Upheaval Dome
38.436944444444 - 109.92916666667Koordinaten: 38 ° 26 ' 13 " N, 109 ° 55' 45 " W
The Upheaval Dome (Eng. " uplift peak" ) is a crater-like geological structure in Canyonlands National Park near Moab in the U.S. state of Utah.
The central crater depression measures approximately 1.4 km in diameter, it is over 400 meters deep. The maximum age of the crater is estimated to be 170 million years ( Jurassic). On the surface, it can be seen clearly by its light brown and black colored concentric rings.
Stratigraphic sequence
The oldest pending in the center of Upheaval Dome rock unit is the White Rim Sandstone Member of the Permian Cutler formation. This unit is usually covered in the National Park from a sedimentary load of more than 1600 meters. It follows with an unconformity the Triassic Moenkopi Formation, which in turn is overlaid unconformably by the Chinle formation. The framing is constructed from the steep wall-forming Wingate Sandstone, the Kayenta Formation and the diagonally layered Navajo sandstone.
Structural design
Structurally the Upheaval Dome is a very unusual phenomenon. Moreover, Canyonlands National Park, the rock layers are mostly horizontal or fall only slightly. At Upheaval Dome, however, they form a dome-like state bulging (English " Central Uplift " ), in the center, some layers are often almost perpendicular. Incidence angles were measured from 70 degrees even in the U-shaped plateau ring in the Kayenta Formation still. An annular syncline of 3.5 kilometers in diameter girded the center. It can be observed mainly in the Navajo Sandstone. A little further north could also be mapped with approximately 5 km in diameter, a running concentrically Monoclinic.
A striking feature of the structure is its deviation from a circular shape, rather it is slightly stretched northwards to north- north-east direction. The structures in the central mountain ( fold axes / radial anticline, faults / thrusts ) also deviate from an expected ideal radial symmetry, but they show bilateral symmetry in SE -NW direction. It also outweigh flat against Northwest incident thrust faults (mainly in the central mountain, but can also be observed on the crater rim ). This indicates a general material handling to Southeast - possibly by a meteorite from northwest to explain direction.
Attempts to explain
For the explanation of the bulge, there are two common, commonly known theories:
- Salt dome. Due to the applied load of the hanging wall originating from the Paradox Formation salt was plastically deformed and pushed his as diapir its way to the surface. At Upheaval Dome is believed that the former diapir has been completely removed along with its coverage and the current surface is only the broken stem of the diapir. If true this, then the Upheaval Dome would be the most deeply eroded salt structure of the Earth.
- Eroded meteorite crater. Similar to the Barringer Crater in Winslow, Arizona to the impact of a meteorite is held responsible for the structure, the Upheaval Dome, however, a much deeper story to be present.
There also exists the theory of a kryptovulkanischen explosion.
In the nineties examined geologists and seismologists from NASA and the University of Nevada in Reno the Upheaval Dome in great detail, he has been mapped it and refraktionsseismisch measured. The results of this study spoke of the meteorite theory. A seismic reflection study of 1999 was indeed the salt layer of the Paradox Formation confirm at a depth of 1160 meters underground, but it lies flat and shows only slight relief. Center Windwärts oriented listric faults can also close on a shock wave from above. In 2008, the discovery of quartz shock was announced, an indication of the impact of a meteorite. This discovery has been limited only to a single location with only a few shocked grains. Further evidence suggesting a meteorite impact, are cone of rays, synsedimentary deformation structures such as kompaktionelle deformation bands, power injections, close-knit fault networks in the centimeter range, internal brecciation, cataclastic flow, and rock liquefaction.
Even now, almost everything points to a meteorite impact, the debate about the origin of Upheaval Dome should nevertheless not be completely finished.
Photo Gallery
Syncline in the Navajo Sandstone, north-west side.
Steep raised layers in the crater center