Geologic Processes on the Moon/Tectonic Processes - Revision history

Jarogers2001: Tectonic Processes moved to Geologic Processes on the Moon/Tectonic Processes

2008-10-29T10:36:56Z

Tectonic Processes moved to Geologic Processes on the Moon/Tectonic Processes

Jarogers2001: /* Articles in this Series */

2008-08-22T23:19:41Z

Articles in this Series

Jarogers2001: /* Articles in this Series */

2008-08-22T23:18:53Z

Articles in this Series

Jarogers2001: /* Articles in this Series */

2008-08-22T23:16:09Z

Articles in this Series

Jarogers2001: /* Cooling (endogenous) */

2008-08-22T23:13:43Z

Cooling (endogenous)

Jarogers2001 at 05:47, 21 August 2008

2008-08-21T05:47:33Z

Jarogers2001: /* Volcanism as a Tectonic Process (endogenous) */

2008-08-21T05:44:30Z

Volcanism as a Tectonic Process (endogenous)

Jarogers2001: /* Volcanism as a Tectonic Process (endogenous) */

2008-08-21T05:39:41Z

Volcanism as a Tectonic Process (endogenous)

Jarogers2001: /* Volcanism as a Tectonic Process (endogenous) */

2008-08-21T05:31:58Z

Volcanism as a Tectonic Process (endogenous)

Jarogers2001 at 05:27, 21 August 2008

2008-08-21T05:27:52Z

@@ Line 66: / Line 66: @@
 *[[Geologic Processes on the Moon]] - Parent Article
 *[[Cratering on the Moon]] - First Article
-*[[Tectonic Processes]] - Second Article (You Are Here)
+*[[Tectonic Processes]] - Second Article '''(You Are Here)'''
 *[[Volcanism]] - Third Article

@@ Line 66: / Line 66: @@
 *[[Geologic Processes on the Moon]] - Parent Article
 *[[Cratering on the Moon]] - First Article
-*[[Tectonic Processes]] - Second Article
+*[[Tectonic Processes]] - Second Article (You Are Here)
 *[[Volcanism]] - Third Article

@@ Line 65: / Line 65: @@
 ==Articles in this Series==
 *[[Geologic Processes on the Moon]] - Parent Article
-*[[Cratering on the Moon]] - Previous Article
+*[[Cratering on the Moon]] - First Article
-*[[Volcanism]] - Next Article
+*[[Tectonic Processes]] - Second Article

← Older revision		Revision as of 23:13, 22 August 2008
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	[[Image:GP3Fig_13.jpg\|thumb\|left\|Figure 13]]The only currently active endogenous tectonic force is that induced by the moon’s continued secular cooling. With cooling comes shrinkage of the more plastic mantle. However, the rigid crust cannot shrink with it. This creates local stress fields which are eventually released by thrust faulting (the crust on one side of the fault slides up diagonally over the other side). Similar faults exist on Mercury where the shrinkage has been even greater. While these faults are small, there are many of them, and they are continuing to form. Faults from this cause are likely not visible from earth-based telescopes. Figure 13 is an Apollo image of a fault possibly created in this manner.		[[Image:GP3Fig_13.jpg\|thumb\|left\|Figure 13]]The only currently active endogenous tectonic force is that induced by the moon’s continued secular cooling. With cooling comes shrinkage of the more plastic mantle. However, the rigid crust cannot shrink with it. This creates local stress fields which are eventually released by thrust faulting (the crust on one side of the fault slides up diagonally over the other side). Similar faults exist on Mercury where the shrinkage has been even greater. While these faults are small, there are many of them, and they are continuing to form. Faults from this cause are likely not visible from earth-based telescopes. Figure 13 is an Apollo image of a fault possibly created in this manner.
		+
		+	==Articles in this Series==
		+	*[[Geologic Processes on the Moon]] - Parent Article
		+	*[[Cratering on the Moon]] - Previous Article
		+	*[[Volcanism]] - Next Article

@@ Line 2: / Line 2: @@
    |__TOC__
    |}
 {{GPOTM}}
 Tectonism refers to those forces that form and deform the lunar surface. Examples of these forces include the formation of mare ridges and arcuate rilles, along with relatively weak moonquakes. The forces causing deformation can be endogenous (forces generated within the moon’s interior) or external (forces generated by external objects such as a meteorite impact). Below we will examine the nature and history of these various forces, along with the lunar features caused by each.

← Older revision		Revision as of 05:44, 21 August 2008
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−	[[Image:GP3Fig_11.jpg\|thumb\|200px\|Figure 11<BR/>Gassendi.]][[Image:GP3Fig_12.jpg\|thumb\|192px\|left\|Figure 12<BR/>Petavius.]]Floor fractured craters are craters that have a series of rilles in their floors created by volcanic processes (these must be distinguished from sinuous rilles, which also occur in craters). When large meteorites strike the moon, they produce faults deep beneath that crater’s floor. If rising magma accesses these faults, it will preferentially track up these ‘zones of weakness’ in its movement towards the surface. Once under the floor of the crater, the magma collects in a pocket. With sufficient pressure, the magma will cause the crater’s floor to bow upwards, and even to fracture into a series of plates. Thus, floor fracture craters are the end result of lava creating pressure underneath the floor of a crater. Since magma is preferentially found in the lunar basins, most floor fracture craters are found adjacent to the great basins. Examples of floor fractured craters include Crater Gassendi (fig 11) and Crater Petavius (fig 12).	+	[[Image:GP3Fig_11.jpg\|thumb\|200px\|Figure 11<BR/>Gassendi, a floor-fractured crater in which magma rose through shockwave-created faults and pooled beneath the crater floor]][[Image:GP3Fig_12.jpg\|thumb\|192px\|left\|Figure 12<BR/>Petavius, another floor-fractured crater]]Floor fractured craters are craters that have a series of rilles in their floors created by volcanic processes (these must be distinguished from sinuous rilles, which also occur in craters). When large meteorites strike the moon, they produce faults deep beneath that crater’s floor. If rising magma accesses these faults, it will preferentially track up these ‘zones of weakness’ in its movement towards the surface. Once under the floor of the crater, the magma collects in a pocket. With sufficient pressure, the magma will cause the crater’s floor to bow upwards, and even to fracture into a series of plates. Thus, floor fracture craters are the end result of lava creating pressure underneath the floor of a crater. Since magma is preferentially found in the lunar basins, most floor fracture craters are found adjacent to the great basins. Examples of floor fractured craters include Crater Gassendi (fig 11) and Crater Petavius (fig 12).

	==Tidal Interactions (external)==		==Tidal Interactions (external)==

@@ Line 36: / Line 36: @@
-[[Image:GP3Fig_9.jpg|thumb|200px|Figure 9<BR/>]][[Image:GP3Fig_8.jpg|thumb|200px|left|Figure 8<BR/>]][[Image:GP3Fig_10.jpg|thumb|192px|left|Figure 10]]Mare ridges form in a variety of situations, though all are related to the stresses induced by lava flows. One type forms over submerged basin rims. This type begins when magma fills the inner reaches of the basin, eventually covering an inner basin rim. At this point we have a shallow shelf of lava over the rim and a much deeper shelf where the rim falls off (on the sides).  The lava will subside more over the deep area and less over the shallow area, inducing a local stress field in the cooling, plastic lava.  In such an area, a mare ridge will form along the basin’s covered rim.  Indeed, it is only by examining such mare ridges that we can tell where submerged basin rings exist! Excellent examples of mare ridges are visible, in small telescopes, over Mare Imbrium (Fig 6),  Mare Serenitatis (Fig 7),  and the smaller Sinus Aestuum.
+[[Image:GP3Fig_9.jpg|thumb|200px|Figure 9<BR/>Linear mare ridge produced by either a linear fault or a blind thrust fault]][[Image:GP3Fig_8.jpg|thumb|200px|left|Figure 8<BR/>Linear mare ridge produced by either a linear fault or a blind thrust fault]][[Image:GP3Fig_10.jpg|thumb|192px|left|Figure 10<BR>Another indeterminate mare ridge section]]Mare ridges form in a variety of situations, though all are related to the stresses induced by lava flows. One type forms over submerged basin rims. This type begins when magma fills the inner reaches of the basin, eventually covering an inner basin rim. At this point we have a shallow shelf of lava over the rim and a much deeper shelf where the rim falls off (on the sides).  The lava will subside more over the deep area and less over the shallow area, inducing a local stress field in the cooling, plastic lava.  In such an area, a mare ridge will form along the basin’s covered rim.  Indeed, it is only by examining such mare ridges that we can tell where submerged basin rings exist! Excellent examples of mare ridges are visible, in small telescopes, over Mare Imbrium (Fig 6),  Mare Serenitatis (Fig 7),  and the smaller Sinus Aestuum.
@@ Line 44: / Line 44: @@
-[[Image:GP3Fig_11.jpg|thumb|200px|Figure 11<BR/>]][[Image:GP3Fig_12.jpg|thumb|192px|left|Figure 12<BR/>]]Floor fractured craters are craters that have a series of rilles in their floors created by volcanic processes (these must be distinguished from sinuous rilles, which also occur in craters). When large meteorites strike the moon, they produce faults deep beneath that crater’s floor. If rising magma accesses these faults, it will preferentially track up these ‘zones of weakness’ in its movement towards the surface. Once under the floor of the crater, the magma collects in a pocket. With sufficient pressure, the magma will cause the crater’s floor to bow upwards, and even to fracture into a series of plates. Thus, floor fracture craters are the end result of lava creating pressure underneath the floor of a crater. Since magma is preferentially found in the lunar basins, most floor fracture craters are found adjacent to the great basins. Examples of floor fractured craters include Crater Gassendi (fig 11) and Crater Petavius (fig 12).
+[[Image:GP3Fig_11.jpg|thumb|200px|Figure 11<BR/>Gassendi.]][[Image:GP3Fig_12.jpg|thumb|192px|left|Figure 12<BR/>Petavius.]]Floor fractured craters are craters that have a series of rilles in their floors created by volcanic processes (these must be distinguished from sinuous rilles, which also occur in craters). When large meteorites strike the moon, they produce faults deep beneath that crater’s floor. If rising magma accesses these faults, it will preferentially track up these ‘zones of weakness’ in its movement towards the surface. Once under the floor of the crater, the magma collects in a pocket. With sufficient pressure, the magma will cause the crater’s floor to bow upwards, and even to fracture into a series of plates. Thus, floor fracture craters are the end result of lava creating pressure underneath the floor of a crater. Since magma is preferentially found in the lunar basins, most floor fracture craters are found adjacent to the great basins. Examples of floor fractured craters include Crater Gassendi (fig 11) and Crater Petavius (fig 12).
 ==Tidal Interactions (external)==

@@ Line 32: / Line 32: @@
-[[Image:GP3Fig_6.jpg|thumb|200px|left|Figure 6<BR/>Mare ridges in Mare Imbrium, formed over a submerged basin rim]]Other types of tectonic activity are found in association with volcanism.  Lava, because it comes from the mantle, is denser than the overlying crust.  This denser rock, once it pools on the surface, creates local stress fields in the underlying bedrock, activating preexisting faults and creating arcuate rills. These stresses also produce mare ridges and floor fractured craters. We will address each of these in turn.
+[[Image:GP3Fig_6.jpg|thumb|200px|left|Figure 6<BR/>Mare ridges in Mare Imbrium, formed over a submerged basin rim]][[Image:GP3Fig_7.jpg|thumb|300px|Figure 7<BR/>Mare ridges in Mare Serenitatis, formed over a submerged basin rim]]Other types of tectonic activity are found in association with volcanism.  Lava, because it comes from the mantle, is denser than the overlying crust.  This denser rock, once it pools on the surface, creates local stress fields in the underlying bedrock, activating preexisting faults and creating arcuate rills. These stresses also produce mare ridges and floor fractured craters. We will address each of these in turn.
-[[Image:GP3Fig_7.jpg|thumb|300px|Figure 7<BR/>Mare ridges in Mare Serenitatis, formed over a submerged basin rim]][[Image:GP3Fig_8.jpg|thumb|200px|left|Figure 8<BR/>]][[Image:GP3Fig_10.jpg|thumb|Figure 10]][[Image:GP3Fig_9.jpg|thumb|200px|left|Figure 9<BR/>]]Mare ridges form in a variety of situations, though all are related to the stresses induced by lava flows. One type forms over submerged basin rims. This type begins when magma fills the inner reaches of the basin, eventually covering an inner basin rim. At this point we have a shallow shelf of lava over the rim and a much deeper shelf where the rim falls off (on the sides).  The lava will subside more over the deep area and less over the shallow area, inducing a local stress field in the cooling, plastic lava.  In such an area, a mare ridge will form along the basin’s covered rim.  Indeed, it is only by examining such mare ridges that we can tell where submerged basin rings exist! Excellent examples of mare ridges are visible, in small telescopes, over Mare Imbrium (Fig 6),  Mare Serenitatis (Fig 7),  and the smaller Sinus Aestuum.
+[[Image:GP3Fig_9.jpg|thumb|200px|Figure 9<BR/>]][[Image:GP3Fig_8.jpg|thumb|200px|left|Figure 8<BR/>]][[Image:GP3Fig_10.jpg|thumb|192px|left|Figure 10]]Mare ridges form in a variety of situations, though all are related to the stresses induced by lava flows. One type forms over submerged basin rims. This type begins when magma fills the inner reaches of the basin, eventually covering an inner basin rim. At this point we have a shallow shelf of lava over the rim and a much deeper shelf where the rim falls off (on the sides).  The lava will subside more over the deep area and less over the shallow area, inducing a local stress field in the cooling, plastic lava.  In such an area, a mare ridge will form along the basin’s covered rim.  Indeed, it is only by examining such mare ridges that we can tell where submerged basin rings exist! Excellent examples of mare ridges are visible, in small telescopes, over Mare Imbrium (Fig 6),  Mare Serenitatis (Fig 7),  and the smaller Sinus Aestuum.
@@ Line 44: / Line 44: @@
-[[Image:GP3Fig_11.jpg|thumb|200px|left|Figure 11<BR/>]][[Image:GP3Fig_12.jpg|thumb|Figure 12<BR/>]]Floor fractured craters are craters that have a series of rilles in their floors created by volcanic processes (these must be distinguished from sinuous rilles, which also occur in craters). When large meteorites strike the moon, they produce faults deep beneath that crater’s floor. If rising magma accesses these faults, it will preferentially track up these ‘zones of weakness’ in its movement towards the surface. Once under the floor of the crater, the magma collects in a pocket. With sufficient pressure, the magma will cause the crater’s floor to bow upwards, and even to fracture into a series of plates. Thus, floor fracture craters are the end result of lava creating pressure underneath the floor of a crater. Since magma is preferentially found in the lunar basins, most floor fracture craters are found adjacent to the great basins. Examples of floor fractured craters include Crater Gassendi (fig 11) and Crater Petavius (fig 12).
+[[Image:GP3Fig_11.jpg|thumb|200px|Figure 11<BR/>]][[Image:GP3Fig_12.jpg|thumb|192px|left|Figure 12<BR/>]]Floor fractured craters are craters that have a series of rilles in their floors created by volcanic processes (these must be distinguished from sinuous rilles, which also occur in craters). When large meteorites strike the moon, they produce faults deep beneath that crater’s floor. If rising magma accesses these faults, it will preferentially track up these ‘zones of weakness’ in its movement towards the surface. Once under the floor of the crater, the magma collects in a pocket. With sufficient pressure, the magma will cause the crater’s floor to bow upwards, and even to fracture into a series of plates. Thus, floor fracture craters are the end result of lava creating pressure underneath the floor of a crater. Since magma is preferentially found in the lunar basins, most floor fracture craters are found adjacent to the great basins. Examples of floor fractured craters include Crater Gassendi (fig 11) and Crater Petavius (fig 12).
 ==Tidal Interactions (external)==

← Older revision		Revision as of 05:27, 21 August 2008
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	Additionally, semi-stable material can be made unstable by an impact’s shock wave. The most common place to find semistable materials is on the rim of a crater’s wall, where the end products of ejection were ‘lobbed’ onto the rim. When a shock waves passes through such materials, they may slide down the steep side wall, in a small landslide (Fig 5). The vast majority of these events are too small to be resolved by earth-based telescopes.		Additionally, semi-stable material can be made unstable by an impact’s shock wave. The most common place to find semistable materials is on the rim of a crater’s wall, where the end products of ejection were ‘lobbed’ onto the rim. When a shock waves passes through such materials, they may slide down the steep side wall, in a small landslide (Fig 5). The vast majority of these events are too small to be resolved by earth-based telescopes.
		+
		+	<BR/><BR/><BR/><BR/>

	==Volcanism as a Tectonic Process (endogenous)==		==Volcanism as a Tectonic Process (endogenous)==