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Blobrana


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Deccan Traps
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Two huge magma plumes fed the Deccan Traps eruption

Some 65 million years ago, the skies over India darkened as one of Earth's biggest volcanic eruptions burbled from below. It rumbled on for millions of years, blocking out sunlight and casting a chill globally, to produce what we know today as the Deccan Traps.
Many believe the eruption sent the dinosaurs into severe demise before an asteroid collision finally finished them off. But just how the Earth produced such vast volumes of lava (covering an area greater than the Australian states of New South Wales and Victoria combined) has remained a bit of a mystery. Now a new study by a pair of geologists in Canada shows that the eruption may have been fed by not one, but two deep mantle plumes.
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Blobrana


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Indian oil hunt discovers Deccan dinosaur destroyer

India's search for oil has revealed a geological club sandwich of fossils that scientists say is the first direct evidence for the theory that volcanic eruptions in western India caused the mass extinction that wiped out the dinosaurs.
Scientists from India, Switzerland and the US who studied tiny fossils sandwiched between volcanic layers beneath the Krishna-Godavari basin and the Bay of Bengal have discovered a pattern of declining fossil diversity that links the eruptions to the extinction.
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Blobrana


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RE: Shiva crater
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It was in the late 1960s that oil companies prospecting off India's western coast found something odd in the rocks beneath the ocean floor. Sediments laid down on an ocean bed over millions of years generally form rocks resembling a layer cake, with the layers getting older the deeper you delve. That was true in the boreholes drilled off the coast near Mumbai, to a point. But some 7 kilometres down, in a layer of rock deposited 65 million years ago, the neat progression abruptly stopped. Beneath it was a layer of shattered rock, followed by a layer of solidified volcanic lava up to 1 kilometre thick.
Something equally dramatic lurked onshore in the layered lava flows of the Deccan traps. These flows are interrupted by intermediate layers of sedimentary rocks, indicating that the volcanic activity that shook and remodelled the area from about 68 million years ago was not continuous. It was also not catastrophic; fossils found in the sedimentary layers suggest that dinosaurs had coexisted with this activity reasonably well.
But rooted in layers of lava dating from 65 million years ago - around the time dinosaurs disappeared from Earth's fossil record - are colossal spires of lava of a fundamentally different composition. These spires are up to 12 kilometres high and 25 kilometres across at their base, so that their tips appear as surface hills. The lava they are made of is highly alkaline and rich in iridium, an element rare in the Earth's crust but which commonly occurs in meteorites.
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Blobrana


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Sankar Chatterjee, the Bengali geoscientist who has ignited a debate around the world about an Indian link to the end of the dinosaur age, came to Lubbock from the centre of it all in Washington because he wanted to be closer to home: India.
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Prof. Sankar Chatterjee, in a paper presented at the Geological Society of America in Portland earlier this month, said this basin, a submerged depression on the west coast of India, is the largest crater. The 40-km wide crater is thought to have been formed by a meteorite that crashed into the Earth 65 million years ago. The meteorite was travelling at 58,000 miles per hour and was also responsible for killing dinosaurs that lived at that time, he claimed.

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Blobrana


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Title: The significance of the contemporaneous Shiva impact structure and Deccan volcanism at the KT boundary
Authors: CHATTERJEE, Sankar and MEHROTRA, Naresh M.

The Shiva crater is the largest hydrocarbon reserve in India, where the central uplift, the Bombay High, and the associated brecciated bodies and peripheral strata form ideal structural traps for oil and gas. The Shiva bolide (~40 km diameter) would generate lethal amount of kinetic energy of 1.45 x 1025 joules. The impact was so powerful that it led to several geodynamic anomalies: it fragmented, sheared, and deformed the lithosphere mantle across the western Indian margin and contributed to major plate reorganisation in the Indian Ocean.

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Blobrana


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A massive asteroid crashing off the western coast of India, creating the planet's largest known crater 40 km across, may have obliterated dinosaurs 65 million years ago, an Indian American has found.
Most of the crater lies submerged on India's continental shelf, in the area known as Bombay High. The impact appears to have sheared or destroyed much of the 48 km-thick granite layer in the western coast of India.

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Blobrana


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A mysterious basin off the coast of India could be the largest, multi-ringed impact crater the world has ever seen. And if a new study is right, it may have been responsible for killing the dinosaurs off 65 million years ago.
Sankar Chatterjee of Texas Tech University and a team of researchers took a close look at the massive Shiva basin, a submerged depression west of India that is intensely mined for its oil and gas resources. Some complex craters are among the most productive hydrocarbon sites on the planet. Chatterjee will present his research at this month's Annual Meeting of the Geological Society of America in Portland, Oregon.

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A US palaeontologist is challenging one of the fields greatest theories: the mass extinction of dinosaurs at the end of the Cretaceous period.
65 million years ago, a catastrophic event (or perhaps events) wiped out all large dinosaurs. This is a fairly well-established point of fact in the world of palaeontology. Besides the ancestors of birds and crocodiles, which survived, it has never been shown that large dinosaurs lived through the event.
But is that really the truth? Jim Fassett, a palaeontologist who holds an emeritus position at the U. S. Geological Survey, recently published a paper in Palaeontologia Electronica with evidence that points to a pocket of dinosaurs that somehow survived in remote parts of New Mexico and Colorado for up to a half million years past the end of the Cretaceous period.

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Title: An early India-Asia contact: Paleomagnetic constraints from Ninetyeast Ridge, ODP Leg 121
Authors: Chris T. Klootwijk, Jeff S. Gee, John W. Peirce, Guy M. Smith, and Phil L. McFadden

New paleomagnetic results from sedimentary rock and basement of the Ninetyeast Ridge (Ocean Drilling Program Leg 121, Sites 756-758) detail the northward movement of the Indian plate for the past 80 m.y. Analysis of the combined paleolatitude-age profile indicates a distinct reduction in India's northward movement rate at 55+ Ma, interpreted as completion of suturing of Greater India and Asia. India's northward motion slowed from 18-19.5 cm/yr to 4.5 cm/yr for the location of Site 758. Comparison of this profile with paleomagnetic data from the wider Himalayan region indicates that initial contact between northwestern Greater India and southern Asia was already established by Cretaceous-Tertiary time. This supports a possible causal link between the India-Asia convergence and the Deccan Traps extrusion.

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