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*************BASIN ANALYSIS SYSTEM ************ George Hamilton, Consulting Geologist P.O Box 144, Sterling, Virginia 22170 Telephone:804 383 8093 ------------------------------------------------------------------------------ (c) Copyright 1988 Hamilton Exploration All rights reserved. Move down one page to begin. ----------------------------------------------------------------------------- ------------------------------------------------------------------------------ ..MENU I. Craton Interior Basins: \CRATON\. MODEL NO. 1. II. Continental Multicycle Basins: A. Craton Margin Composite: \IIAMARG\. MODEL NO. 2. B. Craton Accreted Margin Complex: \IIBCAMB\. MODEL NO. 3. C. Crustal Collision Zone---Convergent Plate Margin which includes Tethyan closed, trough and open types: \CCZM\. MODEL NO. 4. III. Continental Rifted Basins A. Craton and Accreted Zone Rift: \CAZR\. MODEL NO. 5. B. Rifted Convergent Margin which includes "Pacific" back arc, transform and median types: \RCM\. MODEL NO. 6. C. Rifted Passive Margin which includes "Atlantic" parallel and transform types: \RPM\. MODEL NO. 7. IV. Delta Basins, Tertiary to Recent: \DELTA2\. MODEL NO. 8. V. Forearc Basins: \FOREAC\. MODEL NO. 9. ..END(MENU) ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- ..CRATON Is there evidence that the prospective basin is located on continental rather than oceanic crust? IS THE BASIN LOCATED ON INTERIOR CONTINENTAL OR MOSTLY CONTINENTAL CRUST ? You are trying to determine the basin's position relative to the earth's major crustal zones, i.e. interior continental versus oceanic crust . yes\CON1\,no\OCE1\. ----------------------------------------------------------------------- ..CON1 Is there evidence of divergent past plate movement involved during the early cycle of basin formation rather than convergent plate movement . IS THE BASIN LOCATED IN AN AREA OF PRIMARILY DIVERGENT (EXTENSIONAL) CRUSTAL PLATE MOVEMENT IN AREAS OF PRECAMBRIAN ACCRETION WHICH REMAINED ESSENTIALLY STABLE DURING THE PHANEROZOIC ? You are trying to determine if the basin's position is on a divergent or extensional continental crust rather than a convergent or compressional continental crust . yes\DIVG\,no\CONV\. ..END(CON1) ----------------------------------------------------------------------- ..DIVG Is there evidence of a simple divergent basin rather than a basin that has been modified by later convergent plate movements ? IS YOUR BASIN A SIMPLE DIVERGENT BASIN AS OPPOSED TO ONE THAT HAS BEEN MODIFIED OVER GEOLOGIC TIME BY SUBSEQUENT CONVERGENT PLATE MOVEMENTS ? Having established that you have a divergent basin You are trying now to determine if it may have been modified later by convergent plate movements . yes\DIVG1\,no\DICON\. ..END(DIVG) ------------------------------------------------------------------------- ..DIVG1 Is there evidence of a cratonic interior basin ? DOES THE BASIN OCCUR IN THE INTERIOR OF A CONTINENTAL CRATONIC MASS RATHER THAN NEAR THE CRATON MARGINS ? You are trying to determine if the basin occurs entirely within the old cratonic interior near exposed Precambrian shield areas of a crustal plate, rather than near the margins of the craton . yes\CRA\,no\MARG\. ..END(DIVG1) -------------------------------------------------------------------------- ..MARG Is there evidence of a continental margin basin ? DO YOU HAVE A SIMPLE CRATONIC BASIN OF THE SAG TYPE LOCATED NEAR THE EDGE OF THE CRATON AS OPPOSED TO A BASIN ON A MARGINAL ACCRETED ZONE ? You are trying to distinguish between a fairly simple cratonic basin located near the craton margin rather than a more complex basin located along a younger accreted continental margin . yes\NEAR\,no\ACCRT\. ..END(MARG) --------------------------------------------------------------------- ..NEAR Is there evidence of a non-parallel, near-margin cratonic basin ? IS THE AXIS OF YOUR NEAR-MARGIN CRATONIC BASIN AT A SIGNIFICANT ANGLE TO THE MARGIN OF THE CRATON AS OPPOSED TO A BASIN WHOSE AXIS IS ESSENTIALLY PARALLEL TO THE MARGIN OF THE CRATON ? You are trying to distinquish between a simple cratonic sag basin located near the margins of the old craton and essentially at an angle to the craton edge, as opposed to a more complex craton marginal basin whose axis lies essentially parallel to the craton margin, and probably on a younger accreted margin . yes\CRA\ no\ACCRT\. ..END(NEAR) --------------------------------------------------------------------- ..CRA Is there evidence that the basement-profile of a basin is a simple sag rather than a rifted and fractured basement ? DOES THE BASIN OCCUR AS A FAIRLY SHALLOW SAG ON OR WITHIN THE CRATON WITH MINOR OR NO FAULTING ? You are trying to determine if the basin simply sags with minor or no faulting, as opposed to the basement of the basin being fractured with vertical horst and graben faulting and subsidence as the dominant features . yes\SAG1\no\RIFT1\. ..END(CRA) --------------------------------------------------------------------- ..RIFT1 Is there evidence of a simple cratonic interior basin developed in a fractured or rift zone ? IS THIS BASIN AN INTERIOR FRACTURED BASIN WITH VERTICAL HORST AND GRABEN FAULTING AND SUBSIDENCE AS THE DOMINANT BASIN FEATURES ? You are trying to determine whether this interior cratonic basin has a faulted or fractured basement rather than a simple sag basement with very little faulting . yes\IRIFT\ no\NONE\. ..END(RIFT1) --------------------------------------------------------------------- ..SAG1 ..window(SAG) 15,2,,,75,10 Conclusion: You have identified a favorable geologic setting for the occurrence of petroleum resources in a Craton Interior Basin. The following questions are intended to aid in evaluating your basin more fully . DOES THE CONTACT OF THE SEDIMENTS WITH THE BASEMENT IN THIS INTERIOR BASIN SHOW A SYMMETRICAL BASEMENT-PROFILE RATHER THAN AN ASYMMETRICAL BASEMENT PROFILE ? You are trying to determine whether the simple interior cratonic basin has a symmetrical basement profile as opposed to an asymmetrical basement profile . yes\SYM\ no\ASYM\. ..END(SAG1) -------------------------------------------------------------------- ..IRIFT ..window(IRIFT) 15,2,,,75,7 Conclusion: You have identified a favorable geologic setting for the occurrence of petroleum resources in a Craton Fractured Interior Basin. However, you may have a more complex basin of the craton-fractured-interior type which is better described as a Class IIB = \GOON\=\OUT\ or Class IIIA =\CAZR\ basin. Recommended that you check the descriptions for these two basin models. ..END(IRIFT) --------------------------------------------------------------------- ..SYM Is there evidence of a regular basement profile ? DOES THIS BASIN HAVE A FAIRLY REGULAR OR SMOOTH BASEMENT PROFILE WITH ONLY MINOR OR NO FAULTING ? You are trying to determine whether this basin has a regular basin profile, as opposed to an irregular profile due to faulting or rifting . yes\REG\ no\IRREG\. ..END(SYM) ----------------------------------------------------------------------- ..ASYM Is there evidence of a regular asymmetrical basin ? DOES THIS BASIN HAVE A FAIRLY REGULAR OR SMOOTH BASEMENT PROFILE WITH ONLY MINOR OR NO FAULTING ? You are trying to determine whether this basin has a regular basement profile, as opposed to an irregular profile due to faulting or rifting . yes\REGA\ no\IRRGA\. ..ASYM --------------------------------------------------------------------- ..IRREG ..window(IRREG)15,2,,,75,6 It would appear that you have a symmetrical cratonic basin with an irregular basement profile. This type of basin is more likely to be classified as a Class IIB basin \IIBCAMB\, (model 3) or a Class IIIA \CAZR\ basin. Recommend that you check these other basin models. ..END(IRREG) --------------------------------------------------------------------- ..REGA ..window(REGA)15,2,,,75,7 It would appear that you have a cratonic asymmetrically shaped basin with a regular basement profile. This type of basin is more likely to be classified as a \IIAMARG\ (model 2) or a\CCZM\(model 4) basin. There is also some possibility of it being a\DELTA2\(model 8) basin. Recommend that you check these other basin models. ..END(REGA) \MENU\. --------------------------------------------------------------------- ..IRRGA ..window(IRRGA) 15,2,,,75,7 It would appear that you have a cratonic asymmetrically shaped basin with an irregular basement profile. This type of basin is more likely to be classified as a\IIAMARG\, or\CCZM\, or Class IIIC \RPM\ basin. There is also some possibility of it being a Class IV \DELTA2\ basin. Recommend that you check these other basin models. ..END(IRRGA) --------------------------------------------------------------------- ..REG Is there evidence of a horizontal basin with no seaward tilting ? IS YOUR BASIN ESSENTIALLY HORIZONTAL OR LEVEL WITH NO SEAWARD TILTING ? You are trying to determine whether the basin has been fairly stable with no tilting due to subsidence or structural deformation . yes\LEVL\ no\TILT\. ..END(REG) --------------------------------------------------------------------- ..LEVL Is there evidence of a simple one-cycle (Paleozoic) cratonic basin ? DOES YOUR BASIN SHOW EVIDENCE OF ONLY A SINGLE CYCLE OR SEQUENCE OF DEPOSITIONAL OR TECTONIC EVENTS AND THE AGE OF SEDIMENTS ARE GENERALLY PALEOZOIC (LOCALLY UPPER PROTEROZOIC AND PALEOZOIC) ONLAPPING PRECAMBRIAN BASEMENT ? You are trying to establish whether your basin is a simple sag, one-cycle cratonic interior basin as opposed to a more complexly modified cratonic marginal basin with multiple depositional cycles or sequences . yes\ONE\ no\MULTI\. ..END(LEVL) --------------------------------------------------------------------- ..TILT Is there evidence of a tilted, marginal, multi-cycle, cratonic basin ? DOES YOUR BASIN SHOW EVIDENCE OF MORE THAN ONE CYCLE OR SEQUENCE OF DEPOSITIONAL AND TECTONIC EVENTS AND THE SEDIMENTS RANGE IN AGE FROM THE PALEOZOIC INTO THE MESOZOIC AND POSSIBLY EVEN INTO THE TERTIARY ? You are trying to determine if you have a basin, possibly located at or near the craton margin, that has been tilted seaward and has more than one depositional or tectonic cycle . yes\MULTI\,no\TYPEIV\. ..END(TILT) --------------------------------------------------------------------- ..ONE DO YOU THINK YOU HAVE A BASIN OF THE TYPE I CLASSIFICATION, A SIMPLE CRATON INTERIOR BASIN WITH A SINGLE CYCLE OF DEPOSITION OR TECTONIC HISTORY ? You are trying to determine whether you have a simple interior cratonic basin that has experienced a single depositional or tectonic type history. Analogs for this type of basin might be the Denver basin, Michigan basin, Illinois basin, or Williston basin . yes\TYPEI\,no\UNX\. ..END(ONE) --------------------------------------------------------------------- ..MULTI Is there evidence of a multi-cycle cratonic basin with possibly a delta depocenter of Tertiary age ? DO YOU THINK YOU HAVE A CRATONIC MARGINAL BASIN THAT HAS BEEN TILTED SEAWARD AND IN WHICH ADDITIONAL DEPOSITIONAL CYCLES HAVE TAKEN PLACE, POSSIBLY EVEN A DELTA DEPOCENTER OF TERTIARY AGE ? You are trying to determine if you have a cratonic basin, possibly located along a marginal sag or rift that has experienced more than one depositional and tectonic cycle and that could possibly have a delta depocenter of Tertiary age . yes\TYPEIV\,no\XTYPE\. ..END(MULTI) --------------------------------------------------------------------- ..TYPEI ..window(TYPEI)15,2,,,75,20 Conclusion: You have successfully classified a Class I Cratonic Interior Basin. DO YOU HAVE ONE OF THE FOLLOWING BASINS OR A SIMILAR BASIN: CINCINNATI ARCH, DENVER, FOXE, HUDSON BAY, ILLINOIS, JONES-LANCASTER, KNUD RASMUSSEN, LAKE SUPERIOR, SALINA-FOREST CITY, MICHIGAN, UNGAVA BAY, VICTORIA STRAIT, VOLTA, WILLISTON, WOLLASTON, LOWER, MIDDLE, AND UPPER AMAZON, CHACO, ORD, PARANA, PARNAIBA, SAO FRANCISCO, CHAD, ETOSHA, ILLIZI, KUFRA, MURZUK, OKAVANGO DELTA, TAOUDENNI, BARENTS WEST, GULF OF CARPENTARIA, DALY RIVER, GEORGINA, WISO, BALTIC, BARENTS EAST, MEZEN, MOSCOW, OLENEK, TUNGUSKA, DUFEK, MARIE BYRD, AND WILKES ? You are trying to determine if your basin is one of these specific basins or a basin, similar geologically to these basins, that has been classified Class I basin. yes\CRAI\,no\HALF\. ..END(TYPEI) --------------------------------------------------------------------- ..CRAI ..window(CRAI) 15,2,,,75,7 Conclusion: You have identified your basin as a Class I Continental Interior basin. You may have also selected one of the basins from the list of analog basins that have been classified as Class I basins. You are ready to make a detailed analysis of your basin. \MENU\. ..END(CRAI) --------------------------------------------------------------------- ..HALF ..window(HALF) 15,2,,,75,10 Partial success in describing a Class I basin . You have identified your basin as a Class I basin. You may be missing some crucial geologic information on your basin. Try reevaluating your information. You may have a basin that is better classified as a\IIAMARG\ Craton margin \IIBCAMB\ Craton Accreted Margin Complex or \CAZR\ Accreted Rift basin. ..END(HALF) --------------------------------------------------------------------- ..TYPEIV DO YOU THINK YOU HAVE A BASIN THAT HAS A DELTA DEPOCENTER OF POSSIBLY TERTIARY AGE ? If you have a multi-cycle craton margin basin that has a delta depocenter of Tertiary age. You probably have a \DELTA2\ basin. If it is not a deltaic basin then you probably have a more complex basin of a different type. yes\DELTA\,no\XTYPE\. ..END(TYPEIV) --------------------------------------------------------------------- ..DELTA ..window(DELTA) 15,2,,,75,7 Conclusion: You have identified a favorable geologic setting for petroleum potential and have a basin that is a cratonic basin, probably a cratonic margin basin, that has been the site for the later development of a delta depo- center. This is one form of a Type\IV\Delta Basin, possibly a Mackenzie or Niger type basin. ..END(DELTA) --------------------------------------------------------------------- ..XTYPE Possible evidence of multicycle basins other than craton or cratonic delta depocenters . If you have a multicycle basin that does not meet the criteria for the Craton Class I =\TYPEI\ basin or the Delta ClassIV basin,\IV\ that would be classified as one of the other basin models such as Class\IIA\or Class IIB =\GOON\=\OUT\. ..END(XTYPE) --------------------------------------------------------------------- ..NONE Favorable assumption of an interior sag basin rather than a rifted interior basin . Insufficient evidence at present that indicates whether an interior craton basin may have a basement that is classified as an interior rift or fracture basin . WOULD YOU LIKE TO ASSUME THAT YOU HAVE AN INTERIOR SAG BASIN RATHER THAN A RIFTED INTERIOR BASIN ? If you wish to assume that it is a simple interior sag basin then we can continue with the analysis of your basin . yes\SAG\,no\WHAT\. ..END(NONE) --------------------------------------------------------------------- ..WHAT Favorable assumption of a rifted interior basin . WOULD YOU LIKE TO ASSUME THAT YOU HAVE AN INTERIOR RIFTED BASIN ? If you wish to assume that it is an interior rifted basin then we can continue with recommendations for describing this basin class . yes\IRIFT\,no\UNX\. ..END(WHAT) --------------------------------------------------------------------- ..UNX Insufficient evidence at present that would indicate a simple interior cratonic sag basin of the Class I=\TYPEI\. You may wish to run through the other basin classes for classification or you may want to start with basin Class IIB or Class IIIA . \MENU\,IIBCAMB\,\CAZR\. ..END(UNX) --------------------------------------------------------------------- ..ACCRT Is there evidence that basin is located on accreted crustal zones near old craton margins and not on an old craton . IS YOUR BASIN LOCATED ON ACCRETED CRUSTAL ZONES NEAR THE MARGINS OF AN OLD CRATON, AND NOT ON AN OLD CRATON ? If your basin is not located within the interior or near-margin of a craton, then it must be located on some form of accreted crustal zone, as opposed to being located on oceanic crust . yes\XMODEL\,no\OCE\. ..END(ACCRT) --------------------------------------------------------------------- ..XMODEL Is there evidence that basin is described as a noncratonic or accreted zone basin ? Your basin is a non-cratonic or accreted zone basin and is described for other basin models, probably \IIAMARG\ and \CAZR\,\RCM\. ..END(XMODEL) --------------------------------------------------------------------- ..OCE1 ..window(OCE) 15,2,,,75,4 Your basin is an oceanic basin located on oceanic crust or partially on oceanic crust. You should check the\DELTA2\, and\FOREAC\basin model. ..END(OCE1) ---------------------------------------------------------------------- ..DICON Is there evidence that the basin was originally located on a divergent plate, and modified later by convergent movements either within or near the original basin location ? DO YOU HAVE A BASIN THAT WAS LOCATED ON A DIVERGENT CRATON PLATE THAT HAS BEEN TECTONICALLY MODIFIED BY LATER CONVERGENT PLATE MOVEMENTS ? You are trying to determine if you have a basin that originally would be classified as a divergent basin but has subsequently been modified by younger convergent type plate movements . yes\XMODEL\,no\MARG\. ..END(DICON) --------------------------------------------------------------------- ..CONV There is evidence that your basin is located on the margins or nearby interiors of two or more plates converging toward one another. Check basin\CCZM\and\RCM\. ..END(CONV) --------------------------------------------------------------------- End of first part Hamilton Exploration Basin Analysis System. For more information contact: G.H. Hamilton Consulting Geologist Grove Studios, Adie Road Hammersmith, London W6 0PW England ..END(CRATON)