Report on Foraminifera from 95 outcrop samples from 10 measured sections in the Gulf of Alaska Tertiary Province and 1 section in the Kodiak Tertiary Province.

For Convenience I have grouped the samples into 4 groups, partly in accordance with the stratigraphic correlation chart sent with the samples, and partly in consideration of the similarity of assemblages and nature of preservation. These groups are:

Pleistocene-Pliocene: Middleton Island, Tugidak Island

Pliocene-Miocene: Chaix Hills, Samover Hills, La Perouse Glacier

Miocene-Oligocene: Kulthieth Mtn., Suckling Hills, Icy Point, Yakataga Reef

Oligocene: Kayak Island, Miller Hills

Preservation is by far the best in the Middleton and Tugidak Island sections. Most specimens are fresh-appearing and free of adhering matrix; their chambers are empty; the pores are unaffected by solution or recrystallization; and there is no evidence of crushing and deformation such as is so prevalent in the older sections.

Certain species are more susceptible to deformation than others. The elphidiids and rotaliids seem little affected, while specimens of Globobulimina, Florilus, Pseudononion, Nonionella, and Virgulina can be totally flattened or squashed sideways and still retain their sutures and lobes so as to be recognizable. The various agglutinated forms, especially Haplophragmoides, also show a high degree of deformation.

Because of the poorer preservation in the older samples, many of my identifications are questionable, and I have left out a good many species as undeterminable on the basis of the present material.

The variation in size among the specimens of certain species, particularly Elphidium clavatum and Cassidulina tortuosa, is extreme (as much as 4- or 5-fold). I believe this is a result of the different ecologic conditions under which the species lived. Change in size of globigerinids is also striking. The specimens of Globigerina pachyderma in the Pleistocene sections are of normal size for that species (which is a small species for the genus). But in the older sections specimens of G. pachyderma are smaller than normal. And in the Miocene and Oligocene sections the other globigerinid specimens are notably smaller than normal-sized specimens of their respective species.

During study of specimens of Florilus labradoricus in this material it appears that specimens that in the past have been placed in different genera (Florilus, Pseudononion, and Nonionella) may be, in fact, only morphologic stages of a single genus, Nonionellina, as has been described by Voloshinova (1958, Mikrofauna SSSR, Sbornik 9, VNIGRI, Trudy, no. 115). Thus Florilus labradoricus (planispiral), Psuedononion auricula (trochospiral), and Nonionella miocenica (trochospiral with prominent lobe on one side) may actually belong to a single species, Nonionellina labradorica. However, for the purpose of signifying clearly which of these three forms (planispiral, trochospiral, or trochospiral with prominent lobe on one side) occurs in the various samples, I have used the three older conventional names. Actually, the Florilus-form only occurs in the Pleistocene where it is fairly abundant. Only the Florilus-form (commonly) and the Nonionella-form (less commonly) occur in the Pliocene, and both occur very rarely in the Oligocene. All three forms occur in the Miocene sections, but also very rarely.

The same kind of relationship may exist between species I have identified as Epistominella pacifica and Alabamina aff. wilcoxensis, the former having evolved from the latter which is predominant in one of the Oligocene samples.

For most of the samples I have indicated, by the letter D in the check lists, the one or several species that dominate the assemblage. But where the assemblage is meager, dominance does not seem significant.

Speaking in general, the Pleistocene-Pliocene sections are characterized by undeformed specimens and by dominance of Elphidium clavatum and the two large species of Cassidulina, C. californica with rounded periphery and C. tortuosa with angled periphery. Other frequent species, dominating in some samples, are Buccella frigida, Glandulina laevigata, and Uvigerina yabei. The only planktonic species noted in these youngest sections was Globigerina pachyderma.

In the Pliocene-Miocene sections, the two chief dominating species are Elphidium clavatum and Cassidulina tortuosa. Other frequent species, dominating in some samples, are Buccella frigida, Elphidiella oregonensis, Epistominella pacifica, Florilus labradoricus, and Nonionella miocenica. In these sections the planktonics are more diversified although G. pachyderma is still the major one.

In the Miocene-Oligocene sections, the dominating species are still Cassidulina tortuosa and Elphidium clavatum with the addition of Haplophragmoides aff. columbiensis. Other frequent species, dominating in some samples, are Cibicides lobatulus, Globobulimina auriculata, and Uvigerina yabei. In addition there are less common occurrences of the following species that comprise dominant elements in certain samples: Cassidulina californica, Cyclammina constrictimargo, Gyroidina condoni, Haplophragmoides obliquicameratus, Martinottiella nodulosa, Melonis affinis

In the Oligocene sections, faunal dominance is entirely different from that in the younger sections. The genus Elphidium is not present at all and Cassidulina is represented only by rare specimens of a small species. The agglutinated genera, Haplophragmoides, Gaudryina, and Cyclammina, are rather consistently present and make up the dominant elements in several of the samples. In addition, the following species, although not present throughout the sections, dominate in several samples: Alabamina aff. wilcoxensis, Cibicides pseudoungerianus, Virgulina aff. recta

Middleton Island section:

Forty species were identified in the 16 samples of this section. The fauna is quite consistent; no striking faunal differences are obvious from the top to the bottom, but there is a change in type of preservation between 63APr 27 and 29. Two of the 3 samples that are not from the measured section (63APr 85A and 85C) are more like the upper part of the measured section. In the third one (63APr 85H) the specimens are crushed and stained, suggesting it belongs with the lower part of the measured section.

The only species found here that has not been reported also in Recent sediments is Uvigerina yabei, which was described from the Pliocene of Japan. Asano (1950, Illustrated Catalogue of Japanese Tertiary Smaller Foraminifera, pt. 2: Buliminidae, p. 18, figs. 85-87) states that Uvigerina cushmani (which was described from off California) may be a variant of it and I would agree with this suggestion. However, the Middleton Island specimens are not like this Recent variant but are quite like the typical specimens of U. yabei. They also seem identical with specimens from Amchitka Island in the Aleutians from beds interpreted as of “Pleistocene or Pliocene age, probably the latter.” (Cushman and Todd, 1947, Contr. Cushman Lab. Foram. Res., vol. 23, pt. 3, p. 60, 66, pl. 16, figs. 4, 5). A number of other species in the Middleton Island section are identical with those from this Amchitka Island occurrence. Because of the long-ranging characteristic of species of Uvigerina, I doubt that Uvigerina yabei can be used to pin down precisely the age of the Middleton Island section. I would guess it to be either Pliocene or Pleistocene.

The check list shows a fluctuation in species dominance, and it seems likely that this fluctuation is a result of fluctuation in ecology (chiefly depth, but also position with respect to the shore and to current action) and is not determined by age differences.

Tugidak Island section:

Twenty-five species were identified in the 8 samples of this section. One sample (70APr 90) was not received. Twenty-one of these species are the same as those found in the Middleton Island section. The four different ones are all rare and seem to have no particular ecologic significance. As in the Middleton Island section, the fauna seems quite consistent and in all the samples the specimens seem fresh, similar to those in the upper part of the Middleton Island section, and not like those from the lower part. The only occurrence of Uvigerina yabei is in the highest sample. The dominating species are somewhat different. The combination of Buccella frigida and Elphidiella arctica dominating in 70APr 81 at the bottom of the section suggests a shallower depth than the combination of Elphidium clavatum and Florilus labradoricus dominating in 70APr 94 at the top of the section.

The following 14 species are not found below these two Pleistocene-Pliocene sections: Astacolus planulatus, Bulimina marginata, Cassidulina limbata, C. teretis, Dentalina frobisherensis, Elphidiella arctica, E. groenlandica, Lagena striata, Oolina hexagona, Pyrgo williamsoni, Pyrulina fusiformis, Quinqueloculina agglutinata, Rosalina ornatissima, R. wrightii.

Of these, only Elphidiella groenlandica occurs in any significant numbers.

Chaix Hills section:

The lower of these two samples contains a rich fauna of 12 species dominated by Elphidium clavatum and E. bartletti. In both species the specimens are large and well developed. The lowest sample at Samovar Hills is dominated by Buccella frigida, suggesting a change in ecology. Despite the absence of any species, other than Uvigerina yabei, that is not known also in the Recent, I would agree that this assemblage belongs with the other Pliocene sections. In preservation of specimens (shells filled or recrystallized) it resembles the older sections.

La Perouse Galcier section:

Thirty-eight species were identified in the 15 samples of this section. As compared to the sections on Middleton and Tugidak Islands, the following 10 species are new to this section: Astrononion sp., Buliminella elegantissima, Globigerina apertura, G. bulloides, G. suteri?, Nonionella miocenica, Pseudononion auricula, Quinqueloculina stalkeri, Triloculina tricarinata, Virgulina ndosa

The only one of the above that occurs more than rarely is Nonionella miocenica and its presence indicates Pliocene or Miocene age. It occurs rarely in the upper part of the section but abundantly near the bottom. The single specimen of Globigerina apertura also confirms the late Miocene to early Pliocene age of sample 63APr 137. Virgulina nodosa is another good confirmation of Pliocene age, though it has also been reported in deep basins off southern California and in the Arctic Ocean.

In the La Perouse Glacier section between 63APr 132 and 137 there is a noticeable change in preservation. Above this level the specimens are fresh, white and undeformed, almost as well preserved as in the upper part of the Middleton Island section. Below this level, specimens are darkened, filled or recrystallized, and strongly deformed.

Below these three Pliocene-Miocene sections the following species are not seen: Angulogerina fluens, Buliminella elegantissima, Cassidulina islandica, Fissurina lucida, Globigerina suteri?, Karreriella baccata, Miliolinella labiosa, Pyrgo rotalaria, Quinqueloculina agglutinata, Q. stalkeri, Triloculina tricarinata, Virgulina nodosa

Kulthieth Mtn. section:

Thirty-seven species were identified in the 16 samples of this section. Most of the samples in this section contain only meager assemblages of forams. Three exceptions are 70APr 60, 57, and 44B, and in these samples the dominating species are Cassidulina californica, C. tortuosa (but the specimens are smaller than normal), Elphidium clavatum, Haplophragmoides aff. columbiensis, and Gyroidina condoni.

Species indicative of age in this section are: Cyclammina constrictimargo, C. incisa, Globigerina apertura, G. quadrilatera, Gyroidina condoni, Haplophragmoides obliquicameratus, Melonis affinis, Nonionella miocenica, Orbulina suturalis, Uvigerina yabei

Probably Gyroidina condoni, as it first appears in 70APr 52 near the middle of the section, is the best indicator of an age change in this section. It has been reported from Eocene to Miocene. A change (ecologic or age) at this level (70APr 52) is also suggested by the appearance of Melonis affinis here. This species is a long-ranging one but its appearance in 70APr 52 may be significant of an age change.

Cyclammina incisa is reported (Asano, 1951, Illustrated Catalogue of Japanese Tertiary Smaller Foraminifera, pt. 10: Lituolidae, p. 6) to be a common Oligocene and Miocene species of the circumpacific region. Cyclammina constrictimargo appears, from its reported occurrences, to be a Pliocene fossil. Its occurrence together with C. incisa is probably determined more by the ecologic conditions favorable for the genus than by age. The genus Cyclammina is characteristically found in deep water.

Haplophragmoides obliquicameratus was described from the Miocene, Tortonian, of the Vienna Basin and has been widely reported along the Pacific coast of the United States in the Eocene and “Oligo-Miocene.”

Three of the planktonic species in this section tend to confirm the Miocene age. Orbulina suturalis ranges upward from middle Miocene. Globigerina apertura ranges from late Miocene into early Pliocene. In California Globigerina quadrilatera occurs in the Luisian and Mohnian (middle and upper Miocene) and ranges upward into the Pliocene. Globigerinids are well represented in this Miocene section and there are still a few specimens of Globigerina pachyderma, but they are in the minority. Because of the poor preservation, I am far from confident about the identifications.

Suckling Hills section:

Thirty-seven species were identified in the 11 samples of this section. None of the samples are extremely rich and there is little similarity from sample to sample except possibly between 63APr 62 and 65, and this is probably a facies similarity. Globigerinids are less well represented in this section than they are in the Kulthieth Mtn. section, and G. pachyderma makes up the majority of specimens. In this respect the section would appear to be younger than shown on your correlation chart. This younger correlation of at least the upper part of the section is further suggested by Haplophragmoides aff. major in the upper part of the section as well as by the total absence of Gyroidina condoni and the restriction to the lower part of the section of the two species of Cyclammina, Haplophragmoides obliquicameratus, Melonis affinis, Sphaeroidina variabilis, and Virgulina aff. recta.

Icy Point section:

The one sample is very poor with only a few specimens, questionably identifiable as Elphidium clavatum, too poor to provide any information about age.

Yakataga Reef section:

Forty-six species were identified – many only to the genus – in the 9 samples of this section. Only two of the samples (69APr 25 and 5) are rich and they are quite different in species composition and dominance. This difference is likely a facies difference rather than an age difference.

Most of the species in this section are the same as those already discussed under the descriptions of the Kulthieth Mtn. and Suckling Hills sections. I would estimate this section could be correlated with the lower part of the Kulthieth Mtn. section and that it should be placed below the Suckling Hills section. This conclusion is based on the occurrences of Gyroidina condoni and Melonis affinis.

I would further guess that the lower part of this Yakataga Reef section might be placed lower than the lowest part of the Kulthieth Mtn. section, as is shown on your correlation chart, because of the appearance in the basal sample (69APr 5) of a number of species not seen higher in these sections.

Below the above-discussed Miocene-Oligocene sections, over 30 species disappear. Many of them are rare, accidental, or insignificant occurrences. The major changes, however, are the disappearance of all species of Elphidium and Elphidiella, of all but a small species of Cassidulina, and of Buccella frigida, all of which occupy positions of dominance in the younger sections. In addition, Cibicides lobatulus is replaced by C. pseudoungerianus and Glandulina laevigata by its subspecies ovata, and Uvigerina yabei by two different species, one costate and the other hispid.

Kayak Island section:

The seven samples from this section contain 58 identified species. In general, the assemblages are dominated by agglutinated forms. Dominant species are Haplophragmoides obliquicameratus, Gaudryina gracilis, Cyclammina incisa, Cibicides pseudoungerianus, and Alabamina aff. wilcoxensis.

I note the relative position of the samples is uncertain due to faulting. Two samples (63APr 124 and 127) appear to be virtually identical in species composition and dominance. Two other samples (63APr 94 and 103), both having rather meager faunas, have a few species in common with each other and not with the other 5 samples.

I cannot see any close relationship between any two other samples and I doubt I could make any safe estimate as to the age sequence of these 7 samples, except to guess that 63APr 126 and 120 might be younger than the other 5 samples.

Age indications of the various significant species not already discussed under the younger sections are as follows:

Miller Hills section:

The 4 samples in this section contain very meager assemblages. A total of 10 species were found. The best fauna of 7 species is in 63APr 72. The poverty and poor preservation of these assemblages prevent my confirming their placement in the Oligocene. The globigerinid, Globigerina suteri, ranges from middle Eocene to early Miocene, but its identification cannot be relied upon. Three deformed specimens of Nonionella miocenica indicate Miocene or Pliocene age. The other species are either questionable or not stratigraphically restricted.