VOLCANO MADNESS: Re: [Geology2] Before the end

Saturday, August 27, 2011

Re: [Geology2] Before the end

Yup. Really, really big.

Lin

On Sat, Aug 27, 2011 at 12:01 AM, Kim Noyes <kimnoyes@gmail.com> wrote:

This is BIG!

On Fri, Aug 26, 2011 at 4:03 PM, Lin Kerns <linkerns@gmail.com> wrote:

Photo Credit: Thomas Tobin Scientists Peter Ward and Joe Kirschvink use a paleomag drill to extract an ammonite fossil from the side of a hill during their expedition to a series of islands off the Antarctic Peninsula. The researchers believe they found evidence of a minor extinction prior to the one that killed the dinosaurs 65 million years ago.

Before the end

Scientists find evidence of extinctions prior to impact event that killed the dinosaurs

By Peter Rejcek, Antarctic Sun Editor

Posted August 12, 2011

Few topics in science are as hotly debated as the extinction of the dinosaurs 65 million years ago.

However, evidence continues to pile up in favor of the theory first put forth more than 30 years ago that an asteroid impact on Earth dealt a geologically swift blow to the Earth's dominant fauna.

But a team of National Science Foundation -funded scientists suggests there was at least one "pre-cursor" extinction under way more than 100,000 years before a giant space rock hit the planet — an event known as the K-Pg extinction for when the Cretaceous period ended and the Paleogene began.

The claim comes after four expeditions in as many years to islands off the Antarctic Peninsula, where researchers recovered well-preserved fossils from a stretch of sediments that afforded them a high-resolution look back in time.

"A number of different species all went extinct at one interval prior to the actual boundary," said Thomas Tobin, a PhD student at the University of Washington in Seattle and lead author on a recently submitted paper about the pre-cursor extinction.

The creatures that went extinct were invertebrates such as snails and clams, according to Peter Ward , with the University of Washington in Seattle and co-principal investigator on the project.

Photo Credit: Sarah Slotznick

Scientists Joe Kirschvink, left, and Chris Thissen examine the K-Pg boundary on Seymour Island.

Photo Credit: Sarah Slotznick

Shane Schoepfer, Kelly Hillbun and Thomas Tobin on Snow Hill Island, with Cockburn Island in the background.

Photo Credit: Thomas Tobin

The team's field camp on Vega Island during a snowstorm.

"We're seeing two very different types of extinctions going on," Ward said, explaining that the pre-cursor extinction appeared limited to benthic organisms, critters living on the ocean floor. He believes the world underwent a rapid global warming event that eventually affected ocean circulation so that the waters stratified, making the bottom layers anoxic. No oxygen — no life.

They say the link is a major volcanic event — or series of events — that occurred roughly around the same time in an area known as the Deccan Traps in India. Formed between 60 and 68 million years ago from a series of volcanic eruptions, the Deccan Traps consist of multiple layers of solidified volcanic basalt. The massive release of volcanic gases, particularly carbon dioxide, from the eruptions may have created a greenhouse effect.