Thursday, February 4, 2010
Hurricane Fault Arcuate feature at AZ border similar to Aleutian Spiral
This is subject to pulses approximately each 200 k.years, as is seen in the above photo, and at the Kolob Mesa just north of Virgin Town.
Adjacent to dynamic features is a cell I have named a REACTIONARY CELL, RC. This is shown below for the zone north of the western Aleutians, which is a CW-ROTATING cell, with a diameter of 300 km.
The direction can be determined by use of GPS data, knowing that the entire Aleutian chain is moving toward the SW, and that the crust is being dragged along with the general rotation (on the north side). A similar small-scale feature is shown below in a digital photo, of Hf near the AZ border, with the diameter on the order of 1 km:
SPIRAL GEOMETRY CALCULATIONS
The case of the Hurricane Fault at the AZ border is valuable for determining the rate of movement and cell boundaries. This is the third (or possibly fourth) of concentric spirals about the Grass Valley vulcanism- which triggered the rotations about Hf, and which left an arcuate path for the Virgin River.
First let’s review the evidence, to determine which rotating cells are pertinent to the study of this DISCOVERY CASE. There are several concentric circles, or circular traces, fitting within the feature extending from the WA fault in Washington City to Virgin Town. This will not include the Fort Pierce Wash trace which has vulcanism on its southern border in AZ- which proceeds to the intersection with the Virgin River at Santa Clara (which has a triple junction with the SC River on the north side of the Virgin).
These Coriolis cells, rotating about Hf, proceed Clockwise, CW, as determined by the direction of lateral thrusting and cat steps in slickensides. This is for cooling cells which shrink and sink with a CW motion- the opposite of magma rising, which rotates CCW for uplifting features. This was solved for the geometry noticed in the Laverkin Sink and graben- where occur slickensides at an angle indicating that the Colorado Plateau, CP, is moving CCW (while presenting rising). The rate of moving there as evidenced by the trigonometry of the slickensides resulted in the lateral movement being about 1/3rd of the vertical movement- yielding about 1.5 mm/year lateral movement for 5 mm/year vertical faulting. Overall, this displacement has been calculated to be about .2 mm/year, but there is an occasional surge of displacement (indicated by terraces) of faster movement.
NOTICE IN THE ABOVE PHOTO, THAT GYPSUM, FROM THE MESOZOIC, HAS BEEN TRANSPORTED UPHILL INTO THE PALEOZOIC rubble about a kilometer. THIS ALLOWS THE RATE OF MOVEMENT TO BE CALCULATED (ABOUT 1 MM/YEAR)
The circumference of this local spiral is about 4 km, as indicated by Google Earth’s horizontal measurements, This calculates that the diameter is about 1.3 km, and for a Grass Valley age of about 1 m.y. There is a rotational velocity of 1 mm/year movement along the E-W canyon wall. This is predicated upon the observed strand OF FRACTURES along the minor canyon of about 1 km. This circular reactionary movement has now reached uphill about a similar distance- forming a slight canyon (with a noticeable spur or splay) which becomes less obvious up the hill above Hf.\
This is all presented in a DIAGRAM- SHOWING THE IMPORTANT MOVEMENTS. NOTICE THAT THE MANTLE MAY BE ROTATING THE BASE OF THE CRUST TO THE EAST (yielding the tilt of the surface beds): Below is another view of the encircling fracture system, actuated by the moving and cooling GRASS VALLEY VULCANISM;
THE CLOSEST CANYON TO THE TOWN OF HURRICANE AND ITS THREE VOLCANIC CRATERS IS LOCATED JUST EAST OF THE HURRICANE AIRPORT. THIS CANYON DOESN'T ALLOW ACCESS TO CP, AS IT IS TOO STEEP TO CLIMB. IT DOES SHOW SIGNIFICANT FRACTURES AND FAULTING, AND WILL BE ANALYZED BELOW: