Dinosaur-killing space rock ‘was a comet’

The impact 65 million years ago killed off 70% of species on Earth - including the dinosaurs

The impact 65 million years ago killed off 70% of species on Earth – including the dinosaurs

The space rock that hit Earth 65m years ago and is widely implicated in the end of the dinosaurs was probably a speeding comet, US scientists say.

Researchers in New Hampshire suggest the 180km-wide Chicxulub crater in Mexico was carved out by a smaller object than previously thought.

Many scientists consider a large and relatively slow moving asteroid to have been the likely culprit.

Details were outlined at the 44th Lunar and Planetary Science Conference.

But other researchers were more cautious about the results.

“The overall aim of our project is to better characterise the impactor that produced the crater in the Yucatan peninsula [in Mexico],” Jason Moore, from Dartmouth College in New Hampshire, told BBC News.

The space rock gave rise to a global layer of sediments enriched in the chemical element iridium, in concentrations much higher than naturally occurs; it must have come from outer space.

Extra-terrestrial chemistry

However, in the first part of their work, the team suggests that frequently quoted iridium values are incorrect. Using a comparison with another extraterrestrial element deposited in the impact – osmium – they were able to deduce that the collision deposited less debris than has previously been supposed …..
…. Read more at: http://www.bbc.co.uk/news/science-environment-21709229

Read also:
Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province
Terrence J. Blackburn et al
The end-Triassic extinction is characterized by major losses in both terrestrial and marine diversity, setting the stage for dinosaurs to dominate Earth for the next 136 million years. Despite the approximate coincidence between this extinction and flood basalt volcanism, existing geochronologic dates have insufficient resolution to confirm eruptive rates required to induce major climate perturbations. Here, we present new zircon U-Pb geochronologic constraints on the age and duration of flood basalt volcanism within the Central Atlantic Magmatic Province. This chronology demonstrates synchroneity between the earliest volcanism and extinction, tests and corroborates the existing astrochronologic time scale, and shows that the release of magma and associated atmospheric flux occurred in four pulses over ~600,000 years, indicating expansive volcanism even as the biologic recovery was under way….
http://www.sciencemag.org/content/early/2013/03/20/science.1234204

Particle physics research sheds new light on possible ‘fifth force of nature’

This picture depicts the long-range spin-spin interaction (blue wavy lines) in which the spin-sensitive detector on Earth’s surface interacts with geoelectrons (red dots) deep in Earth’s mantle. The arrows on the geoelectrons indicate their spin orientations, opposite that of Earth’s magnetic field lines (white arcs). (Credit: Illustration: Marc Airhart (University of Texas at Austin) and Steve Jacobsen (Northwestern University).)

In a breakthrough for the field of particle physics, Professor of Physics Larry Hunter and colleagues at Amherst College and The University of Texas at Austin have established new limits on what scientists call “long-range spin-spin interactions” between atomic particles. These interactions have been proposed by theoretical physicists but have not yet been seen. Their observation would constitute the discovery of a “fifth force of nature” (in addition to the four known fundamental forces: gravity, weak, strong and electromagnetic) and would suggest the existence of new particles, beyond those presently described by the Standard Model of particle physics….
Read more: http://www.sciencedaily.com/releases/2013/02/130221192736.htm

New clues to the early Solar System from ancient meteorites

 In order to understand Earth’s earliest history–its formation from Solar System material into the present-day layering of metal core and mantle, and crust–scientists look to meteorites. New research from a team including Carnegie’s Doug Rumble and Liping Qin focuses on one particularly old type of meteorite called diogenites. These samples were examined using an array of techniques, including precise analysis of certain elements for important clues to some of the Solar System’s earliest chemical processing. Their work is published online July 22 by Nature Geoscience….
Read more at: phys.org

Could GPS be used to predict earthquakes?

Professor Kosuke Heki of Hokkaido University in Japan believes he has found a way to predict earthquakes.
Heki analyses GPS signals by measuring the TEC, or Total Electron Content, in the upper atmosphere. Whilst measuring how the TEC was disrupted by sound waves after the Tohoku earthquake of 2011, he discovered – quite by accident – that the TEC was also disrupted in the 40 or so minutes before it.
Going back through GPS records he has found similar correlations for other major earthquakes, a discovery that is being heralded as a major breakthrough in our understanding of earthquake phenomena.
See the relevant video here: www.bbc.co.uk

Laguna del Maule

In the Andean mountain range, stretching across the border between Chile and Argentina, lies a volcanic caldera named Laguna del Maule, roughly 15 by 25 kilometers (9 by 15 miles) across. Within the northern part of the caldera lies Maule Lake, which is surrounded by a complex volcanic landscape.

This perspective image is made from data acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite on April 9, 2003. ASTER produces images using infrared, red, and green wavelengths of light. In this image, vegetated areas range in color from red to pink, snow is white, water is black, and bare rock is earth-toned.

Laguna del Maule holds an assortment of volcanic features, including small stratovolcanoes, lava domes, and cinder cones. Some of the most prominent features surrounding Lake Maule are lava flows. Some of those lava flows protrude into the lake, looking a little like dough spreading under its own weight.

Volcanologists estimate that volcanoes at this site have been active over the past 10,000 years, but the date of the last eruption at Laguna del Maule is unknown.
Read more: earthobservatory.nasa.gov

‘New metal type’ at Earth’s core

The precise chemistry of metals within the Earth's interior will dictate the nature of its magnetic field

The composition of the Earth’s core remains a mystery. Scientists know that the liquid outer core consists mainly of iron, but it is believed that small amounts of some other elements are present as well. Oxygen is the most abundant element in the planet, so it is not unreasonable to expect oxygen might be one of the dominant “light elements” in the core. However, new research from a team including Carnegie’s Yingwei Fei shows that oxygen does not have a major presence in the outer core. This has major implications for our understanding of the period when the Earth formed through the accretion of dust and clumps of matter. Their work is published Nov. 24 in Nature.

According to current models, in addition to large amounts of iron, the Earth’s liquid outer core contains small amounts of so-called light elements, possibly sulfur, oxygen, silicon, carbon, or hydrogen. In this research, Fei, from Carnegie’s Geophysical Laboratory, worked with Chinese colleagues, including lead author Haijun Huang from China’s Wuhan University of Technology, now a visiting scientist at Carnegie. The team provides new experimental data that narrow down the identity of the light elements present in Earth’s outer core.

With increasing depth inside the Earth, the pressure and heat also increase. As a result, materials act differently than they do on the surface. At Earth’s center are a liquid outer core and a solid inner core. The light elements are thought to play an important role in driving the convection of the liquid outer core, which generates the Earth’s magnetic field.

Scientists know the variations in density and speed of sound as a function of depth in the core from seismic observations, but to date it has been difficult to measure these properties in proposed iron alloys at core pressures and temperatures in the laboratory.

“We can’t sample the core directly, so we have to learn about it through improved laboratory experiments combined with modeling and seismic data,” Fei said.

High-speed impacts can generate shock waves that raise the temperature and pressure of materials simultaneously, leading to melting of materials at pressures corresponding to those in the outer core. The team carried out shock-wave experiments on core materials, mixtures of iron, sulfur, and oxygen. They shocked these materials to the liquid state and measured their density and speed of sound traveling through them under conditions directly comparable to those of the liquid outer core.

By comparing their data with observations, they conclude that oxygen cannot be a major light element component of the Earth’s outer core, because experiments on oxygen-rich materials do not align with geophysical observations. This supports recent models of core differentiation in early Earth under more ‘reduced’ (less oxidized) environments, leading to a core that is poor in oxygen.

“The research revealed a powerful way to decipher the identity of the light elements in the core. Further research should focus on the potential presence of elements such as silicon in the outer core,” Fei said.

carnegiescience.edu – bbc.co.uk

Super-Powerful X-Ray Beam Will Probe the Center of the Earth

Beamline Sample This image shows the heating of a catalyst sample in an "in situ" cell at actual operating conditions. The catalyst is studied using time-resolved X-ray absorption spectroscopy. A new beamline at the European Synchrotron Radiation Facility has a resolution of a few microseconds. ESRF

It is much easier to get to Mars than to get deep inside this planet, so for all our knowledge about things like earthquakes and the magnetic field, Earth’s interior is actually very poorly understood. To study how metals interact at the prodigious pressures within, scientists squeeze small particles in the lab and heat them up — but this is an inexact science and difficult to do. A newly revamped X-ray beam facility in Europe may be able to improve matters, and shed some light on just what is going on at the center of our planet.
The European Synchrotron Radiation Facility inaugurates its new ID24 beam today, in preparation for experiments next spring. It will enable scientists to exact extreme pressures and temperatures on metals, aiming to understand how they act at Earth’s core. It will also be able to study new chemical catalysts and battery technology, among other atomic reactions.
A synchrotron is a type of particle accelerator — the Tevatron is one — that can be used for a wide range of applications. One such application involves harnessing the accelerated particles’ electromagnetic radiation for scientific imaging. Synchrotron light sources use a series of magnetic fields to bend this radiation into different wavelengths of light. At ESRF, beamlines branch off from the particle acceleration ring to capture the particles’ (usually electrons) radiation. The new beamline, ID24, will enable incredibly fast X-ray absorption spectroscopy.
This works by firing an intense X-ray beam at a sample, and watching how atoms of the different elements inside the sample absorb the X-rays — it’s an active probe, monitoring its own experiments. The beamline has an array of germanium detectors that can take 1 million measurements per second, according to an ESRF news release. So scientists could take a small sample of iron, put it in the beamline, heat it to 10,000 degrees, and watch what happens. This would conceivably help scientists understand how iron behaves 1,500 miles beneath the surface of the Earth, and what are the melting points of other metals present in the mantle and core. This, in turn, could shed some light on things like Earth’s dynamo, which creates its magnetic field.
The ID24 beam is the first of eight new beamlines at ESRF, part of a $245 million (180 million Euro) upgrade.
http://www.popsci.com