Talk:Insular Islands

"Today"

Are these the precursors to the Insular Mountains or the Coast Mountains? The article should say so, or which geological belt they're now part of.Skookum1 (talk) 18:05, 3 November 2009 (UTC)

From what I understand, the rocks from the Insular Islands collision form the Insular Belt, which includes the Insular Mountains. BT (talk) 00:10, 4 November 2009 (UTC)

origin of Insular islands ?

The Insular islands migrated towards North America for about ~200Myr. At an average tectonic plate speed of ~10cm/yr (=100km/Myr), they migrated ~20,000km, or approximately 180 degrees of longitude. Now, that amazing amount of migration is actually possible. For, reconstructed maps, for earth in the Carboniferous period, show that the ancient paleo-Pacific ocean spanned ~210 degrees of longitude. Thus, the Insular islands perhaps imply the location, of the ancient paleo-east-Pacific-rise, back in the mid-Carboniferous period. If so, then the ancient paleo-Pacific Mid-Ocean-Ridege was located about ~30 degrees (several thousand km) east of the ancient North China terrain. Inexpertly, the ancient spreading ridge may even have separated North China from the Insular islands; however, against that possibility, North China was obducting oceanic crust, emerging from the west side, of the paleo-Pacific spreading ridge; and opening oceans, deriving from prior continental rifting, e.g. Atlantic ocean, do not subduct under the very land-masses previously rifted apart (the young sea floor grows onto the margins of the continents). But the Insular islands were plausibly an equatorial island-like terrain, geographically near ancient North China. That would explain the presence of fossil foraminifera in the Insular terrains, that resemble those from ancient south-east Asia (according to the Open University textbook Earth's Engine). 66.235.38.214 (talk) 07:27, 9 October 2012 (UTC)

http://upload.wikimedia.org/wikipedia/commons/0/04/LateCarboniferousGlobal.jpg http://www.askaboutireland.ie/aai-files/assets/libraries/an-chomhairle-leabharlanna/reading-room/physical-landscape/carboniferous-glaciation.jpg

As indicated in the second cited figure above, from 550-350Mya (Cambrian, Ordovician, Silurian, Devonian), China (north, south, plus Malaysia) was connected to Australia. But, by about 350Mya, a rift had started separating the former from the latter. Ergo, seemingly not impossibly nor implausibly, that spreading zone rift, which separated off Australia, may also have separated off the Insular islands. If so, then the Insular islands were originally part of north China, and were rifted off c.350Mya, beginning a 200Myr migration eastwards, as ancient southeast Asia was rifted off of Gondwana. 66.235.38.214 (talk) 07:53, 9 October 2012 (UTC)

From my understanding, the Insular Islands were formed by volcanic activity at a subduction zone, not rifted off a continent or some other landmass. A tectonic plate speed of 10 cm per year is faster than most if not all modern tectonic plates. Volcanoguy 08:10, 9 October 2012 (UTC)

From my swift skimming, of the Burke museum website (cited in the Wiki article), the Insular islands were formed in the Carboniferous; and were "swept up" by North America, in the Cretaceous. i offer the following figures, for a potential "growing rift" scenario, according to which, the Insular islands were once part of northern China (350Mya), and were rifted off by a spreading ridge, which worked its way around the world, over the aeons from then until now, presently persisting as the mid-Atlantic/Arctic ridge:

http://imageshack.us/a/img29/4546/insularislands400200mya.png

http://imageshack.us/a/img802/3249/insularislands20050mya.png

i understand, that earth Tectonic plate speeds range from 3-16cm/year, which averages out to about 10cm/year. Please peruse the pictures; the yellow circles, in the Indian ocean, from the Cretaceous, are the Kerguelen & Reunion hotspots. Tangentially, volcanic piping being malleable, perhaps the Kerguelen hot-spot "budded" or "fissioned" off the Reunion hot-spot 65Mya? Or, perhaps the Reunion represented a second "melt thru" from the same hot-spot plume? Perhaps, too, 45Mya, the Reunion piping clogged, and for some reason, the volcanic zone, which had been residing on the ridge-top, was carried westward down-slope, "sputtering" with occasional "flare ups" of activity, as seen over the last 10Myr? 66.235.38.214 (talk) 11:46, 9 October 2012 (UTC)

i redid the "plates plot" for 200-50Mya, extrapolating from current subduction zones, to retrodict additional ancient plate boundaries. i offer, that the ancient "proto-Atlantic/Arctic" spreading ridge subducted under Asia (150Mya), and "rolled" under Asia's deep lithosphere (150-50Mya), eventually "popping back up" on the other side of Asia, in the Arctic (50 May); and that, compressed from the Arctic, Asia started driving southeastwards, obducting Pacific plate. Slab-pull force then started dragging the Pacific plate northwestwards, accounting for the bend in the Emperor-Hawaii island chain.

http://imageshack.us/a/img838/3249/insularislands20050mya.png

66.235.38.214 (talk) 13:58, 9 October 2012 (UTC)

Added Philippine plate (back-arc spreading ridge behind Australia/Pacific plate boundary, first "bulldozed" north by Australia, then west by Pacific plate). Young Philippine plate is denser than Asian continent, lighter than older Pacific plate basin. Also added African rift (India converged towards Arabia, grinding together, and driving Arabia northwards, rifting off the Arabian corner of Africa). Judging from guestimated plate boundaries, India was mired amidst its own slender section of Tethys Sea plate; when Asia obducted the Tethys spreading ridge, Africa was (slab-)pulled northwards, but smaller India, on a smaller slab, would seemingly plausibly have been accelerated northwards more? 66.235.38.214 (talk) 15:27, 9 October 2012 (UTC)

http://imageshack.us/a/img441/3249/insularislands20050mya.png

Please ponder Antarctica "down" on earth's south pole. Imagine that some oceanic plate, e.g. Charcot plate, subducts under Antarctica; "slices under" the continent. Could not a large subducting slab "slice off" Antarctica, re-emerging at earth's surface, on the other side of Antarctica? Could not a subducting slab "scalp off" the souther polar regions, isolating Antarctica?? 66.235.38.214 (talk) 15:44, 9 October 2012 (UTC)

Flood basalts often result from rifting. The Insular Islands seem (from fossils) to have originated near archaic China; c.260Ma large-scale flood basalts produced the Emeishan Traps; nearly 150Myr later, the Insular Islands accreted onto western North America. Perhaps the Emeishan Traps reflect rifting, resulting from which, the Insular Islands were separated from archaic China ?? 66.235.38.214 (talk) 17:03, 19 October 2012 (UTC)