A team led by Rolf Pedersen of the University of Bergen (Norway) has discovered the world's northernmost hydrothermal vent field. The black smokers are situated at 73° north on the Mid-Atlantic Ridge between Greenland and Norway, more than 220 kilometres from the previous northernmost vents found during a 2005 expedition, also led by Pedersen.

Other scientists have detected plumes of water from hydrothermal vents even farther north but have been unable to find the vent fields on the sea floor to image and sample them. The cluster of five vents discharge water as hot as approx. 300°C.

Read the complete story here.

- posted by Affenhänger @ 7/25/2008 12:15:00 AM 0 comments links to this post

A new, preliminary "Article" (CG2008 A06) version (the official release is scheduled for August 1st) was posted on July 17. [It is primarily a French version, BUT it comes with an abridged English version.]

Un nouvel "Article" (CG2008 A06) est en ligne en version préliminaire (la livraison officielle est prévue pour le 1 Août prochain). [Il est disponible qu'en version française ET en version anglaise courte.]

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Haddoumi H., Charrière A., Andreu B. & Mojon P.-O. (2008). - Middle Jurassic to Lower Cretaceous continental deposits from eastern High Atlas (Morocco): successive paleoenvironments and paleogeographic significance. - Carnets de Géologie - Notebooks on Geology, Brest, Article 2008/06 (CG2008_A06), 29 p., 7 figs., 4 pls. Format [HTML] or [PDF 2.069 KB]

Haddoumi H., Charrière A., Andreu B. & Mojon P.-O. (2008).- Les dépôts continentaux du Jurassique moyen au Crétacé inférieur dans le Haut Atlas oriental (Maroc) : paléoenvironnements successifs et signification paléogéographique.- Carnets de Géologie - Notebooks on Geology, Brest, Article 2008/06 (CG2008_A06), 29 p., 7 figs., 4 pls. Format [HTML] ou [PDF 2.069 KB]

Abstract: In the eastern High Atlas (Morocco), continental "Red Beds" overlying the last marine deposits of Jurassic age consist of three main lithostratigraphic units: the Anoual Formation, the Ksar Metlili Formation and the Dekkar Group, bounded by two sharp sedimentary discontinuities. The Anoual Formation is a fluvial-dominated deltaic plain deposit. It is followed by a final marine transgression of Early Bathonian age. The Ksar Metlili Formation found only in some subsident areas represents a renewal of fluvio-deltaic environments with a flora of Late Tithonian-Early Berriasian charophytes. The Dekkar Group occupies a larger area of sedimentation, its limits overlap the whole domain. From bottom to top, the succession indicates the existence of three paleoenvironments: alluvial fan deposits locally associated with Barremian?-Aptian lacustrine sediments containing charophytes and ostracods, alluvial plain deposits and finally, marine coastal to brackish plain deposits of the Cenomanian. (...)

Résumé : Dans le Haut Atlas oriental marocain, les "Couches rouges" continentales succédant aux dernières formations marines jurassiques sont organisées en trois grands ensembles lithostratigraphiques : la Formation d'Anoual, la Formation de Ksar Metlili et le Groupe de Dekkar, séparés par deux importantes ruptures de l'enregistrement sédimentaire. La Formation d'Anoual correspond à des dépôts de plaine deltaïque à dominante fluviatile, suivis d'une ultime incursion marine d'âge Bathonien inférieur. La Formation de Ksar Metlili est uniquement localisée dans certaines aires subsidentes et représente un deuxième cycle fluvio-deltaïque avec des charophytes d'âge Tithonien terminal-Berriasien inférieur. Le Groupe de Dekkar traduit l'installation d'une nouvelle aire de sédimentation recouvrant l'ensemble de la région avec trois environnements successifs : cônes alluviaux associés à une sédimentation lacustre du Barrémien?-Aptien à charophytes et ostracodes, puis dépôts de plaines alluviales, enfin plaines et lagunes côtières au Cénomanien. (...)

- posted by Affenhänger @ 7/23/2008 06:28:00 PM 0 comments links to this post

I found this Johns Hopkins University press release very interesting:

Mars once hosted vast lakes, flowing rivers and a variety of other wet environments that had the potential to support life, according to two new studies based on data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and other instruments on board NASA's Mars Reconnaissance Orbiter (MRO).

"The big surprise from these new results is how pervasive and long-lasting Mars' water was, and how diverse the wet environments were," says Scott Murchie, CRISM's principal investigator at the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md.

One study, published in the July 17 issue of Nature, shows that vast regions of the ancient highlands of Mars -- which cover about half the planet -- contain clay minerals, which can form only in the presence of water. Volcanic lavas buried the clay-rich regions during subsequent, drier periods of the planet's history, but impact craters later exposed them at thousands of locations across the planet.

The clay-like minerals, called phyllosilicates, preserve a record of the interaction of water with rocks dating back to what is called the Noachian period of Mars' history, about 4.6 billion to 3.8 billion years ago. This period corresponds to the earliest years of the solar system, when Earth, the moon and Mars sustained a cosmic bombardment by comets and asteroids. Rocks of this age have largely been destroyed on Earth by plate tectonics; they are preserved on the moon, but were never exposed to liquid water. The phyllosilicate-containing rocks on Mars therefore preserve a unique record of liquid water environments -- possibly suitable for life -- in the early solar system.

"The minerals present in Mars' ancient crust show a variety of wet environments," says John Mustard, a member of the CRISM team from Brown University in Providence, R.I., and lead author of the Nature study. "In most locations the rocks are lightly altered by liquid water, but in a few locations they have been so altered that a great deal of water must have flushed though the rocks and soil. This is really exciting because we're finding dozens of sites where future missions can land to understand if Mars was ever habitable and if so, to look for signs of past life."

A companion study, published in the June 2 issue of Nature Geosciences, finds that the wet conditions persisted for a long time. Thousands to millions of years after the clays were formed, a system of river channels eroded them out of the highlands and concentrated them in a delta where the river emptied into a crater lake slightly larger than California's Lake Tahoe, about 25 miles (40 kilometres) in diameter. "The distribution of clays inside the ancient lakebed shows that standing water must have persisted for thousands of years," says Bethany Ehlmann, another member of the CRISM team from Brown and lead author of the study of the ancient lake within Jezero Crater. "Clays are wonderful at trapping and preserving organic matter, so if life ever existed in this region, there's a chance of its chemistry being preserved in the delta."

CRISM's combination of high spatial and spectral resolutions-better than any previous imaging spectrometer sent to Mars-reveals variations in the types and composition of the phyllosilicate minerals. By combining data from CRISM and MRO's Context Imager (CTX) and High Resolution Imaging Science Experiment (HiRISE), the team has identified three principal classes of water-related minerals dating to the early Noachian period: aluminum-phyllosilicates, hydrated silica or opal, and the more common and widespread iron/magnesium-phyllosilicates. The variations in the minerals suggest that different processes, or different types of watery environments, created them.

"Our whole team is turning our findings into a list of sites where future missions could land to look for organic chemistry and perhaps determine whether life ever existed on Mars," says APL's Murchie.

APL, which has built more than 150 spacecraft instruments over the past four decades, led the effort to build CRISM, and operates the instrument in coordination with an international team of researchers from universities, government and the private sector. The Jet Propulsion Laboratory of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter mission for NASA's Science Mission Directorate. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft.

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There can surely be no doubt now that Mars hosted surface water for prolonged periods in its past. I personally doubt whether this made the environment hospitable enough, or was prolonged enough, to give rise to life. I would love to be pleasantly surprised.

- posted by Affenhänger @ 7/16/2008 06:21:00 PM 0 comments links to this post