Fig.0. Madagascar to Africa fit. (a) Looks good to me. (b) Looks even better. [Added as an afterthought to the post below in case it wasn't clear what I meant by the juxtaposed continental margins looking a bit iffy.] Superficially the split looks good, as in (a), but when the geology is taken into acount the waterline itself won't do, .. because the build-up of stratigraphic sequence over time has to be taken into account (b); see Fig.4 below).
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Hmmm...
(... Still harping on about the importance of letting the data speak for itself, rather than being guided by theories), .. the fit of Madagascar to Africa provides us with a good case in point, .. because did it? I mean, fit? .. once upon a time?
This example illustrates the criticism that Wegener faced in relation to the Atlantic in a nutshell, but these days we are in a much more foward position to answer the question. Continental shapes are much more readily accepted as indicative of crustal rupture than in Wegener's day, and spreading ridges and transform faults are accepted too as indicative of the trace of continental separation. This adds much to the arsenal of 'facts' that that may be brought to bear on the question, .. the 'facts' are no longer 'hypotheses'.
Nevertheless, in regard to Madagascar and Africa (and India) and in a context of Plate Tectonics and Earth expansion there does remain some aspects of theory in regard to where Madagascar might once have fitted. Certainly Madagascar is a crustal fragment, and there are geological similarities with Africa (and India), .. biological similarites too, and clearly (given what we know of spreading ridges) the Indian ocean was once closed. So where precisely did Madagascar fit in the jigsaw puzzle?
Best Plate Tectonic practice using the objectified data of palaeomagnetism and the geophysical black box puts it in what is called the "northern position" (Fig.1), with consequences for the entire population of continents waiting to grow into so-called plates to the east and south in the figure,
Fig.1. Madagascar - Africa fit according to Plate Tectonics best practice can-o'-worms palaeomagnetism, in what is known as the 'northern position' (about 2,500km further north of the "southern position'). (Image courtesy of http://www.scotese.com/satlanim.htm .)
Fig.2. Alternative fits of Madagascar to Africa. 1. = Northern position (according to the 'objectified data of palaeomagnetism' and consensus Plate Tectonics); 2. = southern position ( according to the subjective, opinionated, non-scientific correlation of geology and Earth expansion here). (Click the image for a bigger figure; geology courtesy of UNESCO world map.)
See how 'science' is done? And why geology gets such a bad rap? You're supposed to distance yourself from the data, .. "objectify" it. Put it in the box, shake it, close your eyes, and Lo! the box will speak. Using your head (a.k.a. 'common sense) is not considered 'science'. You have to 'measure it' to make it 'science', then theorise what it means. That way you're ok, according to 'The Method'.
[ Bloody 'Method' actors, .. doing Plate Tectonics.. ]
Now, .. I would agree with that (about measuring being science). There's nothing scientific about common sense though. Common sense is the destination at which science hopes to arrive. Through the application of science, puzzles become common sense, self-evident truths. Commonsense transcends 'The Method'. And that's what geology boils down to with its commonsense ('Pssst') Principles of Stratigraphic and Structural Superposition shouting clues in our ear, by which commonsense application all is revealed, if we just keep our hypotheses and theories out of the way - Common Sense Rules.
So let's see how we get on with some anti-science commonsense (Fig.3).
Fig.3. Anti-science common sense revealed. The fit of Madagascar and Africa according to commonsense Geology and Earth expansion. Is seamless. The detachment from Africa, which is axial to the syncline (blue-and-green "boomerang'', bounded by blue) at the southern extremity of the Great African Rift Valley, is hardly detectable. (Blue = Jurassic, Green = Cretaceous; mixed sediments and volcanics) Geology courtesy of UNESCO.
It's obvious, .. it's where it all happened. No need for 'supporting' palaeomagnetics - which are not supporting at all. Just like day and night are perfectly explicable to our space traveller in terms of shadow cast by a spinning Earth, and an avalanche burying the village (rather than a village rushing under the mountain) is explicable from the vantage of distance, so too it is perfectly obvious that Madagascar has separated from Africa along the axis of the syncline in the southern position - palaeomagnetic 'evidence' or not.
Anyway, hidden in those measurements taken to "objectify the data" and purge it of all subjective influence is the randomising effects of surficial slumping and other crustal rotations that happened since the Curie point was frozen in the rocks, not the least of which are the trials and tribulations of trying to collect orientated samples in the first place (or worse, have others collect them for you). I reckon it's a wonder palaeomagnetic data even places Madagascar anywhere *near* Africa, .. which 'northerly position' makes me seriously suspect further finagling and cooking of the data. (... )
(Geology?) .. it's how it maps out that counts, .. how 'the data' is contextualised - scale and time and all that, .. not what you 'measure' (with all its inherent uncertainties) at a specific field location.
Fig.4 Near retrofit of Madagascar to Mozambique. Lighter colours (= Tertiary sediments) infill the 'scar' created as Madagascar recedes from Africa - or rather Africa recedes from Madagascar - is about 350-400km. Tertiary sediments filling the gap reflect falling sea-level /local isostatic correction as the Earth gets bigger. Note the ENE-WSW move is reflected in structure that spans from pre-Jurassic times (the intracratonic syncline of Jurassic volcanics preserved to the west) to post-Tertiary times (parallel coastlines) (Image base courtesy of Google Earth, geology courtesy of UNESCO.)
So there we have it, .. the simple commonsense, no-hypothesis needed, non-scientific ("Pssst"-in-your ear) picture : Madagascar as a crustal fragment detached from Africa as the Indian Ocean opened, and part of a much larger picture of crustal dilation. It fits, .. with the proviso that it overlaps some 400-450km of the Mozambique coast.
Which (overlap) is a nicety that would have scuppered Wegener totally at the time, because there is no coastline fit here whatsoever, .. but the geology , sequenced in time, fits very well. (Ask mother.)
[Added, 2012-09-15. (Loose talking here). I meant there is no fit of that syncline ('banana') with the coastline, so I guess I shouldn't say that, about "no coastline fit whatsoever", because the actual coastline of Neogene (yellow) and Quaternary (buff colour) sediments fits quite well with the banana, .. which shows the importance of flat detachments, basin subsidence and isostatic rebound of the pull-aparts.]
How many more suchlike overlaps (/duplications) (/isostatic adjustments) are hidden in the stratigraphic sequence, that support Earth expansion, and belie Plate Tectonics?
Lots. It's the whole story of geology that is yet to be properly contextualised, and has universally been overlooked; an Earth that is getting bigger.
Fig.5. Madagascar and Africa separation in relation to India is shown by the arrow, the trace of transforms in upper mantle between Madagascar and the Seychelles, those of the spreading ridge more generally, and the paired banks of the Seychelles and the Maldives representing an ancient position of Madagascar and India across the ridge. (Click for a bigger figure.)
In terms of global context, geology has hardly begun. And, .. since it's telling us the Earth is getting bigger, .. neither has physics. [link added 20170417; about 9:10 in, where she says, "It looks like we're going to have to start over", and he says, "Ya-ya."]
( Commonsense, .. see? )
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[Added below, .. 2012-09-16 in answer to Anonymous, ..September 11, 2012 8:15 PM ]
(More on the Madagascar fit.)
Fig.6. More on the Madagascar fit. Bad and jangly on the left, smooth and good on the right. (Click image for a bigger one.)
Bad on the left. Is based on a common misunderstanding what transform faults are all about (Mental note to deal with later.) Transform faults are the trace of spreading *along* the ridges as much as they are *across* the ridge. The red interpretation denies the obvious structural connections in regard to the Great Rift Valley /African coast /Madagascar separation /Indian connection illustrated by Good on the Right. (And a whole lot more in the global context.) The Mozambique Basin (white) is the scar left on the mantle as Africa shimmied to the left on flat structures when it detached ("un-docked") from India, leaving the Moz. and Mad. Plateaus also as scars - which is why the left /south side of spreading on the Indian Ocean Ridge is more than on the north /right side. In other words, Africa probably separated from India, rather than the other way round, leaving the Seychelles and Madagascar in its wake. Similarly the Indian coast has shifted too from the Mascarene / Laccadives ridges.
Fig.7. Madagascar Separation according to the Davie Fracture Zone (a.k.a. "The Garden Path.") This is a classic example of thinking in a lobotomised way about detail ..that sees villages rushing under mountains, rather than looking with cognitive connection at the larger picture as in Fig.6 green above. (Reference : - Fig.1 :- http://www.sciencedirect.com/science/article/pii/S1464343X05002220
[Further update 2012-10-04 ]
Fig8. Gravity signature. The 'Davie Fracture Zone' (Fig.7) is paired here with the Mozambique Escarpment to the west (yellow lines in (a) ). The rift separating Madagascar from Africa is a 'doppelganger' of the African Rift Valley to the west, and the Indian Ocean spreading Ridge to the east. (Click the image for a bigger figure.)
[Added 20180731 - "Fudge"]
[Added 20180905 :=: [Added 20180905 :=:
[Added 20180905 :=: Correlation Madagascar to Western Ghats, India ]
7 comments:
I always find you discussions of interest, and dedicated to an direct and honest appraisal of evidence. I would appreciate your comments regarding this image from gEarth with ocean floor age overlay. http://i46.tinypic.com/2mwuzgn.jpg
It would seem to imply the north position is correct without impeding the "commensense" approach of earth expansion. India seems more the constructive case, since its accepted scurry across the ocean floor has always seemed so wrong and singularly so. JP
Hi JP, .. Just noticed your comment as I was about to post the added image (Fig.0). Yes, it does imply a northerly position, but you have to look beneath the nice colours and the 'ages' they imply. I don't buy it. Sure there's a Google Earth line on the ocean floor trailing down from the Horn of Africa, and another parallel, trailing down from Ethiopia to the south of Madagascar. That's the dislocation that split the M. Plateau to the south, where the movement vector was also northeasterly. Transform faults (as at the spreading ridge to the south) don't just indicate movement away from the ridges, but along them as well. [I'll put up another image later.] I see no trace of a ridge between Madagascar and Ethiopia, and you would have to question therefore the reliability of the data underlying those colours.
Look real nice don't they? (They're supposed to.) But just how much dredging goes on these days, .. and who's paying for it? And how much?
It very much impedes Expansion though, .. since it completely screws up the fit of all those continents to the east and south in Fig.1 .."waiting to grow into plates." I think they fit better.
:-))
See also Addendum, 2012-09-16, interpreting the Mozambique Basin as a mantle scar left by the westwards drift of Africa relative to mantle spreading.
I really am impressed by the close fit in this southern position! The blue and burgundy rocks in East Africa match those blue and burgundy rocks in Madagascar perfectly!
Indeed those rocks in West Africa belong to the Lobombo (N-S tending) and Mateke-Sabi (ENE-WSW trending) monoclines. They are volcanic rocks erupted between 181 and 178 million years ago in the Jurassic, and form the volcanic rifted margin of East Africa. They have been Called the 'Karoo' volcanic complex and are made up primarily of Basalts and Rhyolites.
YES - I did say this is the continental margin! It was shown by Watts (2001) that the Mozambique Coastal Plane is underlain by oceanic crust, similar to the Niger Delta in West Africa! It would seem that there is in fact no coastal overlap in your reconstruction after all... Brilliant! please refer to Klausen (2009) for further enlightenment.
The same colored rocks in Madagascar belong again to a 'Karoo' sequence. These are the Karoo sediments, deposited between the Gzhelian (Uppermost Carboniferous, ~300 million years ago) and possibly all the way up to the Aalenian (Middle Jurassic, ~170 million years ago) during a complicated and extensive period of intracontinental rifting prior to the breakup of Gondwana. They are primarily made up of Conglomerates, Sandstones, siltstones and a few limestones.
So we have two 'Karoo' sequences reunited, the blue's and burgundy's fit perfectly together! On the West we have Volcanic rocks erupted dramatically over as much as 3 million years, and on the East we have Sedimentary rocks slowly deposited over maybe 130 million years... :)... Oh, wait... :/... They don't match, in fact, they're nothing alike! The only thing remotely similar about them is their name 'Karoo', and thus the color on the map. What a F***ing Cop-Out this is!
For your information the oceanic crust underlying the Mozambique Coastal Plane actually belongs to the paleoposition of the Mozambique Rise, not Madagascar. Madagascar has a snug fit to the north juxtaposed against other 'Karoo' sediments of the East African Selous and Mombasa basins and the Lamu embayment. Please read: Eagles and konig (2008) and Reeves (2014) for clarification on this.
Anonymous - Thanks for your comment.
So you want to keep Madagascar in the northern Position?
***I really am impressed by the close fit***
That's very good. So am I. So they do.
***the Mozambique Coastal Plane is underlain by oceanic crust.***
Sure. That's the point of the reconstruction. Though it was a guess. (I go simply on the morphotectonics of the ocean floors (+ divining rods). It's also the point of the volcanics of the belt too. It's what the mantle does when the crust on top breaks - Dykes, volcanoes, and sundry igneous complexes. That African margin is a long-lived and complex affair (Bushveldt; Great Dyke and sundry related etceteras - then the ocean floor). (Something to do with erosion and exhumation of the crust..)
***No coastal overlap in your reconstruction after all (?)***
But there is (in mine). I know others would rather Madagascar fits the northern position according to the Davy fracture lines, but I don't think it does. I think we're looking at different levels of dislocation, with Africa-Mad.- India on top and the substrate (Madagascar Ridge / Antarctica and extending back up to Saudi Arabia) pulling out from underneath. Upper level going NE, Lower level going NS. I reckon anyway. The relationship of the two levels is easily seen off the southern end of Africa on Google Earth, and clarified in their relation to the SWIOR. So no problem with the southern position. .
*** "What a F***ing Cop-Out this [colours and names] is.." ***
(I know, but it's the best that technology could do back then - Flat maps, .. Flat 'Plates'. Flat Tectonics. It's a whole new ball-game today of course and we wait for global geology to catch up and have the spherical context it deserves. Google Earth is great (Aiyee !), though I see the satellite gravity has been blaniked out for the continents recently, leaving just the ocean floors. Maybe somebody's working on it (at last), and keeping it all to themselves (like they did the last time).
But why would you expect them to be similar? Crustal rupture and volcanic extrusion is a relatively brief affair. Crustal adjustment (erosion /sedimentation, gravitational stabilisation) goes on for much longer. It's still going on (witness erosion profiles of Africa) (matching Madagascar).
***Oceanic crust underlying the Mozambique Coastal Plane actually belongs to the paleoposition of the Mozambique Rise, not Madagascar. ***
Sure it does too. It's all the same thing, just different displacements at different levels. 1. according to the construction here, 2 (deeper) according to the separation of Antarctica from the Rodriguez Triple position extending northwards. ( bi-directional spreading across flat /listric dislocations in laminated crust). No contradiction there. It's the hallmark of expansion.
***Snug fits.***
Southern position is snugger. Makes more sense too. (imo.) Hope it doesn't interfere too much with any licence application, if there is one. It would certainly give "drilling in the wrong spot " some celebrity , ..some flamboyance, ..some style.
Adam/Earth was expelled from Eden/Aten/Sol. As Earth left the star, it left the massive Z Pinch, that normally compresses everything inside the sun.
Earth was released from this pressure, gradually. In a matter of minutes, that is. The first spot, on the surface of the planet to experience this is now buried under the Himalaya/Tibetan Plateau. The first spot immediately burst upwards, like fizzy pop released from a shaken bottle. This resolved into Eve, in a matter of hours. Our moon! As the rest of Earth/Adam penetrated the Z pinch, those areas and volumes also expanded, but to nowhere the same degree.
In fact, much of the expansion was sideways, into the vast hole left by the Eve eruption. This is why much of what lies, deep, under that area is mostly water. Instead of this salty extremely hot water outgassing, it burst sideways and was then trapped by the failure of the Eve column, as the expansion passed onto the rest of the planet.
The crust of Adam was less dense than the magma underneath. It was also cooler and more cohesive. So, it was dragged, for hundreds of kilometres, towards the Eve spot. After many seconds, the upwelling had shot through the crust, the cohesion was lost and it fell to the earth.
We can see the island chains and sea mounts all around Asia, the failed anchors of this crust. We can discern the outlines of todays Asian/Indian crust if we look!
The Sceptre is Adam with a Column ascending. The Orb is Luna/Eve/Lilith. Naturally, she got quite a bad rap for association with these events.
Linga are the memory of these events. Obelisks, Columns Pyramids all convey the same information, often exactly what was seen from where they were erected, when these (less than hour long) events occurred, less than 10,000 years ago.
Don't know about Adam and Eve. Like anthropogenic global warming it's taking homo(ec-)centricity a bit far), but I think almost certainly the Moon is implicated. And you're right about the Tibetan Plateau being a focus for special attention; the "vast hole" being now filled by the dilating Indian-Pacific oceans.
"Sideways" ? Yes, .. includes rotation off the Himalayan High to form the Western Pacific Margin and the dilation of the America Cordilleras. Catastrophic events for sure (geologically speaking). But if it was as catastrophic as you seem to be suggesting it's unlikely we'd be here talking about it.
I like the bit about the phallic symbols though, as push-back to all this hillarious anti-trump feminism we're being assailed with. Seems the Mars /Venus thing has been forever, .. not just something of the present. (Men, .. grabbing a snatch; women snatching a grab.) :-)
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