Monday, October 19, 2009
Basin and Range-SE, Fault along I-15 freeway
Above is the area we will investigate this hiking season. This includes the I-15 freeway from New Harmony,UT to Overton Arm of the Lake Mead, NV.
Fall 2009 hiking will be conducted along the SE corner of the B&R tri-state area of AZ, NV, and UT. This will be mainly along the foothills of the Pine Valley Mountains, PVM, to start, and we will gradually work westward along the Virgin River- which is partly incised in the lateral fault zone. The Geology Culture has not seriously considered this shear zone, partly because the Virgin River obscures it, but also because the lateral movement is only on the order of a millimeter/year or so- much slower than the edges of continents- which are moving along the great lateral faults, as in CA.
The first difficulty noted for the continuity of the great B&R fault, is that of Quail Creek- which crosses the shear zone (see photo). This means that the cutting of the anticline is a more forceful action than the slow-moving lateral fault along the freeway I-15. We will try to determine the reasons for this anomaly, since this FACT yields further understanding about the priority of Coriolis rotations.
Although I have just hiked and photographed this feature today, we will return after we have initiated the series of hikes along the PVM foothills to the NE of this anomaly.
Above is a blowup of the previous area shown- of the great lateral fault zone which encircles the B&R. This circumstsnce is hard to swallow, but we will be able to document the southern part of the entity as far as the Valley of Fire, NV, this season. We will attack the anomaly of the Quail Creek crossing the fault zone next, after we have laid the groundwork by hiking the foothills of PVM to the NE of this photo.
This space is left for comments.
Slickensides record the present and previous actions- in this case that the NW limb of the Quail anticline has been shoved to the north, leaving shear marks and silicated slickensides for its CALLING CARD! We will solve this mystery this year, but not now! But below is a taste of the solution:
The SE corner of the B&R is shown below, for a look at the "BIG PICTURE" of the area to be hiked and analyzed:
Pine Valley Mountains, as part of the Virgin drainage, and as the SE corner of the Basin and Range Province
The PVM does indeed have a valley near its apex, and contain a village for escapees from the desert heat. This valley contains the headwaters of the Santa Clara River, and creates a bifurcation of PVM in the Quartz monzonite south from the more basaltic north part. The NW-trending Santa Clara is circularly-shaped, and eventually turns to the south to drain into the Virgin. Oppositely, on the eastern side there is the Wet Muddy creek which drains SE, and connects with the Virgin via Ash Creek- due to springs at the Town of Laverkin (by my reckoning).
The orientation and position of the PVM is anomalous- being oriented NE-SW and located near the SE edge of the down-dropping B&R on the western side of the Hurricane fault (which is at the edge of the Colorado plateau, CP). The PVM is also rare in geological classification- being one of the world’s largest laccoliths (Greek: pond-stone, after the flat top and circular shape of many ponds). It is a geothermally-derived feature, which has risen due to buoyancy as is was heated within the Crust. Due to its siliceous content, and to its weight relative to heavy basalts (2.65 vs. near 3 grams/cm density), it represents a lesser density mass which rose near the surface of the earth, and it remained capped with Mesozoic and Tertiary sedimentary rocks- until it was eroded sufficiently to protrude in our landscape. The surrounding rocks have mostly eroded away since the 21 million year age of its emplacement, and it now remains as a stark prominence as high as 10k feet (above sealevel) over the surrounding Mesozoic landscape.
By my tentative appraisal, PVM has risen because of frictional heat generated by the rotation of B&R brittle rocks clockwise, from the Wasatch and Hurricane faults towards the Overton Arm of Lake Mead, NV. We will be able to easily investigate these remarks, since the Virgin drainage lies at locations where it may be accessed by driving (except for the canyon portion near the AZ-UT border). Confirmation may be found by inspecting concrete slabs along the way, by slickensides’ striations, and by analyzing the dragging of river bends' traces relative to their opposing canyon walls. We will start with the SE side, where PVM is located, because many anomalies occur there, and they will release their secrets- hopefully to fit in with the general portrayal of the circular development of the whole B&R region.
Coriolis-forced rotations must show the following features:
1. Vectors indicating movement of an identifiable feature must be in accordance (or congruent) with other entities which move in the same direction (not the same rotation), but which have different velocities- indicating shear, but insufficiently to create vulcanism and hot springs;
2. Vectors of adjoining Coriolis cells which are rotating in the same direction (CW vs. CW, or CCW vs. CCW for emergng volcanoes) must create heat from friction of brittle rock grating against wall rock- which results in thermal springs or vulcanism;
3. At the edge of a rotating cell, there will occur a recognizable boundary, such as a river trace, and the drag of one side of the valley must be irregular in some sections to obtain the movement of one side relative to the other (not from simple meandering); and,
4. A circular portrayal must contain at least a third of a Arcuate path, for it to be identified- that is, there must be a significant shear path or fracture-fault indication for it to be accepted as a shear feature.
Here is my tentative appraisal of the Leeds-Quail-Laverkin counter-rotating cells (producing anomalous basalt), which fit in the corner of the B&R, Hf, and Virgin River intersection triangle- requiring that one of the cells not be congenial with the others, in order to produce local basalt flows:
We will have to find field evidence for the orientation of the anomalous tucked-in-the-triangle cell- either slickensides, sheared concrete, or dragged local washes! We'll hike there this coming week, and can drive to all three extrusive sites, south of Leeds and west of Laverkin town.
Below is my tentative appraisal, showing vectors- which must agree in direction, except for the ones enlosing volcanic cones- which must disagree (rotate at the common boundary in a conflicting direction- opposite to each other) in order to generate HEAT!
Below are shown photos and Google Earth views of the Leeds volcano- some 5 miles south of the town of Leeds:
This might be called another triple junction, since three almost-linear features come together to either mesh or conflict to produce HEAT OF FRICTION and vulcanism.
Below is the view looking south at the Virgin anticline, which may be noticed to have a divergence of the strike of the beds on this SE limb of the structure:
TO BE CONTINUED, as we hike and get evidence from the field, for our winter's work.