From: bivalve (bivalve@mail.davidson.alumlink.com)
Date: Mon Nov 17 2003 - 16:24:04 EST
>OK, I'll bite. What caused the global oceanic circulation to shut down? <
The key factor distinguishing different bodies of water in ocean circulation is difference in density. This is primarily impacted by temperature and salinity. If there was no place near the ocean surface where relatively dense water was generated (high evaporation or low temperature, preferably forming ice) and able to sink, circulation would be a lot slower. Surface to bottom mixing is particularly important.
Even with the relatively vigorous circulation today, there are large areas of low oxygen, so the balance between circulation and organic input is crucial. The annual dead zone in the Gulf of Mexico reflects anoxia due to the high levels of organic material coming down the Mississippi (including stuff that promotes plankton blooms in the Gulf); it lasts until enough hurricanes come through to stir things up again. Likewise, the North Pacific, currently the end of the line for ocean circulation, would be relatively easy to turn anoxic, though my paleoceanograhy professor was exaggerating when he suggested that a bunch of dead whales would push it over.
>Incidentally Glenn, one of your arguments against transported organics forming coal was that currents would carry the organics out to sea, and therefore coal must have formed from swamps in situ. Since we know that plankton are marine and therefore transported before they were deposited, then by analogy the peat that formed coal could also have been transported before deposition. The principle is the same.<
I think Glenn was arguing against the global flood model, which ought to put coal out in the ocean basins (which we don't see), rather than the impossibility of any transport. However, the plankton are probably not transported significantly away from their point of origin; currents will move them as they sink, but they would be in the general vicinity of origin.
>I saw on some YEC video that oil is forming today in the Gulf of California. They showed underwater a drop of oil as it escaped from the bottom and floated up in the water. The message was that oil is not difficult at all to form under the right conditions.<
The situation in the Gulf of California combines rapid deposition and burial with thermal energy associated with the spreading center. As a result, organic material is rapidly cooked into oil. In contrast, I believe there are some Precambrian hydrocarbon source rocks in Australia where the material has remained at very low temperatures, near the surface, over hundreds of millions of years, very gradually cooking. The YEC misuse of this that I have encountered is to claim that, because it is possible under the right conditions to form oil relatively rapidly, therefore all oil formation is explained within a young-earth framework. Although the Gulf of California oil is forming rapidly from a geologic viewpoint, I doubt that it is forming quickly enough for a young-earth view (at this particular locality). Certainly the fact that oil is currently escaping the seafloor somewhere tells us nothing about the rate of formation.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487-0345 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
---------- Original Message ----------------------------------
From: bpayne15@juno.com
Date: Sat, 15 Nov 2003 20:52:08 -0600
>On Fri, 14 Nov 2003 08:44:32 -0600 "Glenn Morton"
><glennmorton@entouch.net> writes:
>
>GRM: I don't see any connection at all. Producing plankton is easy,
>preserving it is the difficult thing. The current idea on the oceanic
>anoxic events (OAE) is that the global oceanic circulation shut down,
>depriving the deep ocean of oxygen.
>
>OK, I'll bite. What caused the global oceanic circulation to shut down?
>I can't imagine any configuration of the continents which would shut off
>all circulation. I guess if North America and Europe were joined, that
>would cut off the cold polar water from the North Atlantic which would at
>least slow circulation in the Atlantic in the northern hemisphere. I
>think temperature differences are what drives the circulation?
>
>At any rate, Art suggested that the marine blooms depleted the oceanic
>oxygen supply, and also supplied the skeletons to form the chalk deposits
>such as we see at Dover, England and the equivalent in south Alabama.
>
>Thus any dead plankton which fell to the bottom was preserved and buried
>by later plankton which fell on top of them. The widespread nature of
>these OAE's can be shown by the fact that the Eagleford Shale in Texas,
>an organic rich shale, is the very same shale as the Plenus Marl in Great
>Britain, and the source rocks which generated most of the oil in the Gulf
>of Mexico, is Oxfordian and Kimmeridgian in age, the same as the source
>for the oils offshore Nova Scotia and the oil in the NOrth Sea.
>
>Art's suggestion is great for creating organic matter, but one then has
>to collect it, cook it and turn it into oil and that is much more
>difficult (especially the collecting part since currents carry it away).
>
>Don't forget, if the OAE was in effect, there may have been shallow,
>landlocked seas. Since we know that plankton (or something) DID collect
>in the organic-rich shales, then we know that there must have been either
>low current flow, or production was high and the currents only spread the
>organics over a wide area within the landlocked sea.
>
>Incidentally Glenn, one of your arguments against transported organics
>forming coal was that currents would carry the organics out to sea, and
>therefore coal must have formed from swamps in situ. Since we know that
>plankton are marine and therefore transported before they were deposited,
>then by analogy the peat that formed coal could also have been
>transported before deposition. The principle is the same.
>
>His suggestion doesn't really have anything to do with actually creating
>oil which is more than CH2, which is Methylene and is not a stable
>product. My suspicion is that the energy used to separate out the .
>methylene would be more than its energy content.
>
>I saw on some YEC video that oil is forming today in the Gulf of
>California. They showed underwater a drop of oil as it escaped from the
>bottom and floated up in the water. The message was that oil is not
>difficult at all to form under the right conditions. We may not know
>what those conditions were, but we do know that oil formed somehow,
>regardless of our ignorance as to the process. Understanding the process
>isn't important in this context. The question is how do we generate the
>organics for the process to convert to oil.
>
>Bill
>
This archive was generated by hypermail 2.1.4 : Mon Nov 17 2003 - 16:24:30 EST