Skip to comments.The big picture: 65 million years of temperature swings
Posted on 02/26/2010 10:45:29 PM PST by Ernest_at_the_Beach
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But around 65 million years ago there were massive outpourings of lava in India (see Deccan Traps). And very high CO2 levels, many times higher than today. Also the KT (”dinosaur killer”) asteroid impact occurred around that time, which also may have contributed large amounts of CO2 to the atmosphere. Again, much higher levels than we have today.
“Greenhouse Crisis. [due to KT asteroid impact, ~65 million years ago -etl] Impact with the carbonate-rich rocks of the Gulf coast releases large amounts of CO2, initiating a greenhouse warming. Note that this would offset the proposed impact winter effects [’soot’, etc, blocking sunlight -etl].”
“The Deccan Traps formed between 60 and 68 million years ago, at the end of the Cretaceous period. The bulk of the volcanic eruption occurred at the Western Ghats (near Mumbai) some 66 million years ago. This series of eruptions may have lasted fewer than 30,000 years in total. The gases released in the process may have played a role in the CretaceousTertiary extinction event, which included the extinction of the non-avian dinosaurs.”
“The Deccan volcanism, at 64-65 Ma: The second event of this phase is the Deccan volcanism which occurred after a hiatus of 30 Ma. Also, after exactly the same hiatus, and at the same time of 64-65 Ma, the Indian plate experienced breakup from yet another partner at Gondwanaland time the Seychelles. This probably indicates that the second stage of magmatism, which began at 93 Ma, was controlled by the breakup events between Gondwanaland microplates and the Indian plate. Also, it shows that the breakup process was a gradual and progressive phenomenon, starting with Madagascar-India separation and, after another 30 My, Seychelles-India separation. Since this process controlled West Coast magmatism, which tectonism is expected to do, we deduce that the magmatism was also progressive. Thus, we conclude that (i) the rhyolitic volcanism at 93 Ma resulted from Madagascar-India breakup, and (ii) that this breakup event was a continuous process which led to Seychelles-India breakup after another 30 My and to Deccan volcanism at the same time. The progressive chemical trend of the volcanics, i.e., from rhyolite to basalt, indicates gradual progressive increase in temperature and/or gradual progressive lowering of the liquidus in the magma chamber as a result of gradual progressive rifting/breakup of the Indian plate with Madagascar and the Seychelles respectively.
The shift from plutonism during first phase to volcanism during the second phase perhaps indicates the presence of direct, uninterrupted conduits from the magma chamber to the surface of the continental crust during the second phase. This is what is expected during extensive rifting events such as Madagascar-India and Seychelles-India separation which did not occur during the first phase.
The large volume of the Deccan volcanics and the high rate of volcanism during the Deccan episode indicate:
1. higher rate of adiabatic decompression due to continental scale rifting,
2. consequently, higher rate of melting of magma in the chamber,
3. further, continental delamination of the western continental crust due to elevation in temperature and decrease in viscosity caused by the presence of a heat source in the form of a magma chamber at its base, and
4. a direct plumbing system between the melt and the surface, during eruption.
Considering that the West Coast and Narmada-Tapi rift zones were reactivated at the time of Deccan volcanism and the Cambay and Kutch rifts were also available as direct conduits for the upward movement of melt, we infer that the presence of these four rifts and geophysical evidence of lithosphere thinning beneath the westen coast explains the size, volume and eruption rate of the Deccan volcanics.
The geochemical variation within the Deccan volcanics, as mentioned above, perhaps indicates differences in the chemistry of the host rocks. For example, along the Narmada-Tapi rift zone the magmatic melt must have interacted with the host sediments, which are Mahakoshal Jurassics along with Archean metamorphics. Similarly along the West Coast, Cambay and Kutch rifts, the melt would have interacted with Archean-Precambrian metamorphics. Consequential changes in the chemistry would be reflected in the geochemistry of the DVP volcanics.”
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'Are we headed for an ice age?'
Simple answer, YES.
I'm a 'science junky'. It prolly has something to do with my profession where I work with the Laws of Physics everyday and 'a' + 'b' always = 'c', and 'X' x 'Y' always = 'Z'. And no guessing or 'computer modeling' is required to 'prove' that E=mc2 works every time.
And as a science junky, in my spare time I watch the Science Channel like addicts chase their next fix. And the 'SC" has numerous series on the Earth and our Climate. They're directly related, climate specific, or as a byproduct of some series on our Solar System and/or Cosmology.
Long story short;
We are coming OUT of a naturally occurring warming period, and entering a naturally occurring Cooling Period. These cyles have repeated and repeated since our present Earth, ver 2.0, was created along with the moon approx 4.5 Billion years ago.So. Are we headed for an ice age? You betcha(1). Unfortunately these Real Scientists can't predict when, as in how soon, it will happen.
During this time we've even had periods called 'Ice Ball Earth' where the Earth was like one 'HUGH' snowball. Every spot, even at the equator, was covered in snow or ice. Scientists (real ones /s), know of one period of Ice Ball Earth' for positive and there's evidence that it may have happened twice.
(1) Al Gore, please pick up the Red Courtesy Phone.
Ding! Ding! Ding! We have the winning post of the day.
Everybody back away from your keyboards, and try again tomorrow...
I popped my head out the door about an hour ago. Still damn cold out there. Nice graphs. I book marked the GISP2 site for later investigation.
There is a place in northwest Oregon called Mist. Very, very small town; outside of town is an Elk Preserve. My reason for mentioning this place is the seashells preserved in the ground thereabouts, exposed in stream beds due to erosion.
Eight thousand years ago an arm of the sea reached far inland at that locale. During that time the sea level along the Oregon coast was 15 feet higher than it is today. Fifteen thousand years ago the sea level was much lower than today; in fact, you would have to go about 24-26 miles further west of the present coastline to reach the Ice Age coastline (15,000 before present) of Oregon.
Yes, it is getting colder.
65 million? Me thinks there are a few too many zeroes in that numbah. How about 6,500 years, the age of God’s Earth
Imagine all of the corruption that would be dead and buried too! I hope it gets down to D.C. We need a shot at a do over, IMHO.
And you are correct because......
You’re right, thank you for the correction, I appreciate it. God’s Earth is only 6,013 years old (as of last October.)
We may not:
Greenland GISP2 Ice Core -Last 10,000 Years
What is the relevance of the years listed before present,
they are unevenly spaced.
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