Ž . Gabbroic sills intruding dunite in the crust–mantle transition zone MTZ of the Oman ophiolite have textures and compositions very similar to those in modally layered gabbros that form the lower part of the gabbro section in the ophiolite, and different from those in non-layered gabbros near the dike–gabbro transition. The presence of gabbroic sills in the MTZ indicates that modally layered ...

[1] A new magnetic map of the Moon, based on Lunar Prospector magnetometer observations, sheds light on the origin of the South Pole-Aitken basin (SPA), the largest and oldest of the recognized lunar basins. A set of WNW-trending linear to arcuate magnetic features, evident in both the radial and scalar observations, covers much of a 1000 km wide region centered on the NW portion of SPA. The so...

The timescale of the modification stage basin-sized impact structures is not well understood. Owing to ca. 10 km erosion since its formation, Vredefort structure, South Africa, an ideal testing ground for deciphering post-impact modification. Here, we present geophysical and geochemical evidence from Granophyre Dikes, which were derived - now eroded melt sheet. dikes have been studied mostly in...

[1] Valles Marineris represents the deepest natural incision in the Martian upper crust. Previous studies showed that the upper parts of the walls were made of finely layered probable basalts in most of the chasmata, while the base of the stratigraphy reveals primary Noachian crustal blocks. Exposures of pristine Noachian bedrock are rare on Mars, and mostly observed outside of their geological...

Dike emplacement in volcanic rift zones is often associated with the injection of “bladelike” dikes, which propagate long distances parallel to the rift, but frequently remain trapped at depth and erupt only near the tip of the dike. Over geologic time, this style of dike injection implies that a greater percentage of extension is accommodated by magma accretion at depth than near the surface. ...

The vulnerability of buildings on coastal dikes due to overtopping wave impacts is difficult to assess. A method is developed in this paper to quantify the vulnerability of masonry buildings on a coastal dike exposed to wave overtopping. Using previous studies, the accidental loads due to the extreme wave impacts are characterized. Using the approach from Eurocode 6, the strength of masonry bui...

Three large scale field tests on dikes have been carried out at the IJkdijk test site in the Netherlands. Two tests involved piping, micro-instability of the sand core and erosion from overtopping. Both dikes failed on micro-instability. The third test involved slope stability with a deep sliding plane. All tests were done to validate monitoring systems and dike safety information systems. Seve...

HUA LI. Countermeasures against Scour at Bridge Abutments (Under the direction of Dr. BRIAN D. BARKDOLL) Scour at bridge abutments can cause damage or failure of bridges and result in excessive repairs, loss of accessibility, or even death. To mitigate abutment scour, both clear-water and live-bed laboratory experiments in a compound channel were performed using parallel walls and spur dikes as...