Sand distribution along shelf-edge deltaic systems : a case study from eastern offshore Trinidad

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dc.contributor.advisor Moscardelli , Lorena Gina , 1977 -
dc.contributor.advisor Wood , Lesli J .
dc.contributor.committeeMember Fisher , William
dc.contributor.committeeMember Steel , Ronald
dc.creator Davila -Chacon , Anmar Carolina
dc.date.accessioned 2011 -02 -15T21 :11 :17Z
dc.date.accessioned 2011 -02 -15T21 :12 :53Z
dc.date.accessioned 2014 -02 -19T22 :55 :57Z
dc.date.available 2011 -02 -15T21 :11 :17Z
dc.date.available 2011 -02 -15T21 :12 :53Z
dc.date.available 2014 -02 -19T22 :55 :57Z
dc.date.created 2010 -12
dc.date.issued 2011 -02 -15
dc.date.submitted December 2010
dc.identifier.uri http : / /hdl .handle .net /2152 /ETD -UT -2010 -12 -2255
dc.description.abstract The study area is situated along the obliquely converging boundary of the Caribbean and South American plates offshore eastern offshore Trinidad . Major structural elements in the shelf break and deep -water slope regions include normal and counter -normal faults to the south and large transpressional fault zones to the north . Well logs and biostratigraphic information were analyzed for twenty -four wells in the study area to refine previous depositional environment interpretations . For purposes of this net sand distribution analysis it was decided to consider the deltaic portion of the shelf transit cycle , against the marine portion of the shelf transit cycle and were named T and R cycles , respectively . T and R cycles were interpreted based on well log patterns and depositional facies shifts . Six T /R cycles were interpreted within the Pliocene to recent stratigraphic succession and shelf edge trajectories were also mapped for each of these cycles based on earlier stratigraphic correlations . Net -to -gross (NTG ) ratios were calculated for each component of the T /R cycles and plotted against total thicknesses and net sand values . In addition , NTG trends were mapped for each interval and analyzed based on their proximity to the corresponding shelf edge . Mapping of the shelf edge trajectories (SET ) revealed that (1 ) SET migrate northeasterly across the Columbus Basin through time and (2 ) shelf edge orientations are parallel to the strike of growth faults in the south but deflect to the northeast near the Darien Ridge indicating a strong underlying structural control . The NTG plots and maps also revealed that (1 ) For T cycles , NTG values never exceed 60 % and are inversely proportional to total thickness , (2 ) For R cycles , NTG values are highly variably ranging from 35 % to 90 % , (3 ) NTG values increase as the shelf break is approached and (4 ) The distribution of NTG ratios is also controlled by accommodation space created by local structures . The Guiana current is believed to play an important role in the redistribution and reworking of sand in the Columbus Basin . Aggradation and progradation distances were computed for each interval and the results suggest that the younger Sequences C2 (T -R cycle E ) and C3 (T -R cycle F ) show a stronger progradational trend than the older C4 , C5 and C6 . This strong progradational trend might indicate delivery of sand basinwards , while for the older intervals ; the aggradational trend suggests an increase in sediment storage . In long -term scale (1 -2 m .y . ) the Orinoco Delta seems to behave as an aggradational delta that increases sediment storage due to growth fault and high subsidence rates . However , in the short -term scale , the Orinoco delta seems to behave as a rapid progradational delta , for the younger sequences C2 and C3 , where sediment bypass is more likely to occur ; and as a rapid aggradational (slow prograding ) margin for the older intervals C4 , C5 and C6 .
dc.format.mimetype application /pdf
dc.language.iso eng
dc.subject Orinoco Delta
dc.subject Trinidad
dc.subject Shelf -edge
dc.subject Delta
dc.subject Net -to -gross
dc.subject Biostratigraphy
dc.subject Sequence stratigraphy
dc.subject Well logs
dc.title Sand distribution along shelf -edge deltaic systems : a case study from eastern offshore Trinidad
dc.description.department Geological Sciences
dc.type.genre thesis *
dc.type.material text *
thesis.degree.name Master of Science in Geological Sciences
thesis.degree.level Masters
thesis.degree.discipline Geological Sciences
thesis.degree.grantor University of Texas at Austin
thesis.degree.department Geological Sciences
dc.date.updated 2011 -02 -15T21 :12 :54Z

Citation

Sand distribution along shelf-edge deltaic systems : a case study from eastern offshore Trinidad. Master's thesis, University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2010 -12 -2255 .

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