Bedrock Geology UK North: Carboniferous - Revision history

Dbk: /* Midland Valley of Scotland */

2015-01-30T12:31:31Z

Midland Valley of Scotland

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	<center>		<center>
	<gallery widths=~~300px~~ heights=200px>		<gallery widths=280px heights=200px>
	Image:P064459.jpg\|The lavas of the Clyde Plateau Volcanic Formation (Strathclyde Group) form prominent 'trap features' on the scarp face of the Gargunnock Hills, near Stirling. P064459.		Image:P064459.jpg\|The lavas of the Clyde Plateau Volcanic Formation (Strathclyde Group) form prominent 'trap features' on the scarp face of the Gargunnock Hills, near Stirling. P064459.
	Image:P001097.jpg\|Tuffs from the lower part of the Garleton Hills Volcanic Formation (Strathclyde Group) at Seacliff Harbour, near North Berwick, East Lothian, with the associated volcanic plug of the Bass Rock in the background. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=2395&index=0&total=1&view=viewSearchItem P001097.]		Image:P001097.jpg\|Tuffs from the lower part of the Garleton Hills Volcanic Formation (Strathclyde Group) at Seacliff Harbour, near North Berwick, East Lothian, with the associated volcanic plug of the Bass Rock in the background. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=2395&index=0&total=1&view=viewSearchItem P001097.]

Dbk: /* Midland Valley of Scotland */

2015-01-30T12:31:13Z

Midland Valley of Scotland

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	'''Widespread, intermittent volcanism''' continued from the late Visean into the early Namurian, producing mostly mafic lava but with some volcaniclastic components. One major volcanic sequence that built up in the central and eastern parts of the Midland Valley, the Bathgate Group, may be as much as 1000 m thick and formed a partial barrier between sedimentary systems that persisted until well into Namurian times.		'''Widespread, intermittent volcanism''' continued from the late Visean into the early Namurian, producing mostly mafic lava but with some volcaniclastic components. One major volcanic sequence that built up in the central and eastern parts of the Midland Valley, the Bathgate Group, may be as much as 1000 m thick and formed a partial barrier between sedimentary systems that persisted until well into Namurian times.

	<gallery widths=200px>		<center>
			<gallery widths=300px heights=200px>
	Image:P064459.jpg\|The lavas of the Clyde Plateau Volcanic Formation (Strathclyde Group) form prominent 'trap features' on the scarp face of the Gargunnock Hills, near Stirling. P064459.		Image:P064459.jpg\|The lavas of the Clyde Plateau Volcanic Formation (Strathclyde Group) form prominent 'trap features' on the scarp face of the Gargunnock Hills, near Stirling. P064459.
	Image:P001097.jpg\|Tuffs from the lower part of the Garleton Hills Volcanic Formation (Strathclyde Group) at Seacliff Harbour, near North Berwick, East Lothian, with the associated volcanic plug of the Bass Rock in the background. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=2395&index=0&total=1&view=viewSearchItem P001097.]		Image:P001097.jpg\|Tuffs from the lower part of the Garleton Hills Volcanic Formation (Strathclyde Group) at Seacliff Harbour, near North Berwick, East Lothian, with the associated volcanic plug of the Bass Rock in the background. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=2395&index=0&total=1&view=viewSearchItem P001097.]
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	Image:P005990.jpg\|Clackmannan Group cyclothems revealed in the face of the Blindwells opencast coal workings at Tranent, East Lothian. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=5239&index=0&total=1&view=viewSearchItem P005990.]		Image:P005990.jpg\|Clackmannan Group cyclothems revealed in the face of the Blindwells opencast coal workings at Tranent, East Lothian. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=5239&index=0&total=1&view=viewSearchItem P005990.]
	</gallery>		</gallery>
			</center>

	'''In the west of the Midland Valley''', west of the Bathgate Group barrier, the Clyde Plateau Volcanic Formation is succeeded diachronously by about 30 m of reworked, volcaniclastic strata, followed by about 250 m of largely fluviatile rocks, deposited in channel, floodplain and lacustrine environments. Sporadic, thin coal seams are developed in the latter sequence, whilst a few laterally persistent, marine limestone beds testify to intermittent marine incursions. In the east of the Midland Valley, the volcanic rocks are overlain by up to 800 m of interbedded sandstone and mudstone, with subordinate coal and limestone; the depositional environments were variously fluvial, deltaic and lacustrine. A more extensive lacustrine environment is then represented towards the top of the Strathclyde Group by a sequence of interbedded sandstone and mudstone that exceeds 1000 m in thickness and contains thin seams of oil shale that formed when the lakes were rich in algae. Subordinate lithologies present include coal, limestone (both marine and nonmarine varieties) and pale green, calcareous mudstone.		'''In the west of the Midland Valley''', west of the Bathgate Group barrier, the Clyde Plateau Volcanic Formation is succeeded diachronously by about 30 m of reworked, volcaniclastic strata, followed by about 250 m of largely fluviatile rocks, deposited in channel, floodplain and lacustrine environments. Sporadic, thin coal seams are developed in the latter sequence, whilst a few laterally persistent, marine limestone beds testify to intermittent marine incursions. In the east of the Midland Valley, the volcanic rocks are overlain by up to 800 m of interbedded sandstone and mudstone, with subordinate coal and limestone; the depositional environments were variously fluvial, deltaic and lacustrine. A more extensive lacustrine environment is then represented towards the top of the Strathclyde Group by a sequence of interbedded sandstone and mudstone that exceeds 1000 m in thickness and contains thin seams of oil shale that formed when the lakes were rich in algae. Subordinate lithologies present include coal, limestone (both marine and nonmarine varieties) and pale green, calcareous mudstone.

Dbk at 14:43, 29 January 2015

2015-01-29T14:43:01Z

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	'''As in the Midland Valley''', late Carboniferous to early Permian magmatism produced a large tholeiitic sill complex. This, the Whin Sill-complex, is best known as providing the foundation to Hadrian’s Wall ('''Plate P222330''') but it also appears farther south and underlies at least 4000 km<sup>2</sup> of north-east England. The complex comprises at least four individual sills, and numerous associated dykes of tholeiitic quartz-dolerite, with the main body attaining a maximum thickness of about 80 m. Radiometric dating shows the Whin Sill-complex to be around 300 million years old, a little younger than the comparable Midland Valley Sill-complex described previously.		'''As in the Midland Valley''', late Carboniferous to early Permian magmatism produced a large tholeiitic sill complex. This, the Whin Sill-complex, is best known as providing the foundation to Hadrian’s Wall ('''Plate P222330''') but it also appears farther south and underlies at least 4000 km<sup>2</sup> of north-east England. The complex comprises at least four individual sills, and numerous associated dykes of tholeiitic quartz-dolerite, with the main body attaining a maximum thickness of about 80 m. Radiometric dating shows the Whin Sill-complex to be around 300 million years old, a little younger than the comparable Midland Valley Sill-complex described previously.

			<br clear=all>
	==Bedrock Geology UK North - contents==		==Bedrock Geology UK North - contents==
	{{bedrockNorth}}		{{bedrockNorth}}

Dbk at 14:20, 29 January 2015

2015-01-29T14:20:47Z

← Older revision		Revision as of 15:20, 29 January 2015
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	'''As in the Midland Valley''', late Carboniferous to early Permian magmatism produced a large tholeiitic sill complex. This, the Whin Sill-complex, is best known as providing the foundation to Hadrian’s Wall ('''Plate P222330''') but it also appears farther south and underlies at least 4000 km<sup>2</sup> of north-east England. The complex comprises at least four individual sills, and numerous associated dykes of tholeiitic quartz-dolerite, with the main body attaining a maximum thickness of about 80 m. Radiometric dating shows the Whin Sill-complex to be around 300 million years old, a little younger than the comparable Midland Valley Sill-complex described previously.		'''As in the Midland Valley''', late Carboniferous to early Permian magmatism produced a large tholeiitic sill complex. This, the Whin Sill-complex, is best known as providing the foundation to Hadrian’s Wall ('''Plate P222330''') but it also appears farther south and underlies at least 4000 km<sup>2</sup> of north-east England. The complex comprises at least four individual sills, and numerous associated dykes of tholeiitic quartz-dolerite, with the main body attaining a maximum thickness of about 80 m. Radiometric dating shows the Whin Sill-complex to be around 300 million years old, a little younger than the comparable Midland Valley Sill-complex described previously.

			==Bedrock Geology UK North - contents==
			{{bedrockNorth}}


	[[Category:Bedrock Geology UK North\| 06]]		[[Category:Bedrock Geology UK North\| 06]]

Dbk: /* Pennine Basin of Northern England */

2014-06-19T08:47:58Z

Pennine Basin of Northern England

← Older revision		Revision as of 09:47, 19 June 2014
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	'''The deltaic lithofacies that dominates''' the Namurian succession spread progressively southwards to eliminate the extensive carbonate reefs, although thin beds of black, calcareous mudstone mark recurring marine incursions and provide invaluable stratigraphical correlatives. Towards the centre of the Pennine Basin, around the Askrigg Block, stacked deltaic sandstone bodies dominate the succession and comprise the Millstone Grit Group (C4). The ‘Millstone Grit’ is typically a coarse-grained, arkosic sandstone. It was deposited through the repeated progradation of deltas into relatively deep water and thickens southward to over 1200 m. Thin delta-top sequences show the sandstone fining upwards into mudstone, associated commonly with seatearth and more rarely with beds of limestone, coal and ironstone.		'''The deltaic lithofacies that dominates''' the Namurian succession spread progressively southwards to eliminate the extensive carbonate reefs, although thin beds of black, calcareous mudstone mark recurring marine incursions and provide invaluable stratigraphical correlatives. Towards the centre of the Pennine Basin, around the Askrigg Block, stacked deltaic sandstone bodies dominate the succession and comprise the Millstone Grit Group (C4). The ‘Millstone Grit’ is typically a coarse-grained, arkosic sandstone. It was deposited through the repeated progradation of deltas into relatively deep water and thickens southward to over 1200 m. Thin delta-top sequences show the sandstone fining upwards into mudstone, associated commonly with seatearth and more rarely with beds of limestone, coal and ironstone.

	[[Image:GS1039.jpg\|thumb\|200px\|Deep-water, hemipelagic limestone with thin mudstone interbeds from the Craven Group (Bowland Shale Formation), Scarlett Point, Isle of Man. GS1039.]]'''Around the Askrigg Block the dominantly''' clastic Namurian sequence conformably succeeds a late Visean Yoredale Group sequence but, to the south and west of the Lake District Block, the distinctive calcareous mudstone of the Craven Group (C3) intervenes, spanning the Visean–Namurian boundary. The mudstone sequence includes thin interbeds of sandstone and bioclastic limestone. The latter accumulated through hemipelagic fall-out in deep water well ahead of the advancing deltas, whence sporadic turbidite flows introduced the sandstone interbeds. In south Cumbria and the Isle of Man ('''~~Plate 52~~''') the group is relatively limestone-rich and, respectively, only about 100 and 250 m thick. Included with the Isle of Man sequence is a thickness of about 50 m of volcaniclastic debris flows that include large rafts of basaltic pillow lava. Southwards, into the Craven Basin and beyond, the thickness of the Craven Group increases dramatically to more than 5000 m. Limestones developed locally on structural highs within the basin and are assigned to the Bowland High Group (C3).		[[Image:GS1039.jpg\|thumb\|200px\|Deep-water, hemipelagic limestone with thin mudstone interbeds from the Craven Group (Bowland Shale Formation), Scarlett Point, Isle of Man. GS1039.]]'''Around the Askrigg Block the dominantly''' clastic Namurian sequence conformably succeeds a late Visean Yoredale Group sequence but, to the south and west of the Lake District Block, the distinctive calcareous mudstone of the Craven Group (C3) intervenes, spanning the Visean–Namurian boundary. The mudstone sequence includes thin interbeds of sandstone and bioclastic limestone. The latter accumulated through hemipelagic fall-out in deep water well ahead of the advancing deltas, whence sporadic turbidite flows introduced the sandstone interbeds. In south Cumbria and the Isle of Man ('''GS1039''') the group is relatively limestone-rich and, respectively, only about 100 and 250 m thick. Included with the Isle of Man sequence is a thickness of about 50 m of volcaniclastic debris flows that include large rafts of basaltic pillow lava. Southwards, into the Craven Basin and beyond, the thickness of the Craven Group increases dramatically to more than 5000 m. Limestones developed locally on structural highs within the basin and are assigned to the Bowland High Group (C3).

	'''By Westphalian times''', the region had evolved into a low-lying landscape of rivers and lakes atop a major delta system. Lush equatorial vegetation was supported but there were still periodic marine inundations. In this environment the Pennine Coal Measures Group (C5–7) accumulated. It was originally deposited in a broad, continuous basin but subsequent tectonism and erosion has isolated the Coal Measures into separate coalfields where up to about 1000 m of strata are preserved. Cyclic sedimentation prevailed and has resulted in a sequence of cyclothems that individually range up to about 10 m thick. The base of each cycle is marked by a mudstone, usually nonmarine, above which there is an upwards and alternating progression from sandstone to mudstone, with an overlying assemblage of seatearth, coal and, in places, ironstone. The Pennine and Scottish coal measures groups are lithologically similar, and share a common origin, but their stratigraphical correlation is not precise.		'''By Westphalian times''', the region had evolved into a low-lying landscape of rivers and lakes atop a major delta system. Lush equatorial vegetation was supported but there were still periodic marine inundations. In this environment the Pennine Coal Measures Group (C5–7) accumulated. It was originally deposited in a broad, continuous basin but subsequent tectonism and erosion has isolated the Coal Measures into separate coalfields where up to about 1000 m of strata are preserved. Cyclic sedimentation prevailed and has resulted in a sequence of cyclothems that individually range up to about 10 m thick. The base of each cycle is marked by a mudstone, usually nonmarine, above which there is an upwards and alternating progression from sandstone to mudstone, with an overlying assemblage of seatearth, coal and, in places, ironstone. The Pennine and Scottish coal measures groups are lithologically similar, and share a common origin, but their stratigraphical correlation is not precise.

Dbk: /* Pennine Basin of Northern England */

2014-06-19T08:46:03Z

Pennine Basin of Northern England

← Older revision		Revision as of 09:46, 19 June 2014
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	'''The deltaic lithofacies that dominates''' the Namurian succession spread progressively southwards to eliminate the extensive carbonate reefs, although thin beds of black, calcareous mudstone mark recurring marine incursions and provide invaluable stratigraphical correlatives. Towards the centre of the Pennine Basin, around the Askrigg Block, stacked deltaic sandstone bodies dominate the succession and comprise the Millstone Grit Group (C4). The ‘Millstone Grit’ is typically a coarse-grained, arkosic sandstone. It was deposited through the repeated progradation of deltas into relatively deep water and thickens southward to over 1200 m. Thin delta-top sequences show the sandstone fining upwards into mudstone, associated commonly with seatearth and more rarely with beds of limestone, coal and ironstone.		'''The deltaic lithofacies that dominates''' the Namurian succession spread progressively southwards to eliminate the extensive carbonate reefs, although thin beds of black, calcareous mudstone mark recurring marine incursions and provide invaluable stratigraphical correlatives. Towards the centre of the Pennine Basin, around the Askrigg Block, stacked deltaic sandstone bodies dominate the succession and comprise the Millstone Grit Group (C4). The ‘Millstone Grit’ is typically a coarse-grained, arkosic sandstone. It was deposited through the repeated progradation of deltas into relatively deep water and thickens southward to over 1200 m. Thin delta-top sequences show the sandstone fining upwards into mudstone, associated commonly with seatearth and more rarely with beds of limestone, coal and ironstone.

	'''Around the Askrigg Block the dominantly''' clastic Namurian sequence conformably succeeds a late Visean Yoredale Group sequence but, to the south and west of the Lake District Block, the distinctive calcareous mudstone of the Craven Group (C3) intervenes, spanning the Visean–Namurian boundary. The mudstone sequence includes thin interbeds of sandstone and bioclastic limestone. The latter accumulated through hemipelagic fall-out in deep water well ahead of the advancing deltas, whence sporadic turbidite flows introduced the sandstone interbeds. In south Cumbria and the Isle of Man ('''Plate 52''') the group is relatively limestone-rich and, respectively, only about 100 and 250 m thick. Included with the Isle of Man sequence is a thickness of about 50 m of volcaniclastic debris flows that include large rafts of basaltic pillow lava. Southwards, into the Craven Basin and beyond, the thickness of the Craven Group increases dramatically to more than 5000 m. Limestones developed locally on structural highs within the basin and are assigned to the Bowland High Group (C3).		[[Image:GS1039.jpg\|thumb\|200px\|Deep-water, hemipelagic limestone with thin mudstone interbeds from the Craven Group (Bowland Shale Formation), Scarlett Point, Isle of Man. GS1039.]]'''Around the Askrigg Block the dominantly''' clastic Namurian sequence conformably succeeds a late Visean Yoredale Group sequence but, to the south and west of the Lake District Block, the distinctive calcareous mudstone of the Craven Group (C3) intervenes, spanning the Visean–Namurian boundary. The mudstone sequence includes thin interbeds of sandstone and bioclastic limestone. The latter accumulated through hemipelagic fall-out in deep water well ahead of the advancing deltas, whence sporadic turbidite flows introduced the sandstone interbeds. In south Cumbria and the Isle of Man ('''Plate 52''') the group is relatively limestone-rich and, respectively, only about 100 and 250 m thick. Included with the Isle of Man sequence is a thickness of about 50 m of volcaniclastic debris flows that include large rafts of basaltic pillow lava. Southwards, into the Craven Basin and beyond, the thickness of the Craven Group increases dramatically to more than 5000 m. Limestones developed locally on structural highs within the basin and are assigned to the Bowland High Group (C3).

	'''By Westphalian times''', the region had evolved into a low-lying landscape of rivers and lakes atop a major delta system. Lush equatorial vegetation was supported but there were still periodic marine inundations. In this environment the Pennine Coal Measures Group (C5–7) accumulated. It was originally deposited in a broad, continuous basin but subsequent tectonism and erosion has isolated the Coal Measures into separate coalfields where up to about 1000 m of strata are preserved. Cyclic sedimentation prevailed and has resulted in a sequence of cyclothems that individually range up to about 10 m thick. The base of each cycle is marked by a mudstone, usually nonmarine, above which there is an upwards and alternating progression from sandstone to mudstone, with an overlying assemblage of seatearth, coal and, in places, ironstone. The Pennine and Scottish coal measures groups are lithologically similar, and share a common origin, but their stratigraphical correlation is not precise.		'''By Westphalian times''', the region had evolved into a low-lying landscape of rivers and lakes atop a major delta system. Lush equatorial vegetation was supported but there were still periodic marine inundations. In this environment the Pennine Coal Measures Group (C5–7) accumulated. It was originally deposited in a broad, continuous basin but subsequent tectonism and erosion has isolated the Coal Measures into separate coalfields where up to about 1000 m of strata are preserved. Cyclic sedimentation prevailed and has resulted in a sequence of cyclothems that individually range up to about 10 m thick. The base of each cycle is marked by a mudstone, usually nonmarine, above which there is an upwards and alternating progression from sandstone to mudstone, with an overlying assemblage of seatearth, coal and, in places, ironstone. The Pennine and Scottish coal measures groups are lithologically similar, and share a common origin, but their stratigraphical correlation is not precise.

Dbk at 08:41, 19 June 2014

2014-06-19T08:41:35Z

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			__NOTOC__
	{{BedN}}		{{BedN}}
	==359 to 299 million years ago==		==359 to 299 million years ago==

Dbk: Protected "Bedrock Geology UK North: Carboniferous" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite)) [cascading]

2014-06-11T12:21:16Z

Protected "Bedrock Geology UK North: Carboniferous" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite)) [cascading]

← Older revision	Revision as of 13:21, 11 June 2014
(No difference)

Dbk: /* Midland Valley of Scotland */

2014-05-21T12:54:10Z

Midland Valley of Scotland

← Older revision		Revision as of 13:54, 21 May 2014
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	'''Widespread, intermittent volcanism''' continued from the late Visean into the early Namurian, producing mostly mafic lava but with some volcaniclastic components. One major volcanic sequence that built up in the central and eastern parts of the Midland Valley, the Bathgate Group, may be as much as 1000 m thick and formed a partial barrier between sedimentary systems that persisted until well into Namurian times.		'''Widespread, intermittent volcanism''' continued from the late Visean into the early Namurian, producing mostly mafic lava but with some volcaniclastic components. One major volcanic sequence that built up in the central and eastern parts of the Midland Valley, the Bathgate Group, may be as much as 1000 m thick and formed a partial barrier between sedimentary systems that persisted until well into Namurian times.

	<gallery ~~mode~~=~~"packed"~~>		<gallery widths=200px>
	Image:P064459.jpg\|The lavas of the Clyde Plateau Volcanic Formation (Strathclyde Group) form prominent 'trap features' on the scarp face of the Gargunnock Hills, near Stirling. P064459.		Image:P064459.jpg\|The lavas of the Clyde Plateau Volcanic Formation (Strathclyde Group) form prominent 'trap features' on the scarp face of the Gargunnock Hills, near Stirling. P064459.
	Image:P001097.jpg\|Tuffs from the lower part of the Garleton Hills Volcanic Formation (Strathclyde Group) at Seacliff Harbour, near North Berwick, East Lothian, with the associated volcanic plug of the Bass Rock in the background. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=2395&index=0&total=1&view=viewSearchItem P001097.]		Image:P001097.jpg\|Tuffs from the lower part of the Garleton Hills Volcanic Formation (Strathclyde Group) at Seacliff Harbour, near North Berwick, East Lothian, with the associated volcanic plug of the Bass Rock in the background. [http://geoscenic.bgs.ac.uk/asset-bank/action/viewAsset?id=2395&index=0&total=1&view=viewSearchItem P001097.]

Dbk: /* 359 to 299 million years ago */

2014-05-20T08:54:28Z

359 to 299 million years ago

← Older revision		Revision as of 09:54, 20 May 2014
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	==359 to 299 million years ago==		==359 to 299 million years ago==

	[[Image:P785810.jpg\|thumb\|200px\|[P785810.]]		[[Image:P785810.jpg\|thumb\|200px\|P785810.]]
	'''By early Carboniferous times Britain''' formed part of the southern margin of Laurussia and was situated in southern tropical latitudes; it drifted northwards during the remainder of the period to lie just north of the Equator. An initially arid climate became progressively more hot, humid and wet during that northward drift, and then reverted towards the end of the period. The tectonic regime was broadly extensional, with dextral strike-slip becoming progressively more important, particularly so in the Midland Valley of Scotland. The result was a sedimentary pattern controlled by basins and blocks of more or less subsidence. The blocks are characterised by thin and incomplete sedimentary successions. The basins were filled with thick and largely complete successions. They are commonly orientated north-north-east and in the Midland Valley are associated with growth synclines controlled by dextral strike-slip faulting. Intermittent volcanic activity, most notably in the Midland Valley, produced substantial lava fields locally, with related intrusion of sills, dykes and plugs.		'''By early Carboniferous times Britain''' formed part of the southern margin of Laurussia and was situated in southern tropical latitudes; it drifted northwards during the remainder of the period to lie just north of the Equator. An initially arid climate became progressively more hot, humid and wet during that northward drift, and then reverted towards the end of the period. The tectonic regime was broadly extensional, with dextral strike-slip becoming progressively more important, particularly so in the Midland Valley of Scotland. The result was a sedimentary pattern controlled by basins and blocks of more or less subsidence. The blocks are characterised by thin and incomplete sedimentary successions. The basins were filled with thick and largely complete successions. They are commonly orientated north-north-east and in the Midland Valley are associated with growth synclines controlled by dextral strike-slip faulting. Intermittent volcanic activity, most notably in the Midland Valley, produced substantial lava fields locally, with related intrusion of sills, dykes and plugs.