Another one from the Suez Rift. This is my former colleague Chris Ott (hi Chris!), standing in front of a syn-rift boulder conglomerate containing various pre-rift and syn-rift clasts (the one to the right of Chris is probably a Precambrian basement basalt clast). These are actually some of the smaller clasts in the conglomerate: lower down in the same unit there are limestone blocks that are several tens of metres across, which makes mapping in the area "interesting". The unit is in the steeply dipping limb of a fault-propagation syncline in the hanging wall of a major block-bounding normal fault that was active during deposition. It is interpreted as a debris flow triggered by slope collapse.
Showing posts with label Image of the week. Show all posts
Showing posts with label Image of the week. Show all posts
Friday, 19 September 2008
Image of the week #3
Another one from the Suez Rift. This is my former colleague Chris Ott (hi Chris!), standing in front of a syn-rift boulder conglomerate containing various pre-rift and syn-rift clasts (the one to the right of Chris is probably a Precambrian basement basalt clast). These are actually some of the smaller clasts in the conglomerate: lower down in the same unit there are limestone blocks that are several tens of metres across, which makes mapping in the area "interesting". The unit is in the steeply dipping limb of a fault-propagation syncline in the hanging wall of a major block-bounding normal fault that was active during deposition. It is interpreted as a debris flow triggered by slope collapse.
Friday, 12 September 2008
Image of the week #2
This is from my PhD thesis. Although at first sight it probably looks like a cross-section through a fold/thrust belt, the scale is somewhat different. It's actually a scan of a large thin section. The folds and thrusts are a small-scale slump in finely interbedded sandstone and mudstone of the Albert Formation of New Brunswick, Canada. The base of the slump cuts down through the underlying stratigraphy from left to right. Having measured up a large number of folds in similar slump beds, I found that the palaeoslope was roughly perpenicular to the local faults. So these slumps may have formed during fault-induced slope instability.
Friday, 5 September 2008
Image of the week #1
This is an idea that I've blatantly stolen from the Clastic Detritus blog. Each Friday I'll put up an image: probably mainly field photographs, but also computer-generated images and such like from my digital outcrop mapping research.
This week's image is a nice example of a fault zone from the Suez rift, Egypt (There will probably be a lot of images from Egypt in this series). This is the Nukhul fault, juxtposing Cretaceous chalk of the pre-rift Sudr Formation against the syn-rift Miocene Abu Zenima and Nukhul formations. A sliver of Eocene pre-rift Darat Formation is caught between the paired slip surfaces of the main fault zone, and is internally deformed. In the hanging wall of the main fault zone (to the right), a series of minor faults occur in a damage zone about 50 m wide. The minor faults tip out downward, with one fault showing a duplex pattern near its tip as it merges into bedding.
This week's image is a nice example of a fault zone from the Suez rift, Egypt (There will probably be a lot of images from Egypt in this series). This is the Nukhul fault, juxtposing Cretaceous chalk of the pre-rift Sudr Formation against the syn-rift Miocene Abu Zenima and Nukhul formations. A sliver of Eocene pre-rift Darat Formation is caught between the paired slip surfaces of the main fault zone, and is internally deformed. In the hanging wall of the main fault zone (to the right), a series of minor faults occur in a damage zone about 50 m wide. The minor faults tip out downward, with one fault showing a duplex pattern near its tip as it merges into bedding.
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