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Home My WebLink AboutGMC Data Report No. 049u.S.S.R. , · Narlon' , .'.;' 'Anchora \ ' Gulf of Alaska 0 200 400 600 km LOCATION OF TENNECO MIDDLETON ISLAND January 25, !984 were recovered and utilized in graphic analysis of the-well "Taxa stratigraphically out of place through caving and reworking were?eason-' ably common; .Caved material .was primarily of Miocene age while~i'F~'~worked ...'.taxa were mostly Cretaceous. Elimination of these taxa and?~graphic ]~:~.'~.analysis of the remainder produced the following relative age determina- .,. D. J. VerSteeg 1094 AB ATTN' J. I. Maynard PALYNOLOGICAL'ANALYSIS OF TENNECO . MIDDLETON ISLAND ~1- 59°24'33.15"N ". 146°15"37.59'W - . ..-~.... -...]].~]...?~}¢?~~~?..~" ....... ~"~ ......... ~' GULF OF ALAS~ I have completed study of 130 palynology preparatSons:'fro~.,thO~i~nheco'-': ~iddleton I~land ~1 ~ell. [xclus~vely of ditch cuttin~S,_:'-:these'~ampleS':: covered the interval from 240-12,002 feet. Palynomorph:?.~rec'oVery: was :~enerally ~ood ~n ~he ~eo~ene, ~radually deter~orat~n~..~th-.depth, until ~ood b~ostrati~raphic control ~as lost at about 9,100 feet;-fair control and reasonable recoveries continued to 1.~.. Palynolo~ical data from 12~ additional slides (prepared' in 1975} was "also integrated into the study. .' · .'.~'.; . "-: ' ,'-" ~ '-. v · '~": .'"' Eighty-nine taxa.(pollen and spores, dinoflagellates and .fungal SPores) 460' Top of Pliocene ('proJected) 2,275' Top of Upper Miocene 3,620' .Top of Middle Miocene 4,960' Top of Lower Miocene 5,630' Top of Upper Oligocene 6,810' Top of Lower Oligocene 9,000' Top of Upper Eocene 9,670' ;Top of Middle Eocene 10,340' Top of Lower Eocene 10,880' Top of Paleocene? Since correlation of the lower Paleogene in this well is by a projec- tion of the line of correlation, the possibility exists that T.D. was in sediments of Lower Eocene rather than Paleocene 'age. No significant unconformities were detected in the well, although a "weathered" zone around 9,300 feet may represent a brief nonmarine erosional episode. This may correlate with the TE3 regressional se- quence of Hardenbol and Berggren (1977). Visual kerogen thermal maturation levels were pregeneration or early generation to about 6,900 feet and early peak oil (early gas) at T.D. It appears that even deep in the well expulsion phase was never reached. Nearly all samples were of the mixed kerogen type, usually dominated, however, by micrite, wood, cuticle fragments and other structured elements (see attached sheets). These thermal maturation levels are in general agreement with our in-house vitrinite reflectance values (T.E. Hemler memo of 9/2/83). In general, the depositional environment of the Tenneco Middleton Island well was marine or marginal marine to T.D. with only brief episodes of nonmarine deposition/erosion. · · The first 16 samples, of Plio-P]eistocene age, are effectively barren. The first productive sample (1,680') is in marginal marine sediments of Lower Pliocene.age. Sediments become 'increasingly marine with depth and by 2,850 feet palynology samples show a rich and diverse dinoflagel- late flora. Coaly.particles from this..interval should 'probably~be considered detrital. -~'-~- ~ ~' ~, ; - "~'~·'-,~ ~i~.~.~?!~.~'" Samples from 3,355-3,880 feet suggest '.,a Ishallower, marginal ~ma~ih6 to brackish environment. .Fungal spores...suggest that intermittent swamps may have existed.' ...... "' ~ By 3,930 feet conditions had again becOme marginal marine and remained Reworked 'Cretaceous taxa are common in this interval. A brief nonmarine episode is suggested at around 5,460 feet, so to about 4,780 feet. in .~r~ 1. A -i~:f ~ )nmari although by 5,540 feet~-sediments are again marine. Similar;relatively . shallow water Conditions ·'continue to 8,750 feet at which point a brief brackish· or swampy.interval is suggested -~;" --- ' .... . , , ~, .'. '.'..: ,. ~::=- .. .. ~ .. At 8,920 feet Sediment'~;a~e]'.~gain marine and predominently continue so to T.D. Brief nonmarine'periods are suggested at 9,'380 feet,.where the organic material appears "weathered", and at 10,380 feet 'where the recovery of palynomorph~ i~ very sparse. Caved ~eo~ene taxa {primarily in s .. Miocene) are co~on thi ";:interval. .. ' the deepest ~ample {1~,002' 1.~.) still produced a lo,er lertiary a~e assemblage' of pollen, spores, fungals and dinoflagellates with no indication that the Mesozoic had been penetrated R. W. Baxendale RWB/df GRAPHIC CORRELATION OF TENNECO MIDDLE'i'ON ISLAND ~ 1 AGAINST THE ALASKA COMPOSITE STANDARD 4000' 5000' 6000' 7000' 9000' -- 13000' -- 14000' 15000' 16000' - I ?000' -- u.I Ltl UJ Z Z Z ua U.I U.J uJ Ud ua "'"'1~o ul l"'il~l I I 16000' - I i i I i i I I I I i . 20200 20400 20600 20800 2 l(xx) 21200 21400 21600 21800 22000 22200 22400 22600 COMPOSITE STANDARD UNITS