Monday, September 27, 2010

monkey, monkey, where for art thou monkey

Iyad Zalmout was born in Syria. He developed a love for geology growing up in the mountains collecting fossil gastropods and bivalves to show his friends - this later morphed into collecting lizards and snakes to scare his class mates. Iyad completed his PhD at the University of Michgan with Phil Gingrich on "Late Eocene sea cows (Mammalia, Sirenia) from Wadi al Hitan in the Fayum Basin, Egypt" and has stayed as a Post-doc in the Exhibit Museum.

A year ago Iyad was looking for whale fossils in a presumed to be section of marine sediments when he began to discover terrestrial mammal fossils. He was amazed to discover what is problably the last common ancestor of apes and monkeys before the two lineages separated. With a major discovery like this, press releases were made both by the publishing journal Nature and the University of Michigan. The reading this week will be the paper published in Nature.

Slide show of the primate fossils
Nature Video

Monday, September 20, 2010

Hydrothermal activity blasts out sediment

Ted Moore is an Emeritus Professor in the Department of Geological Sciences at the University of Michigan. This position is given to a professor who has retired but is highly regarded by the department. With this title Ted has some office and research space which allows him to continue research, which he has very actively. Since he retired he has sailed on research cruises, completed lecture tours and written papers. Ted was a pioneer in the field of paleoceanography and was integral to a massive community-based research initiative called CLIMAP, whose purpose was to map out the temperatures on the planet during the last ice age, 21 thousand years ago. Ted has a speciality in micropaleontology looking a a zooplankton group known as radiolaria. Radiolaria are a amoeboid protozoa that produce intricate skeletons made of silica.

Image of radiolaria from Nest Labs at the University of Dayton.

Ted will be talking about the sediments that are deposited in the equatorial region and their interaction with hydrothermal fluid. The classic hydrothermal vent in the ocean is associated with volcanism at mid ocean ridges (sea floor spreading centers at divergent boundaries). However a recent estimate (Bekins et al. 2007 - in resources) suggests that hydrothermal fluids exiting outcrops (cliffs) of basement (meaning the rock underlying sediment) sea floor (basalt generated at mid ocean ridges) may account for 75% of the hydrothermal outflow in the equatorial Pacific. These environments have become the focus of interest by scientist interested in microrganisms - these environments maybe similar to those found on other planets and the work these microrganisms do might be very important to the formation of mineral deposits.

Cartoons illustrating the development of pits over a bedrock outcrop. (a-c) show where flanking basins have approximately the same thickness of fill and (d-f) show where the basin fill is asymmetrical.

Ted came up with the model by which pits form in deep sea sediments allowing the discharge of waters circulating through the ocean crust. This water is able to remove heat from the cooling newly formed ocean plate explaining the low heat of the equatorial Pacific plates. The model suggests that the sediments overlaying the bedrock outcrop are dissolved by the water being discharged leaving behind sediment pits. These hydrothermal discharges may also be involved in the diagenetic alteration of siliceous sediments such as those which form from the remains of radiolaria. At high temperatures the silica remains of organisms convert to porcelanite and chert as the crystal structure of the opaline or biogenic silica changes.

Chert or jasper in the jasper conglomerate outside the CC Little building

Friday, September 10, 2010

Bedrock rivers and active deformation

Brian Yanites is a Post-doctoral Researcher in the Department of Geological Sciences at the University of Michigan. Brian did his PhD in Boulder at the University of Colorado with Greg Tucker.

Brian is interested in geomorphology - geologic research tries to understand the origin of the landforms (mountains, rivers etc) on Earth. On his web page he says he is trying to answer two fundamental questions: 1) How do local processes interact to form landforms and landscapes? and 2) How can we, as researchers, appropriately model and constrain these processes to explore the long-term evolution of the earth’s surface?

On Friday Brian will be talking about how to use river incision to understand deformation. Let's break that down. River incision refers to a river eroding downward through its riverbed which may be made of sediment or bedrock.The river begins at a higher elevation and incises or cuts or erodes downward through the bed it flows over. The river may leave its floodplain behind at a higher elevation of it may be lowered at the same time. Deformation refers to changes in the shape or volume of a rock body. Stress/pressure is often applied to rock bodies by plate tectonics for example. Rock bodies may bend in a ductile fashion (forming anticlines or synclines) or in a brittle fashion (faults that fracture rock bodies).

Rail lines outside Christchurch, New Zealand deformed in a ductile fashion in response of the earthquake of September 3rd 2010 (photo by Ian McGregor).

As the rock body under a river deforms, the river bed responds by becoming steeper (the elevation change down the river bed increases) and the width of the river bed becomes narrower (less distance between either side of the river bank). Both responses cause the river to become more erosive and the river will incise or cut down through its river bed faster. If the age of the beginning of the incision/cutting down is known, then the geomorphologist can calculate how quickly the river is eroding its bedrock.

Brian will be talking about rivers that drain off the Tibetan plateau. He has calculated how fast the rivers are incising the landscape by dating the time when incision began. Brian has used known earthquakes events as well as optically stimulated luminescence (OSL) dating techniques to calculate when the river sediments last saw sunlight to date the beginning of incision. Using his results Brian has helped us further understand the tectonics that are actively shaping our planet.

You can read more about these techniques at 'Rivers crossing growing folds' or in the Yanites folder in resources on Ctools.

Wednesday, September 8, 2010

Introductions: September 10 2010

New faculty, postdoctral researchers and graduate students will be introduced in this weeks Smith Lecture. There will be no lecture discussion as a result.