Earth's geochronology map: a work in progress...

[t00fri]

I collect points age by age and then do process them with Perl.

Massimo,

good to read that you are still using Perl. You first undertook the effort of learning it and now I am sure you are well aware of it's power

Fridger

[Fenerit]

I collect points age by age and then do process them with Perl.

Massimo,

good to read that you are still using Perl. You first undertook the effort of learning it and now I am sure you are well aware of it's power

Fridger

Well, the merit is your whether I could dealt with it for real application, being Perl known by me just as "name" of a programming language, and without to have done anything with it. As for its power I'm aware, while for its deep exploitation I'm not so sure to be able to do that with easiness. I'm still a "disgrace" as programmer.

[Aphyle2007]

...Another issue.



Seem that the Large Igneous Provinces (LIPs) as seen in the 3D geologic add-on doesn't matches with the areas ascribed to them by the geologic map; just some features at poles match. Such behaviour concern only the continental LIPs, while the oceanic ones matches perfectly with the seafloor reliefs as seen in the bathymetry map. Being in the same dataset, I've check their projections; but all is correct. Once finished the map, probably I will update the 3D LIPs by extracting the zones from such shapes; thus consider the existent LIPs model as "generic".

It would be interesting to see the definitions of the relative data sources of the continental rocks in both the LIPs and the Geologic Maps. For instance, a LIP might include the known extent of the igneous materials and units that make up the LIP, while the geologic map might include bedrock (some of which might be covered) or surface geology. The LIP might also include rocks affected by the igneous rocks, cooked through contact metamorphism, or reflect the multiple intrusions that make up the LIP. Consider also that the continental bedrock geology reflect that, on the whole, continental rocks are far more complex, and hence differentiated, than oceanic rocks. Some of the oldest rocks in the world come from the the Laurentian shield - up to 4 billion years old - so a lot can happen to cause variation. Oceanic rocks are at the start less complex and are much younger - about 240 million years, max. So what I am saying is that it is harder to get variation of extent of oceanic maps between sources/definitions, but much easier to see variation in continental maps. Merely a theory, though - take this with a grain of salt.

[Fenerit]

Hi, Aphyle2007; your remarks sounds quite reasonables, being the original purpose of the map that of:

...digitizing the geologic map was to allow us to have a geologic base on which we drew the boundaries of the geologic provinces of South America. The geologic map was used as a guide for placing province boundaries rather than as a location map for very specific geologic entities.

albeit I think is fairly enough, as long as such map concern with the whole world and not with just some areas; moreover it is free and nonetheless expandable in future toward "very specific geologic entities" through further VT levels (many world's states can be subdivided furthermore already now, being their geo maps shared for free).

Unfortunately, the Univ. of Texas's link from which I'd downloaded the LIPs dataset now seems not longer available:
http://www.ig.utexas.edu/research/projects/lips/index.htm
thus I must rely just on the zip downloaded so far; while for the geologic map and its shapes, I can share the metadata by further citation:

Attribute Definition Source: U.S. Geological Survey
Attribute Domain Values:

Enumerated Domain:

Enumerated Domain Value: Q, T, K, JK, J, TrJ, Tr, PZMZ, P, CP, C, D, S, OS, CmO, Cm, AD, PZ, APZ, Qv, Cv, Mv, Pv, PZv, MCi, PMi, Mm, PZm, pC, H2O, Ice, U, "unlabeled"
Enumerated Domain Value Definition: Range of geologic age values taken from original map legend: Q - Quaternary (undivided) T - Tertiary K - Cretaceous (undivided) JK - Cretaceous and Jurassic J - Jurassic (undivided) TrJ - Jurassic and Triassic Tr - Triassic PZMZ - Paleozoic-Mesozoic P - Permian CP - Permian - Carboniferous C - Carboniferous D - Devonian (undivided) S - Silurian OS - Silurian - Ordovician CmO - Ordovician - Cambrian Cm - Cambrian AD - Precambrian - Devonian PZ - Paleozoic APZ - Precambrian - Paleozoic Qv - Quaternary volcanics Cv - Creteceous - Tertiary volcanics Mv - Mesozoic volcanics Pv - Permian volcanics PZv - Paleozoic volcanics MCi - Mesozoic - Cenozoic intrusives PMi - Paleozoic - Mesozoic intrusives Mm - Mesozoic metamorphics PZm - Paleozoic metamorphics pC - Precambrian (undivided) Ice - Arctic areas covered by Ice H2O - Lakes and wide rivers U - Unmappedd area "" - "unlabeled"
Enumerated Domain Value Definition Source: U.S.Geological Survey

Notice that in the Celestia's map, the colors and ages have been ported conformingly to the U.S. geologic map; so the eras, for instance the paleozoic, is subdivided as lPz/mPz/uPz/Pz and thus their relevants plutonic/volcanic/metamorphic rocks' attributes.

Now, I will check this dataset:
http://georoc.mpch-mainz.gwdg.de/georoc/Entry.html
which shows the LIPs' sampled points with their extensive rock's attributes and compositions, but I do not think that it will show the points' profile which shape the flood's surface position (possibly, for another comparison), but rather just the scattered samples "inside". Finally, at least for the Paran?, the common LIPs' assessment doesn't seem to overlap it onto the early events like the proterozoic ones, which environs the south brazilian shield.
http://www.largeigneousprovinces.org/record.html

[Aphyle2007]

Now here is a corollary challenge: Because the Blakey paleocontinental maps show the continents in their respective positions through time (over the last 600 Ma), and the one site you list has an option to show them by age, what would happen if the LIPs in Lua Adds showed the LIPs on the continents in their proper position with time. So the earliest maps would show only a few LIPs and then the LIPs would build with time. The good news is that the oceanic ones would not appear until the 240 Ma map. Does this make sense?

[Fenerit]

It make sense. There is just one aspect that would have to be clarified (at least for me). It make sense as long as the recents LIPs are few displaced from the actual (nowaday) geo-map's position, indeed; since the continental drift has spent less time. The floods are shaped like were "frosted" at times, if I've well-caught the meaning of "...So the earliest maps would show only a few LIPs and then the LIPs would build with time", right? Now, premise that I'm unable to retrieve and to check the site from where I did downloaded the dataset, what that is an open question, are the oceanic LIPs; because they - too - are part of the moving plates. Thus, slighty displacements would have be on them. The only supposition I can get here, is that of them have been shaped after the Ocean Drilling Project as they are now, without to "reconstruct" their evolution. I've explored and read some parts of that site, but is too huge to read and my supposition is just a guess, though.

[Fenerit]

Hi Aphyle2007; let's forget my supposition above: here there are the screenshots of few LIPs which shows small displacements. My remarks on Paran? were done because such LIP is the most displaced from the geo-map position.

Below, the black squares are the sampled points like were in the dataset of the forementioned german link. Aside toward the gulf, the samples seems more inside the "green" than inside the "red" profile.


Afar LIP seem good:


The artic LIP are thats which match best.


Columbia River's LIP is good yet:


Finally, the Deccan's lip shows small displacements but can be hold as good even that.

[Aphyle2007]

These are interesting discrepancies that you have uncovered. On the one hand, one would expect that the older the LIP, the more differences one would see between bedrock geology and surface geology. Thus, the Columbia River and Deccan features should show close correspondence while older events, like the South American one, should show greater divergence. Then you show the Greenland ones, for which at least the western ones should be the worst in correlation, but you show that they are not. Is there any chance we could be looking at different map projections between the data sets? For instance, the Deccan feature seems similar but off-set on scale.

On the LIPs over time, I'll check with my tectonics colleague on the continental reconstructions that he has done. The problem is that many of his maps are polar rather than Mercalli-type projections. Thus, I am not sure that the data exist to automate a projection back over time to 600 Ma. One would have to hand-draw the shapes, perhaps as an overlay texture.

If you've a moment, see what the fit is for Western Scandinavia, Scotland, and Northern Ireland. These are, by and large, quite old rocks, so one would expect something a bit off.

[Fenerit]

...
Is there any chance we could be looking at different map projections between the data sets? For instance, the Deccan feature seems similar but off-set on scale.
On the LIPs over time, I'll check with my tectonics colleague on the continental reconstructions that he has done. The problem is that many of his maps are polar rather than Mercalli-type projections. Thus, I am not sure that the data exist to automate a projection back over time to 600 Ma. One would have to hand-draw the shapes, perhaps as an overlay texture.

No clues here, sorry.

If you've a moment, see what the fit is for Western Scandinavia, Scotland, and Northern Ireland. These are, by and large, quite old rocks, so one would expect something a bit off.

As for Scotland and Northern Ireland, the European part of the geo-map declares them like Tv (Tertiary volcanics)

Unfortunately, Scotland's parts are traced with points, aren't well visible.

Close-up view of Ireland LIP:

As For Scandinavian peninsula, no LIPs were traced in the dataset.

[Fenerit]

Few screenshots of a world's area at different levels showings how will be the age's locations (calm, coffees and music, here).