Message 170 by roxrkool
04-10-2006 6:11 PM


Moving on
Sure, let's move on unless we need to do another updated summary.


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jar
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Joined: 04-20-2004
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Message 173 of 283 (305461)
04-20-2006 11:32 AM


what is the next member?
I'd like to try to work through the history of the Super Group at least in this thread.


Aslan is not a Tame Lion

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jar
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Message 175 of 283 (313534)
05-19-2006 12:37 PM


calling rox, petrophysics and other geologists.
Looks like folk really are reading what you're writing. I know I've learned a lot so far.

Please come out and play. I'll even let YOU have the ball!


Aslan is not a Tame Lion

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jar
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Message 182 of 283 (353426)
10-01-2006 10:11 AM


bump for more input.
To all our geologists, please help. So far we are still in the sub basement of the Grand Canyon and have miles to go before we sleep, miles to go. Our last glimpse was of the Dox formation and if someone could pick this up by explaining what happens between the Dox and the next higher layer I would appreciate it.


Aslan is not a Tame Lion

  
jar
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Message 183 of 283 (353711)
10-02-2006 5:31 PM


Calling our Geologists
We have gotten all the way up to the Dox formation. What is the next level?


Aslan is not a Tame Lion

  
jar
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Message 184 of 283 (356290)
10-13-2006 11:54 AM


bump for petrophysics
We have gotten all the way up to the Dox formation. What is the next level?


Aslan is not a Tame Lion

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jar
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Posts: 31281
From: Texas!!
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Message 186 of 283 (369109)
12-11-2006 5:52 PM
Reply to: Message 185 by roxrkool
12-11-2006 3:16 PM


for rox
Well, if you will return to teach me the least I can do is return to learn.


Aslan is not a Tame Lion

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jar
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Posts: 31281
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.9


Message 189 of 283 (400596)
05-15-2007 1:48 PM
Reply to: Message 188 by bdfoster
05-15-2007 12:58 PM


and now a word from ...
being an unmetamorphosed Precambrian basalt

I know "It's not easy being green", but what does "being an unmetamorphosed Precambrian basalt" mean?

Remember, we are trying to stay away from terms like "preCambrian" in this thread and simply deal with each layer and how each layer would have been formed.


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jar
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Posts: 31281
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.9


Message 192 of 283 (400619)
05-15-2007 6:28 PM
Reply to: Message 190 by bdfoster
05-15-2007 4:19 PM


But how was it formed?
We are holding off on the layer above until we determine all we can about the layer we are on.

You mention "supracrustal". That's yet another new term in this thread. Can you explain what that means?

And how does a geologist tell whether rock has been "metamorphosed"? How is this different than the intrusions found in the Vishnu Schist?

How thick is the Cardenas layer? Can we tell things like directionality? Are there signs of weathering or erosion and if so, what do they tell us? Is it all one lava flow or is it a series of events? If a series, how is that determined?

What do we know about the intersection of the lower Dox Sandstone and the Cardenas Lava Flow(s)?


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jar
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Posts: 31281
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.9


Message 196 of 283 (432963)
11-09-2007 10:45 AM


Bump for Antioch's Fire
Start at Message 1 sir.


Aslan is not a Tame Lion

  
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