Monday, March 10, 2008
2008 Earth Science Hikes Review
Notwithstanding the "Hot Rocks" shown above (in the April Fool Blog) and in the missive accompanying it, we do have beautiful lakes, with Trout, cool waters, and Red Rocks hereabouts- in RED ROCK COUNTRY.
Below is evidence, from Fissures, that this Hogback, West of Laverkin, is being rotated NOW (downward to the East, clockwise looking north)!
This Photo shows the best evidence that both fracturing and small-scale faulting demonstrate a N-S orientation in brittle Limestone rocks adjacent to Hf.
2008 Report- Hiking near the Hurricane Fault
During Fall and Spring of the 07-08 hiking season, the group concentrated on determining the validity of the following Theory about Movement in the Earth’s Crust:
1. Physical-Mechanical Basis for the conclusions in the following report, abstracted by:
The Earth's decelerated rotation and regularities in orientation of its surface lineaments and faults
Lev A. Maslova, , and Vladimir A. Anokhinb,
aOtero Community College, La Junta, CO, USA
bAll-Russia Research Institute for Geology and Mineral Resources of the World Ocean, St. Petersburg, Russia
Received 2 July 2005; revised 23 August 2005; accepted 26 August 2005. Available online 14 November 2005.
The Earth's crust faults and lineaments group in clusters with predominant N–S and E–W (System I) and NW–SE and NE–SW (System II) directions. The earthquake epicenters of the Benioff seismofocal zones follow the same regularities. In other words, seismofocal zones (epicenters of earthquakes) constitute a part of the regular network of the Earth's crust and lithosphere faults and lineaments. Mathematical modeling of stress distribution in the lithosphere due to a change of the Earth's ellipsoid compression showed that the principal stresses σ1 and σ2 are oriented in N–S and E–W directions, while corresponding shear stresses τ are oriented in NE–SW and NW–SE directions. It is shown that the secular deceleration of the Earth's rotation can be a reasonable mechanism for the change of Earth's ellipsoid compression and, consequently, for the origin of the regular system of faults and lineaments described above.
2. The results may be monitored in the field by determining if the initial conclusions are substantiated for the faults and fractures in the vicinity of Hurricane, Utah- that is, are the diagonal (45 degrees to cardinal directions of N, S, E, and W) fractures and faults due to shear, as contrasted to the N-S orientations being mostly normal faults?
3. A side issue for the local displacements should pertain to the vulcanism found near the Hurricane Fault, Hf. That is, if the fault is an expression of reaction to the shrinkage of the crust as the equatorial bulge decreases, then Hf would not have listric faulting (vertical faulting which becomes horizontal with depth- viewing the fault surface). Rather, along with rising magma, there would be vertical faulting all the way to the Deep Crust (movement would be vertical, similar to that of the magma).
4. Should the Equatorial Bulge Decrease and accompanying faulting and fracturing Theory be pertinent, there should be a division of Mechanically-created movements into 8 segments of the compass rose, of 45 degrees per division:
a. N-S orientations and accompanying E-W orthogonals for normal faulting;
b. NW-SE orientations and accompanying NE-SW orthogonals for shear faulting (including regional lateral, reverse, and compressional faulting).
c. Crustal faulting orientations would be found in 45 degree segments (Octants) of the compass rose, and this would be determined for the age of the Earth at the time of formation. This does not include Geothermally-derived movements. Also, since the earth wobbles and precesses, the ancient faulting and fracturing would appear to be out of synchronization with present orientations. That is, ancient movements (older than Pliocene) would have orientations other than the 8 categories observed now- but would have 8 fossil fracture indications derived from the stress states of those ancient times (older fractures would progressively become more cemented with time- especially for limestones, which have easily dissolved constituents for calcareous cement).
To proceed, Let’s review the Mechanics of the Earth’s Reaction to Length of Day Change- below are listed the important factors:
Mechanics of a Tilted Spinning Elliptical Ball, which has an equatorial Bulge, under the influence of Drag of the atmosphere and the Gravitational attraction of a single large Mass revolving around it (which is spinning at a different rate and gravitationally locked onto the Ball’s Mass).
Ignoring the fact that the Earth-Moon system is subject to the following complications:
1. The spinning Ball is precessing about its axis;
2. The spinning Ball wobbles, or changes the diameter of the precessional axis with time;
3. The Ball is layered in at least 3 different density zones- all shell-like and with increasing temperatures upon approach to the center of the Ball; and,
4. The Ball revolves about a much larger mass which exerts its own gravitational influence on it.
Determine the generalized stress orientations shown on the Ball (directional only) as it slows with time, causing the equatorial bulge to decrease and drop closer to the center of the Ball:
A. What is the immediate orientation of cracks resulting from the shrinkage- north-south or otherwise?; and,
B. Since there is a velocity gradient due to distance from the equator, as the bulge decreases, what is the orientation of shear lines (called Transform faults) as they occur at a greater distance from the equator- E-W?
C. Determine the success in predicting that normal faults on a large scale are oriented along the cardinal directions, and that regional reverse, compressional, and lateral shear faults orient at 45 degrees to the normal faulting.
There is considerable evidence from field observations, near Hf, that fractures orient in the 8 orientations expected. Faulting can be evaluated from Quadrangle and Topographic maps, so that these were not incorporated in the analysis. But Fracturing, which is generally ignored by field geologists, can more easily be seen in outcrops and is found at outcrops of bedrock (but only those found in pairs or of several parallel cracks were considered significant). Hence, conclusions were made only for these or for faulting with small displacement. It should be noted that displacement cannot generally be noticed for lateral faulting anyway, so that what is considered a fracture may instead be faulting with un-measurable displacement. Fractures due to obvious compressional events, such as vulcanism, thrusting, or distortions, were eliminated.
Conclusions:I. Regional normal faults in the SW USA have a significant portion which is oriented N-S, e.g. B&R mountain trends, river pathways- such as Rio Grande, Colorado, and Coal pits, near the edge of the CP, and large-scale fractures near Hf.
II. A minor exception occurred at the slickensides occurring east of Laverkin, on the edge of a N-S oriented graben. There was a decided angle of downdrop of the graben which showed by angles other than vertical that the graben wall had moved right-laterally during the downdrop. That is to say, some of the movement of the graben had a component other than vertical. Partly this aberration was due to the plunge of the graben, but the larger part could not be related to graben rotation- this was definitely sheared on the local level. This lateral component was minor compared to the vertical- some meters during the time the block dropped tens of meters (the Trigonometric tangent of the angle of non-vertical slickensides lineation is about 1/3- this means that the graben is dropping 3x as much as it is sliding to the north).
III. Large-scale fractures occur on a NW-SE orientation, such as the alignment of Wet Sandy and Santa Clara river paths, but these cannot be proved as being regional systems. The correlation of these orientations is demonstrated by the erosion channels developed in response to regional weaknesses in the surface rocks. Other means, such as slickensides and lineations in the outcrops will have to be measured to more positively relate river ways to fractures or faulting. The fact that major springs occur along erosional channels is further documentation that cracks in the surface are kept open by active stressing and straining of the solid rocks.
IV. It was noticed from both fissures and a river pathway that fractures occur in orthogonal patterns. That is, a fracture oriented NW-SE would have a nearby NE-SW companion, generally at right angles to the first expression. Sometimes there are fractures which deviate by 20 degrees or so from this pattern, and these can be related to multiple splays of Hf.
V. The most impressive N-S fractures displayed in the limestone were within the closest kilometer to Hf. The 2nd km east of Hf displayed more randomness of orientation, and had multiple patterns. However, the dominance of N-S orientations was still apparent. Further distant, orientations began to give way to the diagonals (NW or NE), and it is believed that these are not shown in the first kilometer because of re-cementing of the fractures by precipitation of calcareous cement. This could occur whenever uplift of CP- at the edge, by rising magma- shoved the sedimentary column upward at the lip, to be later superceded by relaxation whenever CP came under the influence of extension of the western US.
VI. Altogether, my assessment of large-scale fracturing and faulting as it relates to decrease in rotation rate and increase of day length is positive. There are undoubtedly complications which cause confusion in interpretation, such as thermally-induced movements and vulcanism which is induced by heat from conversion of minerals to a more compact state. How long it takes for the old fracture system to heal and the new one to emerge is an unknown. There is undoubtedly a time constant regulating this transition, on the order of more than a milllion years.
The most likely difficulty in interpretation is that of fossil fractures created in times in which location of the north rotation pole occurs at a greatly different position than now exists This transient period may be difficult to measure, and may be on the scale of a few million years. A place to study this factor is easily seen by noticing the change at the dogleg in the Hawaiian- Emperor Chain at the 41 mybp time. This may be seen on a map of the Pacific Basin floor, where there is a gradual movement of seamounts from the N-S orientation to one of NW-SE display- the ages have been measured for your own calculation of the Time Constant. (any good National Geographic Map will suffice). If the finding that Transforms are related to differential velocities caused by large changes of the north rotation pole of the Earth, then there is a clue that some outside influence (such as a large Impact) has occurred at the 41 mybp age. But other changes are noted at the Earth's Surface at this time- such as the collision (Impact) of the Indian Subcontinent with Asia.
Notice that this E-W Orthogonal fracture cuts across the Virgin Canyon, so that it cannot be explained by spalling into the canyon due to gravitational force.
Photos above and below are different by a scan to the right, so that you can see the quarry pond to the right side of the upper one.
Laverkin Hogback and Monocline is in the distance, the north wall of the Graben is to the right, and I am standing on graben fill to the NE of Laverkin (Pah Tempe Hot Spring is on the bank of Virgin River, and is unseen to the south), and the quarry edge is seen on the first photo, with vulcanism further to the west.
Laverkin Monocline as seen from the south
CONJECTURE: The incipient Hogback (SW of Laverkin), the tilting Graben (E), and the quarry multi-faulting (NE) are all related to the shrinkage of the Magma chamber which has produced the local vulcanism- as it cools deep underground below Hf (via Pah Tempe Hot Springs and fractures). This shrinkage produces a dropping of local crustal blocks- all pointing to the epicenter above the deep Crust containing Hot Rock (after working on this for 2 years, Ben allayed all fears of violating the previous analyses of others by saying just one word about the appraisal of all this- Laramide!)
This View from Laverkin Hogback, looking NE, shows the sedimentry column tilting downward, N toward the Quarry.
This large Fissure, looking S from the E side of Laverkin Hogback, shows how it is tilting faster than erosion can fill it- NOW!
The View to the E shows that everything descends to the North of Laverkin (that is to the west of Hf). Hard to see is the tilt of rocks south of the basaltic mesa (left upper corner of Photo) dipping oppositely- we will document this later while hiking near the 7 Falls in Laverkin Gorge.
The Present Tilting down to the East of the Monocline (which produces a Hogback) has caused a shearing off of the back side of this Householder's Lot
This same linear set of Fissures shows the orientation to the N