Tag: geology

Geologic Figures Database, step 1

I hope to someday put together a tagged database of figures pulled from the geological literature that may be useful to others, primarily maps and stratigraphic columns.  For now, though, I am sharing an Evernote notebook to which I will be adding over time.  It can be accessed here:

https://www.evernote.com/pub/matthewbk/publicimages [EDIT: No longer. 2014-02-04]

Future plans include tagging the images (type of map, area covered, stratigraphic units) but I am not sure of the platform to use.  Tumblr, Blogger, or even Pinterest (in addition to the possibility of Drupal) are all possibilities at this point that will allow collaboration.

Comps prep: visualizing tectonic plate interactions

Since I don’t have a blank map handy, I was playing around with a different way to visualize tectonic plate interactions so I can remember them more easily.  This sketch shows which plates touch other plates, but doesn’t go so far as to describe the direction of movement or the type of each boundary.  

 

Under this model (which is all sixteen of the plates shown in the textbook I’m using), there are 34 specific plate-plate interactions.  Luckily I don’t have to explicitly remember them as a list: just knowing what a few plates are doing makes it pretty simple to hypothesize the movement of everything else (in theory, at least).

Proof of Concept – Paleogeographic Maps and _Diplodon_

This figure has taken me a good deal of time to make. Not really in the actual production, but it’s been a long time gestating since conception.

Dissertation - 220Ma for arrow maps 2012-06-21

The genus Diplodon, as determined by the specimens to which that name has been applied, has been around since the Middle to Late Triassic. In the dissertation dataset, this works out to the 220 Ma time slice, or the Carnian stage. This is a map of what the world may have looked like at about that time period*.

Why is this important? In general, it’s important because it shows the geographical relationship among these occurrences as it may have been when these organisms were alive. Many paleogeography or historical biogeography papers ignore what the past geographic relationships may have been and focus on mapping a paleolandscape or biogeographic distribution onto a modern map.

Consider the possibility that these occurrences are not the earliest record of this genus (you would be right). If you were looking for additional material with only these four occurrences on which to base your search, you would look geographically nearby. Looking at a modern map would limit you to southern and eastern North America, but as you can see from the figure here, the paleogeography could support a South American or even African population. (I’ll tell you later why this this probably won’t work out.)

For the dissertation, this map is important because it (and others like it) can help show how far this genus is about to spread, and how long this is going to take. You may remember that I’m more interested in names than evolutionary relationships, so I hope to answer the question: how much time and space does there need to be between occurrences before we throw up our hands and say “this genus can’t possibly have survived that long?” The map series will help define where (and where not) there was a chance for lineage continuity.

*The background map, an achievement in itself that I take no credit for, is a product of Ron Blakey and Colorado Plateau Geosystems Inc. The positions of the continents are supported by Chris Scotese’s plate tectonic reconstructions as part of the Earth System History GIS collection. The positions of the Diplodon occurrences were mathematically rotated to these positions using the PointTracker software, also from Scotese.

Some translation help for the Brazil 1:1,000,000 geology map from CPRM

This is not complete, but hopefully helps out other English-but-not-Portuguese speakers like myself.

Here are translations (as best as I can figure them out) of the headers in the attribute table for the Brazil 1:1,000,000 geology map.
SIGLA_UNID = unit code
COD_UNI_ES = ?
SIGLAS_ANT = acronym something
NOME_UNIDA = unit name
HIERARQUIA = unit type (formation, lithofacies, unit, etc.)
IDADE_MAX = maximum age (years)
ERRO_MAX = assuming the plus/minus on IDADE_MAX
EON_IDADE_M = eon (Proterozoic, Phanerozoic, etc.)
ERA_MAXIMA = maximum possible era
PERIODO_MA = maximum possible period
EPOCA_MAX = maximum possible epoch
SISTEMA_GE = maybe what defines the type of unit it is? things like paleontology, structure, isotope, etc.
METODO_GEO = ?
QLDE_INFER = something about direct versus inferred measurements
IDADE_MIN = minimum age (years)
ERRO_MIN = assuming the plus/minus on IDADE_MAX (years)
EON_IDADE_1 = eon (not sure how this differs from EON_IDADE_M)
ERA_MINIMA = minimum possible era
PERIODO_MI = minimum possible period
EPOCA_MIN = minimum possible epoch
SISTEMA_1 = see SISTEMA_GE
METODO_G_1 = see METODO_GEO
QLDE_INF_1 = see QLDE_INFER
AMBSEDIMEN = first-order environment, so “continental,” “marine,” “transitional,” etc. values (“ambiente” is environment)
SISTSEDIME = second-order environment, so “deep,” “siliciclastic platform,” “fluvial,” etc. values
TIPO_DEPOS = third-order environment, so “pelagic,” “delta plain,” etc. values
ASSOC_MAGM = maybe magma source type?
NIVEL_CRUS = crustal level?
TEXTURA_IG = igneous texture
FONTE_MAGM = magma source
MORFOLOGIA = igneous morphology (like “batholith”)
AMBIENTE_T = tectonic environment
METAMORFIS = metamorphic type
METODO_G_2 = see METODO_G
TEMP_PICO = peak temperature
ERRO_TEMP_ = plus/minus on TEMP_PICO
PRESSAO_PL = pressure something
ERROR_PRESS = plus/minus on PRESSAO_PL
TIPO_BARIC = how something was determined
TRAJETORIA = how something was determined
AMBIENTE_1 = ?
LITOTIPO1 = lithotype
LITOTIPO2 = secondary lithotype
CLASSE_ROC = igneous, sedimentary, or metamorphic
CLASSE_R_1 = see CLASSE_ROC, with less values filled in
BB_SUBCLAS = subclass of CLASSE_ROC
BB_SUBCL_1 = subclass of CLASSE_R_1, I think
OBJECTID = the object ID
IDADE_MA_1 = see IDADE_MAX (all NULL)
ERRO_MAX_1 = see ERRO_MAX (all NULL)
EON_ID_MAX = maximum possible eon (EON_IDADE_M?)
PERIOD_MAX = see PERIODO_MA?
MET_ID_MAX = looks like method of determining maximum age
MET_DAT_MA = looks like the details of MET_ID_MAX, like what type of dating was used
QLD_ID_MAX = (quality?) whether the maximum age was determined with direct or indirect methods
IDADE_MI_1 = see IDADE_MIN
ERRO_MIN_1 = see ERRO_MIN
EON_ID_MIN = maximum possible eon (EON_IDADE_M?)
MET_ID_MIN = looks like method of determining minimum age
MET_DAT_MI = looks like details of MET_ID_MIN, like what type of dating was used
QLD_ID_MIN = (quality?) whether the minimum age was determined with direct or indirect methods
AMBSED = see AMBSEDIMEN
SISTSED = see SISTSEDIME
TIPO_DEP = see TIPO_DEPOS
TEXT_IGNEA = see TEXTURA_IG
AMB_TECTO = see AMBIENTE_T
METAMORF = see METAMORFIS
TRAJET_PT = see TRAJETORIA
CLASSE_RX1 = see CLASSE_ROC
CLASSE_RX2 = see CLASSE_RX1
SUBCLA_RX1 = see BB_SUBCLAS (of CLASSE_RX1)
SUBCLA_RX2 = see BB_SUBCL_1 (of CLASSE_RX2)
Shape_Leng = length of polygon (circumference?)
Shape_Area = area of polygon

Wanted (and some found): Geologic maps (formation contacts) of South America countries, for use in GIS

Here’s a good ol’ plea for help from the scientific community. As my questions to “the scientific community” via Academia.edu have gone unnoticed, I’m posting this out here to see if anyone else searching for the same thing has had any luck. I’m building a GIS (geographic information system) model to determine the possible biogeographic districbution of a genus through time. What I need for this, since the fossils are from South America, is a good geologic map, either of most of the continent or of the countries of Brazil, Argentina, Ecuador, and Peru. Hunting around online hasn’t shown me anything that I want to shell out a bunch of money for, site unseen, and I’m honestly trying to avoid having to scan paper maps and register them (additionally, I haven’t been able to access our worldwide collection of paper geologic maps recently). 1:500,000 or 1:100,000 would be great, but I’d even take 1:1,000,000 at this point. I need something with formational contacts so I can plot possible distributions. So that’s the challenge of the day: have any geologists in South America discovered a good source for this type of material? Would you be willing to share or trade? Drop me an email at one of the addresses on the right sidebar if you can help.

Brazil

UPDATE 2011-08-15: I found (finally) an online version of the Geological Map of Brazil at 1:1,000,000 scale. Unfortunately it is only available in a viewer, broken up into small sections. Anyone know where I can download the full dataset, or at least that data for those sections? UPDATE 2011-08-15 1431: Thanks to Sidney Goveia over at Geosaber, I tracked down the Brazil data to Geobank, so here goes nothing! If you are using a Mac, make sure you extract the contents of the ZIP files using StuffIt Expander (if you have it) rather than Archive Utility, otherwise you don’t end up with a folder.

Peru

UPDATE 2011-08-16: You can download a formation-level geological map of Peru at the 1:1,000,000 scale from INGEMMET – the Instituto Geologico Minero Y Metalurgico. There are a few steps through the online viewer (note: this is the new viewer, so the following steps may not work the same), which may appear in Spanish at first but for some reason decided to reload partway through in English. If you want, you can try to figure out how to turn on the layer under the Map–>Geodatabase menu, but really when that menu comes up you want to click the Download/Descargas folder icon, then select the Geologia layer (SHP icon next to it). It also looks like you can download the data as a KML file for Google Earth. A structural layer (Dominios Estructurales) also looks available, and I checked out the radiometric date layer (Dataciones Radiometricas) as well, which could be useful. You might need to check the projection on the geologic map once you download it. I imported it to QGIS at first and it came up as WGS 84 (probably because of the existing project), but I dug around and figured out that it works as PSAD_1956_UTM_Zone_18S. Need a map key for formation symbols? You can download scans of the paper version of this map from here, one of which has the legend. If the correct map doesn’t come up at that link, click on “Ministerio de Energia y Minas. Instituto de Geologia y Mineria” so see the others. The symbology is different. An alternative large-scale (1:100,000) but low-quality set of maps is available here but will not easily go into GIS.

Confusing Words #1 – Carbonaceous

Some geology words just add confusion to the reader.

Confusing word:
Carbonaceous – Relating to the organic or carbon content of the rock. Example: “This siltstone is really carbonaceous!” when referring to an organic-rich siltstone.

Could be confused with:
Carbonate or derivative – Being made up of a carbonate compound (usually calcium carbonate). Example: “The carbonate shale was very thick” when referring to a mix of clay and limestone minerals.

Since “Carbonate” is a word many geologists learn much earlier than “Carbonaceous”, I think the latter should fall out of use. “Organic-rich” is a much more descriptive term.