Which came first, the non- Chicken, or the Platinum Egg?

1dave
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Which came first, the non- Chicken, or the Platinum Egg? Dec 8, 2014 16:54:41 GMT -5 adrian65, bushmanbilly, and 4 more like this

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Post by 1dave on Dec 8, 2014 16:54:41 GMT -5

"Seek not for riches, but for understanding" has been my guiding principle.

I started University in 1955, when only kooks believed in impact craters still existing on the earth and the idea of continental rifting was ridiculous.

Geologists had gone to extreme lengths to explain odd formations until mapping of the ocean floors and Gene Shoemaker's devastating facts forced some of them to accept the possibility of a new reality.

There is still a lot of resistance.

What happened 1.1 billion years ago to break apart Rodinia (Russian for "Motherland").

RodinIABreakup

They are still saying "a hot spot arose for some unknown reason under the great lakes."

Duluth Complex

Anorthosite

From Wikipedia, the free encyclopedia
Not to be confused with Anorthite.

Anorthosite /ænˈɔrθəsaɪt/ is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar (90–100%), and a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.

Anorthosite on Earth can be divided into two types: Proterozoic anorthosite (also known as massif or massif-type anorthosite) and Archean anorthosite. These two types of anorthosite have different modes of occurrence, appear to be restricted to different periods in Earth's history, and are thought to have had different origins.

Fe-Ti Anorthosites
Nearly all the titanium mined in the world today comes either directly from magnetite-ilmenite ore bodies associated with anorthosite complexes or placer deposits derived from the weathering of these complexes.

Distribution
Anorthosite complexes occur in a rather narrow band stretching from the San Gabriel Mountains eastward along the Great Lakes into New England. Concentration of anorthosite complexes is so great in the Adirondacks this deposit type is often termed "Adirondack Fe-Ti deposits". Also occur in a second narrow band across northern Europe.

In a Pangaea reconstruction the complexes all lie in a single belt. More peculiar is the fact that all anorthosite complexes are approximately 1.3 BY. That such massive bodies of anorthosite should be emplaced during a relatively short span of the earth’s history is quite puzzling.

Form
Ore deposits are essentially discordant within the host while varying in both shape and size. Some are tabular while others are lensoidal or dike-like. Vary in size from a few million tons to well over 100 million tons. Largest is the Lac Tio (Allard Lake) deposit 1200 meters wide and long by 100 meters thick. Typical ore grade in excess of 30% TiO2.

Genesis
The "billiard ball model" proposed above is generally accepted by most geologists. Controversy remains about the narrow age constraints for anorthosite complexes. One model suggests that the linear trend of the anorthosite belt is indicative of a rift system. However, rocks in active rifts today are rarely anorthosite so there must be additional complications to the model. The Earth's history prior to 1.5BY appears to be one of very stable cratonic land masses and little plate tectonics as we know it today. In fact, active rifting does not seem to have occurred until about 1 BY ago. Thus, the period from 1.5 to 1 BY may be one of transition.

What completed the circle after 3/4 of the crater was moved away - Isostatic rebound?

What is even more amazing is to see the wealth and diversity in the metals that suddenly appeared at that time! PGE = Platinum Group Elements.

Duluth Ores

Is it possible that a huge precious metal comet broke up and peppered the earth during the late Precambrian?

Last Edit: Dec 30, 2018 10:42:52 GMT -5 by 1dave

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MrP fully equipped rock polisher Member since November 2006 Posts: 1,930	Which came first, the non- Chicken, or the Platinum Egg? Dec 8, 2014 19:03:36 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by MrP on Dec 8, 2014 19:03:36 GMT -5 Keep it coming. You sure do some deep research.....................MrP

Fossilman Cave Dweller Member since January 2009 Posts: 20,722	Which came first, the non- Chicken, or the Platinum Egg? Dec 8, 2014 20:24:08 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Fossilman on Dec 8, 2014 20:24:08 GMT -5 Great reads.....
	God,family and life.....

Deleted Deleted Member Member since January 1970 Posts: 0	Which came first, the non- Chicken, or the Platinum Egg? Dec 8, 2014 21:37:36 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Deleted on Dec 8, 2014 21:37:36 GMT -5 Easy query to answer. Fish were laying eggs for millenia before chickens were extant.

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Which came first, the non- Chicken, or the Platinum Egg? Dec 8, 2014 21:46:27 GMT -5 1dave likes this

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Post by Deleted on Dec 8, 2014 21:46:27 GMT -5

Dec 8, 2014 16:54:41 GMT -5 1dave said:

Is it possible that a huge precious metal comet broke up and peppered the earth during the late Precambrian?

I spent a moment in careful consideration of this very cool question.

My gut feeling is it is highly unlikely that this did not happen and most likely that it did. Let me explain.

Having seen really awesome images of other solar system planetary masses (moon, mercury, mars) and seeing the tremendous number of impacts they have experienced it is without doubt the earth has too. The facts that life arose and our weather (water) makes the most turbulent of local planets makes earth look very different. But impacts we have had. Today evidence of all but the most giganteous are wiped away by weather (water), life and tectonic activity.

Given that our host rock has certainly had many meteor/comet strikes; then on a percentage basis some of those must have held precious metals. This also explains why precious metal deposits seem to be concentrated locally and not spread evenly everywhere.

Last Edit: Dec 8, 2014 23:26:48 GMT -5 by Deleted

chassroc
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Which came first, the non- Chicken, or the Platinum Egg? Dec 9, 2014 7:53:04 GMT -5 1dave likes this

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Post by chassroc on Dec 9, 2014 7:53:04 GMT -5

What a difference a generation makes.

You started University about the time a was born.

"I started University in 1955, when only kooks believed in impact craters still existing on the earth and the idea of continental rifting was ridiculous.

Geologists had gone to extreme lengths to explain odd formations until mapping of the ocean floors and Gene Shoemaker's devastating facts forced some of them to accept the possibility of a new reality.

There is still a lot of resistance."

I have not heard anyone with any credibility argue against Plate Theory and Fault Lines in my entire life. San Andreas is now in the dictionary~!

People have theorized the big impact off Cancun wiping out the dinosaurs for most of my life too.

There are some deniers but with credibility, I dont think so.

It is like the people who deny the Earth is warming

captbob no longer being taken for granite St. Pete FL Member since December 2007 Posts: 8,186	Which came first, the non- Chicken, or the Platinum Egg? Dec 9, 2014 9:32:35 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by captbob on Dec 9, 2014 9:32:35 GMT -5 Dec 9, 2014 7:53:04 GMT -5 chassroc said: It is like the people who deny the Earth is warming
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bushmanbilly Cave Dweller Member since October 2008 Posts: 4,719	Which came first, the non- Chicken, or the Platinum Egg? Dec 9, 2014 11:01:00 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by bushmanbilly on Dec 9, 2014 11:01:00 GMT -5 Dec 9, 2014 7:53:04 GMT -5 chassroc said: It is like the people who deny the Earth is warming

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Which came first, the non- Chicken, or the Platinum Egg? Dec 9, 2014 12:29:47 GMT -5 snowmom likes this

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Post by 1dave on Dec 9, 2014 12:29:47 GMT -5

Let's take a look at the nearby Sudbury Complex in Ontario Canada.

SudburyIrruptive

Until 1970 it was known as the Sudbury Irruptive. See the

imagined red volcanic feed that poured out vast amounts of nickle, gold, silver, platinum . . . Just like what happens in the Hawaiian Islands from that hot spot, right?

Old Geology

Geological map of the Copper Cliff area, produced in the 1950s.

SpaceView

Image taken from Space Shuttle Challenger in 1984/1985

en.wikipedia.org/wiki/Sudbury_Basin
Because considerable erosion has occurred since the Sudbury event, an estimated 6 km (3.7 mi) in the North Range, it is difficult to directly constrain the actual size of the Sudbury crater, whether it being the diameter of the original transient cavity, or the final rim diameter.[5]

The deformation of the Sudbury structure occurred in five main deformation events (by age):

* formation of the Sudbury Igneous Complex (1849 Ma)[2]
* the Penokean orogeny (1890-1830 Ma)
* the Mazatzal orogeny (1700-1600 Ma)[6]
* the Grenville orogeny (1400 - 1000 Ma)
* the Lake Wanapitei impact (37 Ma)
QUESTION: What event deformed it to the north-northwest ?

Disputes over origin
Some 1.8 billions of years of weathering and deformation made it difficult to prove that a meteor was the cause of the Sudbury geological structures. A further difficulty in proving that the Sudbury complex was formed by meteor impact rather than by ordinary igneous processes was that the region was volcanically active at around the same time as the impact, and some weathered volcanic structures can look like meteor collision structures. Since then a layer of breccia has been found associated with the impact event[7] and stressed rock formations have been fully mapped.

Geologists reached consensus by about 1970 that the Sudbury basin was formed by a meteor impact.
Reports published in the late 1960s described geological features that were said to be distinctive of meteor impact, including shatter cones[8] and shock-deformed quartz crystals in the underlying rock.[9] In 2014, analysis of the concentration and distribution of siderophile elements as well as the size of the area where the impact melted the rock indicated that a comet rather than an asteroid most likely caused the crater.[10] [11]

Sudbury Shattercone.

en.wikipedia.org/wiki/Sudbury_Basin
The Sudbury Basin, also known as Sudbury Structure or the Sudbury Nickel Irruptive, is a major geologic structure in Ontario, Canada. It is the second-largest known impact crater or astrobleme on Earth, as well as one of the oldest.[1]

The basin is located on the Canadian Shield in the city of Greater Sudbury, Ontario. The former municipalities of Rayside-Balfour and Valley East lie within the Sudbury Basin, which is referred to locally as "The Valley". The urban core of the former city of Sudbury lies on the southern outskirts of the basin.

The Sudbury Basin is located near a number of other geological structures, including the Temagami Magnetic Anomaly, the Lake Wanapitei impact crater, the western end of the Ottawa-Bonnechere Graben, the Grenville Front Tectonic Zone and the eastern end of the Great Lakes Tectonic Zone, although none of the structures are directly related to each other in the sense of resulting from the same geophysical processes.

Formation
The Sudbury basin formed as a result of an impact into the Nuna supercontinent from a bolide approximately 10–15 km (6.2–9.3 mi) in diameter that occurred 1.849 billion years ago[2] in the Paleoproterozoic era.

Debris from the impact was scattered over an area of 1,600,000 km2 (620,000 sq mi) and traveled over 800 km (500 mi) away — rock fragments ejected by the impact have been found as far as Minnesota.[3]

Models suggest that for such a large impact, debris was most likely scattered globally,[4] but has since been eroded away. Its present size is believed to be a smaller portion of a 250 km (160 mi) round crater that the bolide originally created.

Subsequent geological processes have deformed the crater into the current smaller oval shape. Sudbury Basin is the second-largest crater on Earth, after the 300 km (190 mi) Vredefort crater in South Africa, and larger than the 180 km (110 mi) Chicxulub crater in Yucatán, Mexico.

Structure
The full extent of the Sudbury Basin is 62 km (39 mi) long, 30 km (19 mi) wide and 15 km (9.3 mi) deep, although the modern ground surface is much shallower.

The main units characterizing the Sudbury Structure can be subdivided into three groups: the Sudbury Igneous Complex (SIC), the Whitewater Group, and footwall brecciated country rocks that include offset dikes and the Sublayer. The SIC is believed to be a stratified impact melt sheet composed from the base up of sublayer norite, mafic norite, felsic norite, quartz gabbro, and granophyre.

The Whitewater Group consists of a suevite and sedimentary package composed of the Onaping (fallback breccias), Onwatin, and Chelmsford Formations in stratigraphic succession. Footwall rocks, associated with the impact event, consist of Sudbury Breccia (pseudotachylite), footwall breccia, radial and concentric quartz dioritic breccia dikes (polymict impact melt breccias), and the discontinuous sublayer.

Quite a bit like the Duluth Complex, eh? Nothing like Hawaii.

Last Edit: Dec 10, 2014 9:00:32 GMT -5 by 1dave

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Which came first, the non- Chicken, or the Platinum Egg? Dec 9, 2014 15:29:57 GMT -5 1dave, snowmom, and 1 more like this

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Post by gemfeller on Dec 9, 2014 15:29:57 GMT -5

Very interesting post Dave. I've long speculated that large deposits of metals, especially AU and PT, could have derived from asteroid impacts. While metals can and do precipitate from solution, it's hard to explain huge gold deposits like South Africa's Rand that way. Of course all the various geological processes at tectonic plate boundaries are very poorly understood and I've always considered those violent events another option. For instance what caused the miles-deep, violent eruptions of diatremes in S.A. and elsewhere? Impactors or violent plate tectonic events? Or???

Speaking of bolides I've always wondered what defines them since I've seen two displays I thought were bolides (daylight meteorites) in my lifetime. I just searched for a definition and found there's no general agreement except maybe an apparent magnitude of -14 or greater. The ones I saw were definitely similar in magnitude to the recent Chelyabinsk event. The summer between my freshman and sophomore college years I was working at a construction site in s.e Idaho. I'd just handed off a board to a co-worker and happened to glance over my shoulder. An amazing event played out: a very bright object, trailing smoke, cut an arc across the western sky. Then it silently burst into three pieces with fiery phosphorus/magnesium colors, and they eventually disappeared, trailing smoke, behind a distant range of mountains. While the light show appeared to be quite localized I later read it was seen over most of the western U.S. and Canada. I never learned if any meteors reach the ground.

I saw another while I was crossing a street in Salt Lake City just at dusk. The street lights had just come on. As I looked to the south the thing, which I took to be a Soviet nuclear missile -- it was during the height of the Cold War -- appeared to be headed right at me at a relatively low altitude. It was so bright the street lights turned off. I thought I was a goner and started organizing my Last Thoughts when it broke into several pieces then disappeared. The street lights came back on. It was later found to be a meteorite that burst over central Utah. Remnants were later retrieved by scientists from local universities.

As for the acceptance of plate tectonic (continental drift) theory, it gained bad odor among geologists when it was proposed in 1912 by Alfred Wegener. Poor Wegener couldn't explain how it happened and he became an object of ridicule. Sonar, developed in WWII, eventually revealed the volcanic mid-oceanic ridges that drive seafloor spreading and create subduction zones at plate margins. Wegener was right but he lacked proper evidence.

I took my college geology about the same time you did Dave, and there were great mysteries that nagged at me -- the driving forces behind orogeny for one. Many of those mysteries have been explained by PT and the world makes a lot more sense now. But other mysteries remain, like the ones you're exploring in this thread. Good stuff!

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Which came first, the non- Chicken, or the Platinum Egg? Dec 9, 2014 16:34:39 GMT -5 snowmom likes this

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Post by 1dave on Dec 9, 2014 16:34:39 GMT -5

gemfeller Thanks Rick!
I was just reading a PDF on platinum written in 1999.
It still refers to the major producers - nearly all now acknowledged to be impact sites - as intrusives.

Geologic activities can concentrate minerals and elements, but all the original heavy stuff is at the center of the earth now. The radioactive material is what has kept this planet from freezing for the past four billion years.

Any precious metals pushed up by volcanic action has to have arrived within the past 2 billion years.

When an asteroid or comet impacts earth, it is usually traveling between 11 and 72 km per second.
At those speeds, by the time the object has penetrated to some major percent of its diameter, it and a similar amount of native rock has vaporized.
Harmonic waves play strange tricks where they reinforce and cancel out, leaving whole, melting, or vaporizing in odd patterns.
What goes up must cool and come down.

As we enter various supernova remnants, the flavor of incoming bodies change.
We should be able to find those changes in the rock history.
It would be really interesting to search on the moon where erosion isn't a problem!

Last Edit: Dec 9, 2014 16:35:56 GMT -5 by 1dave

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snowmom still telling self it's just a hobby Curiosity is one of the permanent and certain characteristics of a vigorous intellect. Member since April 2014 Posts: 4,480	Which came first, the non- Chicken, or the Platinum Egg? Dec 12, 2014 16:44:28 GMT -5 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by snowmom on Dec 12, 2014 16:44:28 GMT -5 Thank you 1Dave.

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Which came first, the non- Chicken, or the Platinum Egg? Dec 13, 2014 18:50:14 GMT -5 snowmom likes this

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Post by 1dave on Dec 13, 2014 18:50:14 GMT -5

It looks like a comet rich in titanium, platinum, gold, etc, impacted in that area and initiated the break-up of Rodinia and formed the Grenville mineral belt heavy in titanium as the south-southeastern 3/4ths of the crater moved toward the northeast and was smeared into the landscape from there to Norway.

I'm considering an article on Earth's Precious Metals Era, from 2.7 billion years ago until 1 billion years ago when most of our gold, silver, platinum, etc arrived as a "gift" from space.

Last Edit: Dec 13, 2014 18:55:54 GMT -5 by 1dave

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Which came first, the non- Chicken, or the Platinum Egg? Dec 15, 2014 17:26:39 GMT -5 1dave likes this

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Post by snowmom on Dec 15, 2014 17:26:39 GMT -5

and recent research is leaning toward placing the Sudbury Impact at a much later (younger) date, and that it
was a comet and not a meteor which made the impact. (all those minerals, another chapter for your comet gifts
article...) love what you do 1Dave, keep on doing it!

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Which came first, the non- Chicken, or the Platinum Egg? Dec 16, 2014 10:18:20 GMT -5

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Post by 1dave on Dec 16, 2014 10:18:20 GMT -5

This paper gives insight to 1995 geological thinking.

Abstract

The Beaverhead impact structure in SW Montana and Idaho is an allochthonous (moved from place of formation) fragment
of a large impact structure (~ 100 km diameter) that was transported some distance eastward
during the Cretaceous Sevier orogeny. It is the first tectonic fragment of a large impact structure
identified in the geologic record. The present evidence for impact consists of shatter cones,
pseudotachylites(strange melts), and planar deformation features in quartz. The age of the impact is not well constrained but is estimated to be Neoproterozoic to Cambrian (1000-500 Ma).
The Beaverhead impact event must have created other features that may be preserved
elsewhere in western Montana and Idaho. These include proximal and distal ejecta (which may
be misinterpreted as diamictites and/or tuff horizons) and other fragments of the crater floor
containing shatter cones and pseudotachylite.

A large circular gravity, magnetic and topographic anomaly, which could be the root of the impact structure, has been identified near Challis, Idaho.

Beaverhead

An enigmatic lithic tuff, identified in drill cores from the Challis area and an intraformational
quartzite breccia in the Leaton Gulch area may be impact~related deposits, but no definitive
evidence of shock metamorphism has been observed in these materials.
The discovery of more pieces of the Beaverhead puzzle, as well as the recognition of
other large impacts in the geologic record, are likely once the regional geologic community
grows to accept the incidence of such events and becomes more familiar with the features of
shock metamorphism in the field. To that end, the community of geologists in this area should
integrate the Beaverhead structure into their research and teaching curriculum.

Submitted in revised form on March 15, 1994 to:
Proceedings of the Belt Symposium III
Richard Berg, Editor
To be published in Summer, 1995 by the Montana Bureau of Mines and Geology

Meteorite impact cratering is a fundamental geological process on solid-bodied planets
(Shoemaker, 1977). While evidence of this is widely recognized on the other terrestrial planets
in the solar system, the role of cratering in the geological evolution of the Earth is not widely
appreciated. This is due, at least in part, to the fact that meteorite impacts, at this stage in Earth
history, are rare events and, once formed, an impact crater can be obscured and eventually
destroyed by the active tectonic and erosional processes that resurface the Earth. While roughly
20% of the 134+ impact structures identified worldwide are buried, and the rest are eroded to
some level (Grieve, 1991), nearly all still retain some circular geometry. This not only reflects
the bias in recognition toward young, fresh craters, but also reflects the fact that the identification
of many of these features has relied on the remote sensing of circular topographic, gravity or
magnetic anomalies (Dence and others, 1968).

However, large impacts (roughly 100 km in diameter and larger), while rare, may leave
evidence that persists in the geologic record long after the destruction of the circular crater.
Large impacts excavate deep into the crust and result in the uplift of lower crustal and mantle
material (Grieve and others., 1981). Large impacts also produce a large volume of shock-
deformed rocks and minerals, as well as crater ejecta material that may be transported great
distances from the point of impact and preserved in sedimentary basins.

The Beaverhead impact structure in southwest Montana and Idaho is the first example of
a tectonic fragment of a large impact structure preserved in an orogenic belt. As such, it provides
important information about the preservation and identification of impact features in the geologic
record which may lead to future discoveries. From the standpoint of regional geology, the.
Beaverhead impact structure may well provide a unique temporal and structural reference for the
geological history of the western U.S. It is likely that more evidence of large impacts will be
discovered once the regional geologic community is more attuned to the features of shock
metamorphism in the field.

Is there a connection with this and Montana agate? If any of you are interested in collecting shatter cones in the area, this paper tells you where to look for them!

Last Edit: Dec 16, 2014 11:56:07 GMT -5 by 1dave

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Which came first, the non- Chicken, or the Platinum Egg? Dec 29, 2018 11:52:03 GMT -5 grumpybill likes this

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Post by 1dave on Dec 29, 2018 11:52:03 GMT -5

www.usgs.gov/faqs/how-can-i-tell-if-i-have-found-impact-crater-0?qt-news_science_products=0#qt-news_science_products

How can I tell if I have found an impact crater?

There are many natural processes other than impacts that can create circular features and depressions on the surface of the Earth. These include glaciation, volcanism, atolls, uplift, intrusions, and hydrothermal explosions (to name just a few). People also sometimes mistake prehistoric mines and quarries for impact craters.

Although the USGS has been involved in impact crater research, we are neither the experts nor the ultimate authority on impact craters. Canada’s University of New Brunswick Planetary and Space Science Center is the best resource for confirming a structure as an impact crater. They maintain an Earth Impact Database and provide guidelines for identification of impact craters. You can also report a potential impact crater.

I am creating a list of "identifiers."

Present accepted evidence for impact consists of: circular gravity, magnetic and topographic anomalies; simple and complex craters; shatter cones, pseudotachylites (strange melts), and planar deformation features in quartz.

Last Edit: Dec 30, 2018 6:34:36 GMT -5 by 1dave

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Which came first, the non- Chicken, or the Platinum Egg? Dec 30, 2018 6:38:43 GMT -5

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Post by 1dave on Dec 30, 2018 6:38:43 GMT -5

www.passc.net/EarthImpactDatabase/Criteria.html

Criteria for the identification of an impact structure

The principal criteria for determining if a geological feature is an impact structure formed by the hypervelocity impact of a meteorite or comet are listed below. The criteria can be divided into

megascopic (overview – bird’s eye / satellite scale),

macroscopic (can be seen easily seen with the naked eye) and

microscopic (requires a microscope to see) features, as follows:

1. Presence of shatter cones that are in situ (macroscopic evidence).

2. Presence of multiple planar deformation features (PDFs) in minerals within in situ lithologies (microscopic evidence).

3. Presence of high pressure mineral polymorphs within in situ lithologies (microscopic evidence and requiring proof via X-ray diffraction, etc.).

4. Morphometry. On other planetary bodies, such as the Moon and Mars, we rely on the shape of the impact structure to determine its presence and type (simple versus complex, etc.). This is a megascopic quality (i.e., too big to be seen unaided by the human eye, thus requiring remote sensing, aerial photography, detailed mapping of multiple outcrops to assemble and view the typically km- or multiple km-size structure).

On Earth, recognizing impact structures solely by their morphometry is complicated by two factors:

(a) weathering, erosion, burial processes and tectonic deformation can obscure and/or destroy the original shape;
(b) certain terrestrial features generated by means other than impact can have comparable circular form (e.g., volcanoes, salt diapirs, glacigenic features), such that a circular structure alone is not sufficient to claim impact structure status. Some buried craters have been revealed solely by geophysical techniques, although drill core is typically required to reveal macro- and microscopic evidence to prove an impact origin.

5. Presence of an impact melt sheet and/or dikes, and impact melt breccias that were generated due to hypervelocity impact (macroscopic). These bodies typically have a crustal composition derived by the fusion of target rocks (i.e., there is no mantle contribution to the melt). Such melts may be contaminated by meteoritic (projectile) components (the latter requires specialized geochemical analysis to detect the projectile components). Melt sheets may be overlain by so-called fallback breccias (referred to as "suevite" by some workers), and material blasted out of the crater may form ejecta blankets about the original central cavity. For large impact events, ejecta can be distributed globally. Impact melt sheets are recognized by careful mapping and rock sampling followed by microscopy and geochemical analysis.

6. Pseudotachylyte and Breccias: Pseudotachylyte is a rock type generated by faulting at either microscopic or macroscopic scales. However, pseudotachylytes are also associated with seismic faulting due to endogenic processes (e.g., earthquakes due to isostatic rebound and plate tectonics), so they are not exclusively impact generated. However, in association with features listed above, they can be a contributory criterion. Pseudotachylyte associated with impact structures may form in radial and concentric fault systems that help to define the megascopic structure of the crater. Pseudotachylytes can be included in a family of rocks referred to as breccias. Many different types of breccia can be developed as part of the impact process (including impact melt breccias listed in (5) above), but breccias can also form by endogenic processes. The interpretation of breccias therefore requires considerable care and experience. Moreover, they should not be considered diagnostic of impact, but rather contributory evidence.

In terms of relative importance, it is generally considered that criteria 1-3 above are definitive (they all relate to the passage of a shock wave through rock and resulting modification processes), with contributory evidence being added by 4-6 (which result from secondary effects, such as gravitationally driven crater modification). For buried structures that cannot be directly accessed, but are well-preserved as revealed by detailed geophysical techniques (especially seismic data), some workers consider this as strong evidence in favour of an impact origin. Normally, buried craters are verified by drilling and sampling the material directly for evaluation using criteria 1-3 above.

If you have reviewed the above criteria and would still like to report a crater to the Data Manager, please fill out the following form: Report a Crater.

Not mentioned are the shock waves beyond the outer rings that created frozen waves in the rock layers for hundreds of miles around, those wave layers around Upheaval Dome allowed the later weathering to create Utah's famous arches!

Also, the shock waves drove huge amounts of water out of the surrounding thousands of feet of sandstone, leaving the dissolved iron behind to become the liesegang lines in picture rock.

A hundred miles away the water was forced out in such huge quantities that the seams were filled with goethite, and where the surface was nearby, the exiting water created goethite pipes to mark their exit.

Where the water was not allowed to escape, harmonic vibrations turned on and off quartz grain piezoelectric properties, attracting and rejecting nearby iron molecules, and within minutes the curious nodules known as "Moqui Marbles" were formed as far away as Lake Powell.

Last Edit: Dec 30, 2018 7:14:20 GMT -5 by 1dave

I'm a ROCKOLOGIST !

My Published Books: 1936dave.freeforums.net/

1dave misunderstood rock expert Awed by the Universe! Member since October 2013 Posts: 11,937	Which came first, the non- Chicken, or the Platinum Egg? Dec 30, 2018 10:46:50 GMT -5 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by 1dave on Dec 30, 2018 10:46:50 GMT -5
	I'm a ROCKOLOGIST ! My Published Books: 1936dave.freeforums.net/

1dave misunderstood rock expert Awed by the Universe! Member since October 2013 Posts: 11,937	Which came first, the non- Chicken, or the Platinum Egg? Dec 30, 2018 11:25:02 GMT -5 grumpybill likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by 1dave on Dec 30, 2018 11:25:02 GMT -5 I'm in a whimsical mood this morning.
	I'm a ROCKOLOGIST ! My Published Books: 1936dave.freeforums.net/