escort {GCDkit} | R Documentation |
This is an implementation of the ESCORT expert system (Pearce 1987) aiming to identify the geodynamic setting of an igneous rock. The system takes into account specialist knowledge on the geological setting, mineralogy, petrology and whole-rock geochemistry, the latter based on compilation of a large body of high-quality data from known geotectonic settings.
escort(elconc, geolobs, geolmb, minobs, petobs) escortHtmlOutput(mat, title = "escoRt results") .escortTcl()
elconc |
Elemental concentrations |
geolobs |
Geological observations |
geolmb |
Corresponding measures of belief (0-1), 1 = maximal confidence |
minobs |
Mineral observations |
petobs |
Petrologic observations |
mat |
The output of the main |
title |
Title of the html window with the output |
This expert system assigns an lava of unknown affinity to its most probable tectonic setting of eruption on the basis of the following parameters:
1. The content of one or more of the immobile elements:
Ti, Zr, Y, Nb, P and Cr
2. The geological environment of the lava sequence:
Terrestrial, Shoreline, Shelf, Reef, Turbidite, Pelagic, Pillowed Flows, Sheet Flows, Non-sheet Flows, Pyroclastics, Sheeted Dykes, Sediments, Cryst. Basement, Int-acid Pluton, Basic Pluton, Other Volcanic, Thrust
3. The phenocrysts present in the lavas:
Plagioclase, Clinopyroxene, Olivine, Orthopyroxene, Amphibole, Mica, Quartz, Feldspathoid, K-feldspar
4. The petrological characteristics of the lavas:
Fe enrichment/the lack thereof
Possible geotectonic settings recognized by Escort:
Abbrev. | Description |
N-OR | Mature oceanic spreading centre of "normal" bathymetry not associated with subduction |
P-OR | Oceanic spreading centre showing bathymetric evidence of plume influence |
I-OR | Incipient spreading centre < 500 km from a continental margin |
B-OR | Spreading centre in a back-arc or inter-arc setting |
F-OR | Spreading centre forming fore-arc basin crust, either by fore-arc |
spreading or spreading prior to arc development | |
O-VA | Volcanic arc developed on oceanic lithosphere |
C-VA | Volcanic arc developed on continental lithosphere |
CZ | Post-collision settings, including post-collision rift terranes |
O-WP | Intraplate volcanism on oceanic lithosphere |
C-WP | Intraplate volcanism on continental lithosphere excluding strongly attenuated terranes (beta values >3) |
N-CF | Continental flood basalt terrains and zones of strong attenuation not subduction-related |
B-CF | Continental flood basalt terrains and zones of strong attenuation associated with subduction |
Abbrev. | Examples |
N-OR | Mid-Atlantic Ridge (63); East-Pacific Rise (20); Costa-Rica Rift (48); Carlsberg R. (6); |
Galapagos Rise (39); Pacific-Antarctic Ridge (56) | |
P-OR | Iceland area (86); Azores area (60); Tristan area (35); Bouvet area (50) |
I-OR | Atlantic margin (36); Red Sea/Gulf of Aden (5); Gulf of California (24) |
B-OR | Shikoku Basin (40); Scotia Sea (20); Tyrrhenian Sea (2) |
F-OR | No extant examples; O-VA data base used. |
O-VA | New Britain (163); Izu-Marianas (27); L. Antilles (127); N. Ireland(59); S. Sandwich Is.(10); |
Tonga-Kermadec (10); Singihe-Halmahera (23) | |
C-VA | Andes (48); Cascades (7); Aegean (20); C. America (23); Aeolian arc (31); Sunda arc (43) |
CZ | Papua-New Guinea (98); Alps (43); China (2); Italy (33) |
O-WP | Hawaii-Emperor seamounts (111); other Pacific Is. (44); Indian Ocean/Red Sea Is. (59); |
Atlantic Is. (150) | |
C-WP | African Rift (185); Libya/Sudan (30); Cameroon Line (140); Europe (31); S. New Zealand (21); |
Australia (26) | |
N-CF | British Tertiary Province (28); E. Greenland (33); Morocco (17); Parana (53); Deccan (24); |
Arabia/Afar (46) | |
B-CF | Patagonia (44); Bransfield St. (21); N. Zealand (63); Manchuria (45) |
The escort
function returns a list results
with the following items:
Geotectonic Setting |
a list of possible geotectonic settings, with corresponding probabilities and final decision regarding the likely and unlikely settings. |
Magma Type |
a list of possible magma environments (OR, VA, CZ, WP, CF), with corresponding probabilities and final decision. |
Rock Type |
a list of possible rock types (basic, intermediate, evolved), with corresponding probabilities and final decision. |
The final decision of the EscoRt expert system is displayed by a series of symbols where:
*** = Likely Setting
** = Probable Setting
* = Possible Setting
ooo = Unlikely Setting
escortHtmlOutput
is a utility function showing the result in the HTML format (in a web browser).
Julian Pearce, PearceJA@cardiff.ac.uk
R version: Vojtech Janousek, vojtech.janousek@geology.cz
Pearce JA (1987) An expert system for the tectonic characterization of ancient volcanic rocks. J Volcanol Geotherm Res 32:51-65 doi:10.1016/0377-0273(87)90036-9
# Loading some arbitrary data to get the plugin sourced sampleDataset("sazava") Parent<-"User-defined analysis" # Lorne lava as an example (Pearce 1987) # Concentrations elconc<-c(1.27,198,20.8,14.3,0.36,260) names(elconc)<-c("TiO2","Zr","Y","Nb","P2O5","Cr") # Geological constraints geolobs<-c("Terrestrial","Non-sheet Flows","Cryst. Basement") geolmb<-c(0.95,0.95,0.95) # Measures of belief (0-1), 1 = maximal confidence names(geolmb)<-geolobs # Petrologic constraints petobs<-"No Fe enricht." petmb<-1 names(petmb)<-petobs # Mineralogic constraints: minobs<-c("Clinopyroxene","Olivine") minmb<-c(1,1) names(minmb)<-minobs results<-escort(elconc=elconc,geolobs=geolobs,geolmb=geolmb,minobs=minobs,petobs=petobs) print(results) # HTML formatted result escortHtmlOutput(results) # Calling the GUI allowing to select a sample from the current dataset sampleDataset("atacazo") .escortTcl()