Sunday, February 28, 2010

GRASS VALLEY EXTRUSIONS ABOUT HURRICANE FAULT, Hf, AND IMPROVED DIAGRAM

EARTH SCIENCE postings from www.googleearth.com are reported in blogsites in: www.PorOgle.blogspot.com for other locations.

THIS DIAGRAM PERTAINS TO THE CORIOLIS ROTATIONS NOTICED IN THE FOLLOWING GOOGLE EARTH PHOTO:
Tilt of the CRUST near the Hurricane Fault, Hf
The above model shows that the base of the crust is moved to the east by the relative faster movement of the Mantle. This is anticipated to be faster due to the lesser tidal effect there, because of the further distance from the moon, and also due to the protrusion of the Crust into the atmosphere- where it can incur more friction, both tidal-ly and by drag.
There are other movements of the Crust near Hf, such as:
a. Slicing CCW of the Colorado Plateau, CP, relative to the transition zone;
b. The movement of magma, both rising and later cooling;
c. The normal faulting of the Basin and Range, B&R, relative to the uplifting CP;
d. Rotation of the 30 km Grass Valley Coriolis cell; and,
e. Rebound, due to the loss of mass as erosion of CP transpires.

Taking these in turn, a. has been measured by the striations on slickensides nearby, and it is about 1 mm/year (1 kilometer/million years); b. is a bit more difficult to handle, since the magma rotates CCW when rising and CW when cooling and shrinking. These movements may occur along the same fault planes (and have been found to do so by field geologists), and introduce an uncertainty because of both features occurring in a given canyon wall. Below is a photo taken on the plateau above Hf:


Although the lateral striations indicate side-wise movement, it is not clear whether they move left or right, without finding cat steps or claw indications from chert of other hard rock digging into the opposing rock face. Was the rotation to the left of right?
c. can be solved by normal field measurements by geologists using displacement of a particular layer or bed.
d. Rotation of the Grass Valley is obvious from photos showing circular canyons. Additional information is found by the placement of monoclines due to the compressional force near canyons, and by extensional grabens or sinks on the opposite side of the rotating cell.

e. Rebound can be measured by GPS, as at Fredonia, AZ, but this is a catch-all term, and a net result of all of the other movements combined.
What’s the CONCLUSION regarding the tilting and dipping of sedimentary beds along Hf?
The most general include:
1. The Divide vulcanism, east of the Grass Valley extrusion, represents the high elevation of the dead? local magma chamber. It is high on both sides of Hf, and the AZ roadway can be seen visually as the high point of topography on the low side of Hf. In addition, the basalt from the Divide vulcanism spills out over Hf at this same location.
2. Coriolis cells east of Hf dip-down toward the Virgin River, as does Gooseberry mesa, and we will check whether this dip generally reverses on the southern part of the cell (near the AZ border, where outcrops near the wash dip to SE along a 15 degree dip plane.
THE LATERAL SHEAR MAY BE SEEN IN A NEARBY LOCATION- IN THE SAME WASH:
3. The Mantle drags the base of the crust eastward, but this only shows up at slices near creek junctions and is not indicated for the whole Grass Valley cell. A possibility is that the eastward movement is there, but that it is works on small blocks of crust and is incremental- though prevalent.
THE GROUND SURFACE IS MOVING WESTWARD, RELATIVE TO THE BASE OF THE CRUST, AT THE BELOW LOCATION. THIS CAUSES THE TILT TO THE HURRICANE FAULT EASTWARD WITH DEPTH, AND THE WESTWARD MOVEMENT OF Hf CAN BE SEEN IN THE SPACING OF TERRACES EAST OF THE PRESENT Hf, AT THE HIWAY 9 SWITCHBACKS. THIS IS ABOUT .22 KM/CYCLE, OUT OF A TOTAL OF 5 CYCLES I HAVE DOCUMENTED FOR THE LAST MILLION YEARS. THIS YIELDS ABOUT 200 K.YEARS PER CYCLE, SINCE THE HURRICANE FAULT HAS BEEN ACTUATED. I FURTHER FIND FROM THE KOLOB MESA OF ABOUT 1 M.Y. BASALT, THAT THERE ARE PVM (21 M.Y. INTRUSIVE) ROCKS JUST BELOW THIS BASALT MESA TOP- SHOWING THAT THERE WAS NO Hf AT THAT TIME (SINCE THE ROCKS ROLLED THROUGH STREAM BEDS ACROSS WHAT IS NOW Hf):

THE 5 TERRACES, REPRESENTING 5 SURGES OF Hf, MAY BE SEEN IN THE 5 SLUMPS OF ABOUT EQUAL SPACING ABOVE VIRGIN TOWN, BELOW THE KOLOB MESA; I EXPECT THAT THIS IS SIMULTANEOUS WITH THE MAGNETIC REVERSAL, STRIPING, AND SURGING OF Hf EACH 200 K.YEARS OR SO (THIS IS NOT THE SAME AS THE NORMAL MOVEMENT OF THE HURRICANE FAULT DOWNWARD- WHICH IS LESS THAN A MILLIMETER YEARLY, BELOW Hf):
4. The circular portion of the Virgin River, from Virgin town to the Washington fault, represents an uplift due to magma rise in the past. This is now shrinking and cooling, but the reduction of elevation is now offset by rebound, so that the rotation may be measured but the shrinking cannot. Features such as the Laverkin sink and the Hiway graben exhibit the downdrop, but it is highly local.
PART OF THE LAVERKIN SINK AND THE GRABEN TO THE EAST CAN BE SEEN IN THIS PHOTO TAKEN ALONG HIWAY 9- GOING TO VIRGIN TOWN AND ZION NP (NOTE SLICKENSIDES ON THE LEFT SIDE OF THE ROAD- TO THE EAST; THESE CAN BE USED TO FIND THAT THERE IS NOT ONLY DOWNWARD DISPLACEMENT ALONG THE GRABEN WALL, BUT ALSO MOVEMENT TO THE RIGHT, WHICH IS THE CCW MOVEMENT OF THE COLORADO PLATEAU):

1 comment:

Amy said...

I appreciate your PO very much the picture with the article. Continues to refuel!!