collapse


* User Info

 
 
Welcome, Guest. Please login or register.
Did you miss your activation email?

* Who's Online

mulletator

Dot Guests: 220 | Dot Users
Dot Hidden: 1

* Board Stats

  • stats Total Members: 13069
  • stats Total Posts: 131937
  • stats Total Topics: 18429
  • stats Total Categories: 5
  • stats Total Boards: 48
  • stats Most Online: 814

* Advertisers

Mining Claims
Gear Pan
The lil Gold Spinner
BC GOLD
The lil Gold Spinner
The Pocket Sluice

Author Topic: Fault Finding  (Read 26499 times)

0 Members and 1 Guest are viewing this topic.

Offline EMF

  • Hero Member
  • ******
  • Posts: 723
  • Kudos: 33
Fault Finding
« on: April 15, 2015, 09:49:57 AM »
When I'm out prospecting I make waypoints on my GPS of any features of interest such as outcrops of certain kinds of rock, old pocket mines, prospect holes, contacts, springs, dikes, veins, float occurrences, or anything else of geological interest. Sometimes there are areas of enrichment where faults intersect veins or dikes, but faults are often obscured by erosion or by their tendency to "smear" into shear zones, making them tricky to find.

In an aerial view, they will show up as line shaped formations that cut through hills or make hills along their path. One of the features that faults create are springs, caused when faults bring impermeable rock into contact with water saturated rock, blocking underground flow and causing the water to flow to the surface.

Using Google Earth Pro, I plotted out my collected waypoints while mapping my area of prospecting. The springs I found aligned themselves right along with one of those line formations that can be seen with Google Earth, revealing a fault zone. The springs are marked as red dots, while the yellow lines enclose the fault/shear zone.

There are many faults, veins and dikes in that area running parallel with the springs fault, creating by the uplift of a nearby granitic pluton. There is a another series of much older fractures that intersect with these formations, and those intersections are some of the places I'm checking out for mineralization.   [ Invalid Attachment ]

[Old attachment removed automatically]

[Old attachment removed automatically]

Offline spudnick

  • Jr. Member
  • ***
  • Posts: 16
  • Kudos: 0
Re: Fault Finding
« Reply #1 on: April 15, 2015, 02:42:55 PM »
Mapping, plotting, good to know  and makes alot of sense  ..i just have to learn GPS.. lol ..  Thanks for sharing and posting EMF.

Offline sunshine

  • PPT Invited
  • *****
  • Posts: 2260
  • Province/State: Ontario, but also prospect in BC
  • Country: ca
  • Kudos: 40
Re: Fault Finding
« Reply #2 on: April 15, 2015, 07:47:14 PM »
Other thing I have noticed is some streams follow the main fault.
See my YouTube channel for fun amateur video:
https://www.youtube.com/channel/UCnz8kX6AZOeZbRt0F9XqVJA

Offline aumbre

  • PPT Invited
  • *****
  • Posts: 500
  • Kudos: 9
Re: Fault Finding
« Reply #3 on: April 16, 2015, 11:10:10 AM »
Recognize alinements from aerial photos.









Offline EMF

  • Hero Member
  • ******
  • Posts: 723
  • Kudos: 33
Re: Fault Finding
« Reply #4 on: April 16, 2015, 01:02:02 PM »
That fact you pointed out, aumbre, is illustrated in the google image by the drainage systems which angle in from the top right. The stream channels that angle in from the top right follow the older fault system that predated the rise of the pluton that created the fault system that runs parallel with the fault indicated by the springs.

The sheared rock of the older system eroded as the land was pushed up with the rise of the pluton, several miles from the top part of the image. The older fractures contain listwanite alteration zones, stream channels, and a few dikes, while the newer set of faults made spaces for the many dikes and veins that formed as the pluton pushed its way upward. Closer to the pluton, the whole area was so intensively fractured that it eroded away to leave a valley between the uplifted area in the image and the mountain itself.

I used the same technique of plotting waypoints from the GPS, but without Google Earth Pro, to connect a series of quartz outcrops and and old pocket diggings to discover that they were all on the same vein. The waypoints were so far from each other, with intervening hills, that much like the springs, I could not see that they were linked until I mapped them. This technique only works easily with steeeply dipping formations, though.

A vein with a more lateral dip would outcrop on a hilly surface all curvy like a logging road and be harder to trace.

Offline UvicProspector

  • Jr. Member
  • ***
  • Posts: 28
  • Kudos: 1
Re: Fault Finding
« Reply #5 on: May 10, 2015, 10:07:16 PM »
Looks like you know your stuff! One additional thing to consider is conjugate fractures planes. If a fault forms, another will make a 60 degree angle in the orientation of the principal stress field. Check the Dip angle of the fault plane to be sure, they will have very similar strike and dip if they are not conjugates faults. If they are conjugates then they will have a strike 180 degrees different or the dip angles difference will be about 60 degrees.

Cheers!


Offline aumbre

  • PPT Invited
  • *****
  • Posts: 500
  • Kudos: 9
Re: Fault Finding
« Reply #6 on: May 11, 2015, 08:02:16 AM »
Dear Uvic,
Did you mix up the words "strike and dip" in the last sentence?

Offline NS Gold Seeker

  • PPT Invited
  • *****
  • Posts: 280
  • Province/State: Nova Scotia
  • Country: ca
  • Kudos: 8
  • Gold is good.
Re: Fault Finding
« Reply #7 on: May 12, 2015, 06:23:57 AM »
In glaciated terrain, streams and brooks can follow faults and be of great significance.  Lakes sometimes line up.
In dessert terrain it is more easy to do interpretation of satelite imagery and aerial photography. Less vegetative cover.
The use of handheld GPS and plotting in the field is amazing and can be a great tool. 
Access to Google Maps, Earth and EarthPro is something that opens up previously unexplored areas.

Fault intersections are great indicators of depositis and the path of fluid movement, crucial to deposit formation.
Suggest looking at shear zones (areas of heavily cleaved outcrops - measure this cleavage direction/dip and try to get a direction of movement of the fault by looking at the dragging of strata or formations in one direction.  Note any indications of iron staining, maybe plot as a different colour point.
Gold is good.

Offline aumbre

  • PPT Invited
  • *****
  • Posts: 500
  • Kudos: 9
Re: Fault Finding
« Reply #8 on: May 12, 2015, 12:59:40 PM »
Theory of "fault order" Motherlode area California.

Ore deposit are found mostly within third order faults.



Possible intersections...

Offline XT18000

  • PPT Invited
  • *****
  • Posts: 321
  • Kudos: 24
  • Better prospecting through chemistry
Re: Fault Finding
« Reply #9 on: May 14, 2015, 05:38:56 AM »
 
  Good work there; now finish it by taking soil samples and rock samples, send to ALS minerals for a 32 element test to see what really there

  not what you hope or think is there. To short of time now to go into that now but if you want or need more information on the subject PM me

  and I'll help you out. There are things that must be done and not be done if the samples are to be of meaningful value.