olelog

The present wildfires in North Eastern Spain have an important thing in common with wildfires in California, namely katabatic winds. In California it is the “Santa Ana”. In Catalonia it is the Tramuntana, as it is called in Catalonian/Catalan, or Tramontane, as it is called in Spanish/Castellano. A katabatic wind is a wind that blows off a mountain system due to the cool denser air at altitude in the mountains sinking, and funnelling off into the coast. Katabatic is derived from the Greek word katabatikos (καταβατικός) meaning 'going downhill'.



The Tramuntana/Tramontana is a northerly wind which flows in the northeasternmost coast of Catalonia, at the Pyrenees border and a regular feature in mountainous northeast Spain (Catalonia) and its strong gusts, which can often exceed 160 kph, can spread fires rapidly across this heavily forested area.

• http://www.cbc.ca/news/world/story/2012/07/22/spain-wildfires.html
• http://www.dailymail.co.uk/news/article-2177519/Tragedy-Catalonia-Three-killed-24-injured-terrifying-wildfires-rage-north-eastern-Spain.html?ITO=1490

A newly found fossil of Sciurumimus albersdoerferi, which lived about 150 million years ago, provides the first evidence of feathered theropod dinosaurs that are not closely related to birds. The fossil is described in a paper published online on 2 July in the Proceedings of the National Academy of Sciences (PNAS). Because the new species sits deep within the evolutionary tree of theropods, the findings suggest that all predatory dinosaurs might have had feathers. In other words feathered dinosaurs might have been much more common than we thought. Down may also have been a special way of protecting baby dinosaurs. This may explain why they have not been found on adults.



This baby Sciurumimus, just about 70 cm long, was found in the limestones of northern Bavaria and preserves remains of a filamentous plumage, indicating that the whole body was covered with feathers. The genus name of Sciurumimus albersdoerferi refers to the scientific name of the tree squirrels, Sciurus, and means “squirrel-mimic”—referring to the especially bushy tail of the animal. The species name honors the two private collectors who made the specimen available for scientific study, Raimund og Birgit Albersdörfer.

The specimen of Sciurumimus is the most complete megalosauroid yet discovered and helps clarify significant anatomical details of this important basal theropod clade, such as the complete absence of the fourth finger.

Reference:
O. Rauhut et al. (2012)
Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany.
PNAS, published online 2 July 2012 (see abstract)
DOI:10.1073/pnas.1203238109

• http://www.pnas.org/content/early/2012/06/25/1203238109
• http://www.science20.com/news_articles/sciurumimus_albersdoerferi_dinosaur_feathered_theropod_not_related_birds-91672
• http://www.amnh.org/news/2012/07/newly-discovered-dinosaur-implies-greater-prevalence-of-feathers/

In Norwegian:
http://www.forskning.no/artikler/2012/juli/327055

On a Nordic geological winter meeting in Oslo in January 2010 Adam Garde told about a possible impact structure in Greenland (see my post). He and co-authors have now published further findings in a paper in Earth and Planetary Science Letters of 1 July 2012.

The so far oldest (i.e. 2975 million years) impact crater on Earth was found near Maniitsoq (in “my days” - and in Danish - known as Sukkertoppen) in West Greenland. It is the fourth multi-ring crater discovered on Earth, besides Chicxulub, Sudbury, and Vredefort. It is a 100 km-scale, circular structure in the Archaean North Atlantic Craton centred at 65°15′N, 51°50′W near the Maniitsoq town in the Qeqqata municipality in West Greenland. The structure comprises a set of highly unusual geological features that were created during a single event involving intense crushing and heating and are incompatible with crustal orogenic processes. The presently exposed features of the Maniitsoq structure were buried 20–25 km below the surface when this event occurred at about 3000 million years ago, during waning convergent orogeny. These features include: a large aeromagnetic anomaly; a central 35×50 km² large area of comminuted quartzo-feldspathic material; regional-scale circular deformation; widespread random fractures with featherlike textures; intense fracture cleavage; amphibolite–granite-matrix breccias unrelated to faulting or intrusions; formation and common fluidisation of microbreccias; abundant evidence of direct K-feldspar and plagioclase melting superimposed on already migmatised rocks; deformation of quartz by <c> slip; formation of planar elements in quartz and plagioclase; and, emplacement of crustally contaminated ultramafic intrusions and regional scale hydrothermal alteration under amphibolite-facies conditions. The diagnostic tools employed to identify impacting in the upper crust are inadequate for structures preserved deep within the continental crust. Nevertheless, the inferred scale, strain rates and temperatures necessary to create the Maniitsoq structure rule out a terrestrial origin of the structure.

Finding sufficient evidence was extremely hard because there is no obvious bowl-shaped crater left to find. Over the 3 billion years since the impact, the land has been eroded down to expose deeper crust 25 km below the original surface. All external parts of the impact structure have been removed, but the effects of the intense impact shock wave penetrated deep into the crust -- far deeper than at any other known crater -- and these remain visible. Because the effects of impact at these depths have never been observed before it has taken nearly three years of painstaking work to assemble all the key evidence. Only around 180 impact craters have ever been discovered on Earth and around 30% of them contain important natural resources of minerals or oil and gas. The largest and oldest known crater prior to this study, the 300 kilometre wide Vredefort crater in South Africa, is 2 billion years in age and heavily eroded. It has taken Adam Garde and his co-workers nearly three years to convince their peers in the scientific community that this is an impact structure, while the mining industry was far more receptive. A Canadian exploration company has been using the impact model to explore for deposits of nickel and platinum metals at Maniitsoq since the autumn of 2011.

Reference:
Adam A. Garde et al.
Searching for giant, ancient impact structures on Earth: The Mesoarchaean Maniitsoq structure, West Greenland
Earth and Planetary Science Letters
Volumes 337–338, 1 July 2012, Pages 197–210
http://dx.doi.org/10.1016/j.epsl.2012.04.026

• http://www.sciencedirect.com/science/article/pii/S0012821X12001938
• http://www.sciencedaily.com/releases/2012/06/120628164658.htm
• http://www.space.com/16366-oldest-meteorite-crater-earth-found.html
• http://www.linecom.com/space-vehicles/58188-oldest-impact-crater-on-earth-discovered-in-greenland.html
• http://www.sciencespacerobots.com/blog/62820124
• http://my.opera.com/nielsol/blog/maniitsoq-impact-structure

I cannot say that I am surprised, maybe rather relieved, that there is increasing evidence that bacteria play a key role in the formation of dolomite. For many years the formation of dolomite was a puzzle as dolomitization just didn’t work in the laboratory - well until somebody began to play around with bacteria. A new study presented in the journal Geology seems in fact to confirm the idea that sulphur-reducing bacteria are a key player.

A research team examined globally distributed marine bacteria that use sulphur compounds instead of oxygen to generate energy (i.e. sulphate respiration). They discovered that primary dolomite crystals are formed under conditions that are currently found in marine sediments. The dolomite precipitates exclusively within a mucus matrix, secreted by the bacteria to form biofilms. Different chemical conditions prevail within the biofilm compared to the surrounding water. In particular, the alteration of the magnesium to calcium ratio plays an important role. (The dolomitization principle is to take some limestone, which consists of calcite (CaCO₃) and add some Magnesium (Mg) to get dolomite CaMg(CO₃)₂)). The magnesium to calcium ratio changes allow for the formation of dolomite crystals. The team was able to show that the ratio of different isotopes of calcium between the ambient water, the biofilm and dolomite crystals is different. This ratio is an important tool to reconstruct past environmental conditions. The fact that bacteria are involved in this process allows more precise interpretations of climate signals that are stored in sediments.

A strong possibility is that massive primary dolomite can form particularly during times when large quantities of organic matter in the seabed are degraded by sulphate-respiring bacteria. Such conditions exist when the sea water above the seafloor is free of oxygen. In Earth's history, several such oxygen-free periods have occurred, partly consistent with time periods of intensified dolomite deposition.

Over 90% of (sedimentary) dolomite is made up of the mineral dolomite. Researchers became aware of large deposits of primary dolomite as old as 600 million years. Dolomite was first scientifically described in 1791 as a rock by Dolomieu from exposures in what are now known as the Dolomite Alps of northern Italy. Experts say the process of recent primary dolomite formation is restricted to extreme ecosystems, including bacterial mats in highly saline lakes and lagoons. As these systems are very limited in space, there is an explanation gap for geologists for the widespread presence of fossil dolomite.

• http://geology.gsapubs.org/content/early/2012/05/18/G32923.1
• http://cordis.europa.eu/fetch?CALLER=EN_NEWS&ACTION=D&SESSION=&RCN=34715

See also my post on Microbial Dolomite in Abu Dhabi [http://my.opera.com/nielsol/blog/2010/10/08/microbial-dolomite-in-abu-dhabi]

The finds of a new saurolophine dinosaur, Kundurosaurus nagornyi, are described in PlosOne. The new dinosaur was found in the Udurchukan Formation (Maastrichtian) of Kundur (at the Amur plateau in Eastern Russia), and represented by disarticulated cranial and postcranial material. All Kundurosaurus specimens were collected in the Kundur locality, hence the name.

The Kundur locality was discovered in 1990 and Large-scale excavations started at Kundur in 1999. In four sites dinosaur bone of different species form large bonebeds extending over several hundreds of m².

I gather you can guess why these types of dinosaurs are called Duck-Billed dinosaurs when you look at the following illustration from the new paper.



Notice the similarity of the head to that of modern ducks.

Reference:
Godefroit P, Bolotsky YL, Lauters P (2012)
A New Saurolophine Dinosaur from the Latest Cretaceous of Far Eastern Russia.
PLoS ONE 7(5): e36849.
doi:10.1371/journal.pone.0036849