Global Paleoshoreline data

Together with former Ph.D. student Logan Yeo, we’ve reverse-engineered a set of global paleoshoreline compilations by Golonka et al. (2006) [1] and Smith et al. (1994) [2] and taken them back from the age of “dark data” being only published in analogue form, to fully digital versions. The paleoshoreline models are made available publicly in different formats, ready to be reconstructed with GPlates using different plate models. The data is published on the web alongside the paper (in press) in the Australian Journal of Earth Sciences (Heine, Yeo & Muller: Evaluating global paleoshoreline models for the Cretaceous and Cenozoic, Aust. J. Earth Sciences, in press) and they show the evolution of land area over time from ~150 Ma to the present according to the two different paleoshoreline estimates.

The files are available on my GitHub page here in *.gpml, *.geojson and *.shp format and can be viewed online. Unfortunately it doesn’t seem to be possible to embed the map on wordpress.com – I originally envisaged some funky webX.X embedded mapping here, but no. Instead web1.0 style links to follow for a sneak peek and some screenshots below:

1. Golonka et al. (2006) models (examples):
   • 147.8 to 139.0 Ma geojson rendering
   • 139 to 123 Ma geojson rendering
   • 123 to 98 Ma geojson rendering
   • 98 to 83.8 Ma geojson rendering
   • 83.8 to 58.4 Ma geojson rendering
   • 58.4 to 48.5 Ma geojson rendering
2. Smith et al. (1994) models:
   • 16.0 to 11.6 Ma geojson rendering
   • 37.2 to 33.9 Ma geojson rendering

The rendering through GitHub is fast and allows a quick overview about the global and regional paleoshoreline locations, allowing zooming in and panning.

Paleoshorelines in the Golonka model for the 139-123 Ma time slice rendered from a geojson file live on GitHub. The colored area inside the polygon is equivalent to interpreted land (above sealevel) in the given time interval.

Another option to access the data is to use the version on CartoDB and interactively query and alter the data.

References:

[1] GOLONKA J., KROBICKI M., PAJAK J., VAN GIANG N. & ZUCHIEWICZ W. 2006. Global Plate Tectonics and Paleogeography of Southeast Asia. Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Arkadia, Krakow, Poland.

[2] SMITH A., SMITH D. G. & FURNELL B. M.1994. Atlas of Mesozoic and Cenozoic coastlines. Cambridge University Press, 112 p. Cambridge, United Kingdom.

Updated geological time scale color palettes

While it has been a little break over the summer on this blog, I have nevertheless been able to make a few updates related to the geological time color palettes (see this link for the original post). I have added the GTS2004 palettes (epochs and ages) and also the SEPM95 timescale. The color palettes (or *.cpt files) are designed for use with the Generic Mapping Tools (GMT) but can also be loaded in GPlates. On cpt-city, other formats are also available:

The gradients on cpt-city are usually available in each of the following file formats:

• Generic Mapping Tools, GMT (cpt)
• CSS3 gradients (c3g)
• GIMP (ggr)
• Gnuplot palette files (gpf)
• POV-Ray colour map headers (inc)
• PaintShop Pro’s native format (having the extension PspGradient), which can also be read by Photoshop (psp)
• The SAO format DS9 (sao)
• Scalar vector graphics gradients (svg)

Both palettes are still incomplete and require the extension back in geological time or adding eons or epochs. You can find the files on my BitBucket repository (https://bitbucket.org/chhei/gmt-cpts/). Any contribution to extend the individual files or add new timescales (or formats such as for QGIS) will be greatly appreciated!

Rift migration and asymmetric continental margins

Yesterday, our paper on rift migration and formation of asymmetric continental margins was published in Nature Communications. Using high resolution forward numerical models we investigate the influence of extension velocities on the evolution of continental rifts to passive margins. We find a strong correlation between margin width, asymmetry and extension velocity, illustrated by the conjugate South Atlantic passive margins. Our models can explain the highly asymmetric and hyperextended passive continental margins, further, we propose that large amounts of crustal material during the rift migration phase are transferred from one side of the rift to the other, challenging conventional ideas about passive margin formation. This means that large parts of the outer margins off West Africa could actually be composed of crustal material originating from the conjugate Brazilian margin.

(a–e) Fault kinematics of the model. Active faults are shown in red and inactive faults in black. Brittle faults are indicated with solid lines, ductile shear zones with dashed lines. The wide margin is formed through rift migration and sequentially active faulting towards the future ocean. Hence, thick undisturbed pre-salt sediments pre-dating break-up are predicted by our model to be deposited in the landward part of the margin (d,e). The final crustal structure of the model reproduces the strong asymmetry (f) of the conjugate Campos Basin–Angola margins (modified after ref. 5). Note that the geosection is drawn without vertical exaggeration at the same scale as the model (scale bar in the lower right corner is 50 km long). Vertical scale is in seconds two-way travel time (TWT). Source: Brune, Heine, Perez-Gussinye & Sobolev, Nature Communications (http://www.nature.com/ncomms/2014/140606/ncomms5014/full/ncomms5014.html), licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License (http://creativecommons.org/licenses/by-nc-nd/3.0/).

The GFZ Potsdam has also issued a press release related to this [in German].

Citation: Sascha Brune, Christian Heine, Marta Pérez-Gussinyé & Stephan V. Sobolev, 2014, “Rift migration explains continental margin asymmetry and crustal hyper-extension”, Nature Communications, 5, doi: 10.1038/ncomms5014. The paper is openly accessible, licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

Update 1 (2014-06-11):

Nature Comms’ Article metrics are a pretty cool indicator for immediate online impact (and I believe future citations). By now a few of the standard science news outlets have picked up the press releases (changing by the minute. Here’s a static (and human) collection of the news around the article (including some of the Altmetric links):

• CienciaPlus.es: La separación de América del Sur y África creó márgenes asimétricos
• ScienceDaily
• BeforeItsNews:
• EurekaAlert: Asymmetric continental margins and the slow birth of an ocean