10,372
edits
Changes
Jump to navigation
Jump to search
Line 1:
Line 1: − + + + + + + − + Line 14:
Line 19: − + + − + Line 27:
Line 33: − + Line 34:
Line 40: − + + + Line 44:
Line 52: − + − +
How to plot the strike data to the Rosette diagram (view source)
Revision as of 13:03, 14 July 2015
, 13:03, 14 July 2015no edit summary
=Definition=
{{Wiki Write Off Entry
|image=AAPG-WIKI-Write-off.jpg
|student chapter=Universitas Diponegoro
|competition=June 2015
}}
==Definition==
The orientation of a rock bed, fault, fracture, cuestas, igneous dikes, and sills can be described using strike and dip of the rock. Strike is direction of the line formed by the intersection of a fault, bed, or other planar feature and a horizontal plane. Strike indicates the attitude or position of linear structural features such as faults, beds, joints, and folds. Dip is the angle at which a planar feature is inclined to the horizontal plane; it is measured in a vertical plane perpendicular to the strike of the feature.<ref>http://www.britannica.com/science/strike-geology</ref>
The orientation of a rock bed, fault, fracture, cuestas, igneous dikes, and sills can be described using strike and dip of the rock. Strike is direction of the line formed by the intersection of a fault, bed, or other planar feature and a horizontal plane. Strike indicates the attitude or position of linear structural features such as faults, beds, joints, and folds. Dip is the angle at which a planar feature is inclined to the horizontal plane; it is measured in a vertical plane perpendicular to the strike of the feature.<ref>http://www.britannica.com/science/strike-geology</ref>
[[File:Fig1ST.png|framed|center|Figure 1. Strike, dip, and dip direction<ref>http://geology.wikia.com/wiki/Strike_and_dip?file=Strike.gif</ref>]]
[[File:Fig1ST.png|framed|center|Figure 1. Strike, dip, and dip direction<ref>http://geology.wikia.com/wiki/Strike_and_dip?file=Strike.gif</ref>]]
=Brunton Compass=
==Brunton Compass==
Usually the direction of strike and dip can be determined easily with left hand rule. They also can be measured accurately with Brunton Compass. Parts of Brunton Compass explained by Figure 2:
Usually the direction of strike and dip can be determined easily with left hand rule. They also can be measured accurately with Brunton Compass. Parts of Brunton Compass explained by Figure 2:
* Measure vertical angles
* Measure vertical angles
* Measure bearings
* Measure bearings
* Set local declination[3]
* Set local declination
In determine the direction of strike and dip, there are four quadrants at Brunton Compass such as North East, North West, South East, and South West. Each of them have value 0-90 degree. For example in Figure 3, N40o W mean the direction of strike is 40o from North to West. 45o is amount of dip. The direction of dip always perpendicular with direction of strike, so we know the direction of dip is N50o E.
In determine the direction of strike and dip, there are four quadrants at Brunton Compass such as North East, North West, South East, and South West. Each of them have value 0-90 degree. For example in Figure 3, N40o W mean the direction of strike is 40o from North to West. 45o is amount of dip. The direction of dip always perpendicular with direction of strike, so we know the direction of dip is N50o E.
[[File:Direction of strike and dip.png|framed|center|Figure 3. Direction of strike and dip<ref name=geo/>]]
[[File:Direction of strike and dip.png|framed|center|Figure 3. Direction of strike and dip<ref name=geo/>]]
=How to Measure Strike=
==How to Measure Strike==
To measure strike of rock we can used Brunton Compass. The steps are:
To measure strike of rock we can used Brunton Compass. The steps are:
# Place the bottom EDGE of the compass flat against the plane of interest. (The direction of sighting armature follow the direction of strike)
# Place the bottom EDGE of the compass flat against the plane of interest. (The direction of sighting armature follow the direction of strike)
[[File:Measurestrike.png|framed|center|Figure 5. Measure strike with Brunton Compass <ref>http://courses.geo.ucalgary.ca/glgy203/images/sd.htm</ref>]]
[[File:Measurestrike.png|framed|center|Figure 5. Measure strike with Brunton Compass <ref>http://courses.geo.ucalgary.ca/glgy203/images/sd.htm</ref>]]
=Rosette Diagram=
==Rosette Diagram==
The direction of strike indicate the direction of main force of plat tectonic in there regional. It can be determined with rosette diagram.
The direction of strike indicate the direction of main force of plat tectonic in there regional. It can be determined with rosette diagram.
The radial histogram in rosette diagram (the yellow one on Figure 6) show the direction of strike.
The radial histogram in rosette diagram (the yellow one on Figure 6) show the direction of strike.
=Case Study=
==Case Study==
Indonesia is a country located between three major plates, there are Eurasian Plate, Indo-Australia Plate and Pacific Plate. Eurasian Plate have opposite moving direction with Indo-Australia Plate. Eurasian Plate have moving direction about
Indonesia is a country located between three major plates, there are Eurasian Plate, Indo-Australia Plate and Pacific Plate. Eurasian Plate have opposite moving direction with Indo-Australia Plate. Eurasian Plate have moving direction about
Base rock of Java Island is claystone. At Karangrangsambung, Kebumen, Center of Java, there are outcrops of claystone, base rock of Java Island, it is called Karangsambung Formation.
Base rock of Java Island is claystone. At Karangrangsambung, Kebumen, Center of Java, there are outcrops of claystone, base rock of Java Island, it is called Karangsambung Formation.
On June 16, 2015 Geophysics of University of Indonesia held Field Trip to Karangsambung, and observed strike of claystone at Kalimandala Karangsambung. The result of the observation is:
On June 16, 2015 Geophysics of University of Indonesia held Field Trip to Karangsambung, and observed strike of claystone at Kalimandala Karangsambung. The result of the observation is:
[[File:Rosette diagram.png|framed|center|Figure 7. The rosette diagram from the data ]]
[[File:Rosette diagram.png|framed|center|Figure 7. The rosette diagram from the data ]]
Two main force compress the rock between them, so the rock become stress. The main force that come from N7o E is resultant force between Eurasian Plate and Pacific Plate. Then the main force that come from N97o E is resulted by Indo-Australia (see Figure 8). So, the result of strike measurement in Karangsambung agree with fact.
Two main force compress the rock between them, so the rock become stress. The main force that come from N7o E is resultant force between Eurasian Plate and Pacific Plate. Then the main force that come from N97o E is resulted by Indo-Australia (see [[:File:Gaya utama Indonesia.jpg|Figure 8]]). So, the result of strike measurement in Karangsambung agree with fact.
[[File:Gaya utama Indonesia.jpg|framed|center|Figure 8. Plate tectonic around Indonesia]]
[[File:Gaya utama Indonesia.jpg|framed|center|Figure 8. Plate tectonic around Indonesia]]
=Reference=
==Reference==
<references />
<references />