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Publications | 1993 - 95

Research Publications (1993 - 95)

Patterson, R.T., Barker, T., and Burbidge, S.M.,1996, Arcellaceans (Thecamoebians) as Proxies of Arsenic and Mercury Contamination in Northeastern Ontario Lakes. Journal of Foraminiferal Research (no. 2, April).


Asioli, A., Medioli, F.S., and Patterson, R.T.,1996, Thecamoebians as the tool for reconstruction of paleoenvironments in some southern Alpine Lakes (Orta, Varese and Candia). Journal of Foraminiferal Research.


Reinhardt, E.G., Easton, N., Patterson, R.T., 1996, Foraminiferal evidence of late Holocene sea-level change on Amerindian site distribution at Montagu Harbour, British Columbia. Geographie Physique et Quaternaire.


Patterson, R.T., Guilbault, J.-P., Thomson, R.E., and Luternauer, J.L. 1995, Foraminiferal Evidence of Younger Dryas isochronous cooling on the British Columbia shelf, west coast of Canada. Geographie Physique et Quaternaire, 49 (no. 3).


Patterson, R.T., Cavazza, W., and Blenkinsop, J., 1995, Planktic foraminiferal biostratigraphy and 87Sr/86Sr Isotopic stratigraphy of the Oligocene-to Quaternary sedimentary sequence in the southern Calabrian-Peloritani Arc, southern Italy: Journal of Paleontology, 69: 7-20


Patterson, R.T., and Burbidge, S.M., 1995, New Late Oligocene to Pleistocene hyaline calcareous unilocular foraminifera from DSDP Site 357 (Leg 39) on the Rio grande Rise, southwest Atlantic Ocean. Journal of Paleontology, 69: 635-655.


Jonasson, K.E., Schröder-Adams, C.J. and Patterson, R.T.,1995,Benthic foraminiferal distribution at Middle Valley, Juan de Fuca Ridge: a Northeast Pacific hydrothermal venting site. Marine Micropaleontology, 25: 151-167.


Clark, F., Patterson, R.T., and Fishbein, E, 1994, Distribution of Holocene benthic foraminifera from the tropical southwest Pacific Ocean. Journal of Foraminiferal Research, 24: 241-267


Reinhardt, E.G., Patterson, R.T., and Schröder-Adams, C.J. 1994, Geoarchaeology of the ancient harbor site of Caesarea Maritima, Israel: evidence from sedimentology and paleoecology of benthic foraminifera. Journal of Foraminiferal Research, 24:37-48.


McKillop,W.B., Patterson, R.T., Delorme, L.D., Nogrady, T. 1992 (published in 1994). The origin, physico-chemistry and biotics of sodium chloride dominated saline waters on the western shore of Lake Winnepegosis, Manitoba. Canadian Field-Naturalist, 106:454-473. 

Patterson, R.T., 1993. Late Quaternary benthic foraminiferal biofacies and paleoceanography of Queen Charlotte sound and southern Hecate Strait, British Columbia. Journal of Foraminiferal Research, 23:1-18. 


Patterson, R.T., Cavazza, W., and Blenkinsop, J. 1993.Tortaguttus stiloensis, a new species of foraminifera from the Plio-Pleistocene of Calabria, Italy: Transactions of the American Microscopical Society, 112:168?171. 


Evoy, R.W., Moslow, T.F., Patterson, R.T., and Luternauer, J.L. 1993. Patterns and variability in sediment accumulation rates, Fraser River delta foreslope, British Columbia, Canada. Geo-Marine Letters, 13:212-218 


Fishbein, E., and Patterson, R.T., 1993. "Error weighted maximum likelihood (EWML)" a new statistically valid method to cluster quantitative micropaleontological data. Journal of Paleontology, 67:475-486. 


Mathewes, R.W., Heusser, L.E., and Patterson, R.T., 1993.Evidence for a Younger Dryas-like cooling event on the British Columbia coast. Geology, 21:101-104. 


Clark, F., and Patterson, R.T., 1993. A taxonomic key to the unilocular genera of calcareous foraminifera. Journal of Paleontology, 67:20-28. 


Josenhans, H.W., Barrie, J.V., Conway, C., Patterson, R.T., Mathewes, R.W. and Woodsworth, G.J. 1993. Surficial geology of the Queen Charlotte Basin: evidence of submerged proglacial lakes at 170 m on the continental shelf of western Canada. Current Research, Paper 93-1A: 186?192 


Patterson, R.T., and Luternauer, J.L. 1993. Holocene foraminiferal faunas from cores collected on the Fraser River delta, British Columbia: a paleoecological Interpretation: Current Research, Paper 93-1A:245-254. 


Arcellaceans (Thecamoebians) as Proxies of Arsenic and Mercury Contamination in Northeastern Ontario Lakes.

R.T. Patterson, T. Barker, and S.M. Burbidge

Journal of Foraminiferal Research (1996) v. 26 (no. 2).
 
 


Abstract

 Q-mode cluster analysis of arcellacean populations in three small lakes (two heavily polluted by mine tailings) near the town of Cobalt in northeastern Ontario permitted five distinct faunal assemblages to be recognized and related to ecologic tolerance. Mine waste and mill tailings were dumped into Crosswise Lake until 1970, and a leaking tailings dam continues to pollute Peterson Lake. Natural sedimentation is slowly burying the tailings in these lakes but areas of highly toxic sediments remain exposed in several areas. Levels of arsenic and mercury contamination in the substrate are as high as 7110 ppm and 2.54 ppm, respectively, in Crosswise Lake; and 8330 ppm and 0.77 ppm, respectively, in Peterson Lake (maximum acceptable concentrations for aquatic life are 50 ppm and 0.100 ppm, respectively). A Contaminated Substrate Assemblage (1), dominated by Centropyxis aculeata (x=27.5%), Centropyxis constricta (x=13.5%), and Arcella vulgaris (x=9.7%), characterizes the most heavily polluted parts of the lakes. Centropyxids, known to be opportunistic and capable of withstanding hostile conditions, become less dominant in biofacies found in substrates characterized by progressively less mine tailing contamination (Mine Tailings Assemblage [2], Muddy Substrate Assemblage [3], and Diatom Mud Assemblage [4]).

Unpolluted Gillies Lake was not comparable with Crosswise or Peterson lakes as a pronounced thermocline results in significantly different limnological conditions (i.e., very low bottom temperatures and oxygen concentrations) in that lake. The presence of a Cucurbitella tricuspis (x=90.3%) dominated fauna (Transported Fauna Assemblage [5]) in most Gillies Lake samples is enigmatic as no significant populations of Spirogyra spp., the algae with which the partially planktic Cucurbitella tricuspis has a symbiotic relationship, have been observed. We suspect that Assemblage 5 is allochthonous.

The results of this pilot study indicate that arcellaceans are useful not only to monitor environmental pollutants but to assess rates of lake remediation.

 


Thecamoebians as the tool for reconstruction of paleoenvironments in some southern Alpine Lakes (Orta, Varese and Candia).

A. Asioli, F.S. Medioli, and R.T. Patterson,

Journal of Foraminiferal Research (1996) v. 26 (no. 3)


Abstract

 A study of Thecamoebians was carried out on three sediment cores collected in three Northern Italian lakes (Orta, Varese, Candia). The recognition of distinct morphotypical populations ("morphs ") within three species of thecamoebians in varying paleolomnological settings has resulted in a refined understanding of the environmental parameters controlling their distribution. For example: D. proteiformis morph "proteiformis" is well adapted to environments rich in organic matter and sulphides while D. proteiformis morph "rapa" tolerates polluted and acidified waters (presence of: copper sulfates, ammonium sulfates, high content of ammonium and nitrite nitrogen, and water with pH values between 3.9 and 4.5).

Although most questions about the ecology of thecamoebians are still unresolved, this study strongly suggests that with further research these Protozoa can be used as a valuable tool for paleoenvironmental reconstructions and detection of environmental deterioration.


Foraminiferal evidence of late Holocene sea-level change on Amerindian site distribution at Montagu Harbour, British Columbia.

E.G. Reinhardt, N. Easton, R.T. Patterson

Geographie Physique et Quaternaire. (1996)
 
 


Abstract

 Foraminiferal and sedimentological analysis of an underwater stratigraphic section from an Amerindian habitation site at Montague Harbour, British Columbia has further documented late Holocene sea level changes. It appears that part of the documented transgression was caused by tectonic subsidence of the area (Event 1 at approx. 3500 calendar years BP and Event 2 sometime before 1100 calendar years BP) and was recognized in the stratigraphic record by rapid environmental changes. The environmental changes caused by rapid shifts in water depth were recognized through sedimentological and foraminiferal evidence. The tectonic subsidence events, coupled with gentle late Holocene transgression, caused the breaching of Montague Harbour's northwestern channel. The breaching of the channel improved water circulation and increased salinity within the harbour. The salinity changes are reflected in the shift from a low salinity Cribroelphidium excavatum (Terquem, 1876) phenotype "clavata" dominated biofacies (1) at the base of the section to a higher salinity Buccella tenerrima (Bandy, 1950) and Elphidiella hannai (Cushman and Grant, 1927) dominated biofacies (2) at the top. These sea-level changes would have eventually forced local Amerindian settlements inland. The 14C dating of wood and shell, indicates that the recovery of archaeological remains of the Charles culture (ca.6500-3200 years BP) requires investigation in deeper waters.


Foraminiferal Evidence of Younger Dryas isochronous cooling on the British Columbia shelf, west coast of Canada.

R.T. Patterson, J.-P. Guilbault, R.E. Thomson, and J.L. Luternauer

G*ographie Physique et Quaternaire, (1995) 49 (no. 3).
 
 


Abstract

 Foraminiferal analysis was carried out on a 12,000 - 9,000 years old piston core from Goose Island Trough, Queen Charlotte Sound, on the British Columbia shelf. Cluster analysis of the data resulted in the recognition of five separate faunas related to distinct paleoceanographic phases. These results provide detailed information on the paleoceanographic conditions that prevailed during passage of a late Quaternary glacial isostatic forebulge across the region, and during a cool interval correlatable with the Younger Dryas cold stadial.

Passage of the glacial forebulge (beginning 11,470-11,260 years BP and terminating prior to 10,000 years BP) resulted in a gradual decrease in water depth to ~75-90 m at the core site, based on sedimentological data and increasing proportions of shallow-water benthic foraminifera. In the early stages of the regression, circulation remained open and salinity at near normal marine levels, as indicated by the high Shannon diversity indexes (up to 2.5) and the high proportion of planktic foraminifera. The fall in the proportion of planktic foraminifera from 11.8 to 2.6% suggests that the area became more isolated from the open ocean late in the regression. Near glacial conditions between ~11,100 ? 10,000 years BP at this locality are unrelated to passage of the glacial forebulge. The presence of very cold low-salinity water in the area is shown by high proportions of Cassidulina reniforme and Islandiella helenae. The depressed salinity and temperature may have resulted from a modification of regional weather patterns during the Younger Dryas cold phase. Decreased mean continental summer temperatures could have reduced the seasonal influence of the North Pacific High and lengthened that of the Aleutian Low. This would have resulted in a near continuous surface onshore Ekman transport, which combined with enhanced coastal runoff, would have effectively blocked the movement onto the shelf of deep, saline and less cold water of the California Undercurrent. The resultant isolated inshore basin comprised of the present-day Hecate Strait and Queen Charlotte Sound is tentatively named the "Hecate Sea".

By ~10,000 years BP the Younger Dryas?like cooling event had terminated and weather and oceanographic circulation had returned to near modern patterns as indicated by the near replacement of Islandiella helenae by Nonionellina labradorica and by the development of a modern Epistominella vitrea dominated biofacies. Paleoceaonographic details associated with the termination of the cooling event are difficult to determine precisely due to the rapid increase in water depth at this locality after 10,000 years BP. Once water depth reached 100 m the site may once again have been influenced by upwelling, resulting in the climate signal blending with a water depth signal.


Planktic foraminiferal biostratigraphy and 87Sr/86Sr Isotopic stratigraphy of the Oligocene-to Quaternary sedimentary sequence in the southern Calabrian-Peloritani Arc, southern Italy

R.T. Patterson, W. Cavazza, and J. Blenkinsop,

Journal of Paleontology, (1995), v. 69, p. 7-20


Abstract

 Integration of foraminiferal biostratigraphy, 87Sr/86Sr isotope stratigraphy and traditional physical stratigraphy has provided a refined age control of a poorly known Oligocene-to-Pleistocene sedimentary sequence covering nonconformably the crystalline basement complex of the Calabria-Peloritani arc (CPA), a continental block which rifted off the southern margin of the European plate during Neogene time. In spite of the fossil poor content of the sequence, the simultaneous use of paleontological and geochemical techniques have resulted in the following conclusions. 1) The age of an unnamed, thin calcarenite unit locally present at the base of the sequence, previously considered Rupelian to early Aquitanian in age, has been refined to Chattian (27-26 Ma). This calcarenite was considered a basal, conformable member of the overlying Stilo - Capo d'Orlando Formation (SCO Fm). However, this study indicates that it is separated from the SCO Fm either by an angular unconformity or by a disconformity representing a significant time interval. 2) The SCO Fm has a latest Chattian/ earliest Aquitanian-Burdigalian age. Previously published reports suggested deposition over a much longer time span, ranging from late Rupelian to Langhian. 3) An unnamed deep-marine siliciclastic unit mostly composed of conglomerate and sandstone and previously considered Tortonian in age is, in fact, Serravallian to Tortonian. 4) The depositional interval of the "trubi", fine grained marine deposits, has been independently confirmed to span the Pliocene?Pleistocene.

The results of this study provide a framework for future sequence-stratigraphic and paleotectonic studies in the area, and prove the effectiveness of an integrated paleontological/geochemical (87Sr/86Sr ) approach in the study of fossil-poor sedimentary sequences.


New Late Oligocene to Pleistocene hyaline calcareous unilocular foraminifera from DSDP Site 357 (Leg 39) on the Rio grande Rise, southwest Atlantic Ocean.

R.T. Patterson and S.M. Burbidge,

Journal of Paleontology, (1995), v. 69, p.635-655


Abstract

 Thirty-two new species of unilocular benthic foraminifera were described from 50 Late Oligocene to Pleistocene samples from DSDP Site 357 (Leg 39) on the Rio Grande Rise in the southwest Atlantic Ocean. These new species make up nearly one-third of the 112 species of unilocular foraminifers identified in the core. Such a high proportion of new taxa is not unexpected as the group has been ignored by most researchers.

New taxa described include Lagena praemeridionalis, Lagena rotundocostatina, Exsculptina sicula, Exsculptina umbelliforma Patterson and Cavazza, Favulina prolatella, Favulina quasiperthensis, Galwayella copiosotubula, Galwayella oscula, Galwayella spherula, Homalohedra anastomocostata, Homalohedra goniachrados, Homalohedra gothicofenestella, Homalohedra polykamptarion, Lagnea congestacolla, Lagnea derbiosa, Oolina curvella, Vasicostella lecythella, Vasicostella spinulafunda, Fissurina anapetebasilaris, Fissurina binaroculella, Fissurina favobasella, Fissurina fissuroscula, Fissurina labeona, Lagenosolenia angula, Lagenosolenia penna, Palliolatella anfracta, Palliolatella hadrocheilos, Pseudoolina becella, Pseudoolina oscillum, Parafissurina kladerorhektis, Parafissurina prolatolonga, and Pseudofissurina plastica. The new name, Lagenosolenia incompta,a is proposed for Lagena bicarinata (Terquem) var. polita Matthes, 1939.


Benthic foraminiferal distribution at Middle Valley, Juan de Fuca Ridge: a Northeast Pacific hydrothermal venting site.

K.E. Jonasson, C.J. Schroder-Adams, and R.T. Patterson

Marine Micropaleontology, (1995) v. 25, p. 151-167.


Abstract

 Fourteen benthic foraminiferal bearing surface samples collected from the Area of Active Venting (AAV) in Middle Valley at a depth of 2430 m at the northern end of Juan de Fuca Ridge, northeast Pacific Ocean, yielded 156 identifiable taxa. Sample sites were selected near active or recently active vents, where temperatures up to 274 degrees C have been measured. Agglutinated foraminifera dominate within the AAV. However, like the macrofauna observed near hydrothermal vents, foraminfiera do not venture into the extreme habitats where temperatures are greater than 20 degrees C. Where clam beds are found in association with active hydrogen sulphide venting, benthic foraminifera occur rarely. Low foraminiferal abundance and species diversity at the immediate site of active venting is attributed to rapid changes in physical and chemical conditions caused by circulating hydrothermal vent waters.


Distribution of Holocene benthic foraminifera from the tropical southwest Pacific Ocean.

F. Clark, R.T. Patterson, and E. Fishbein

Journal of Foraminiferal Research, (1994) v. 24, p. 241-267


Abstract

 A suite of 62 surface and near surface samples has been examined for its benthic foraminiferal faunas. The cores sampled ranged from 110 to 8900 m water depth, and are distributed across the tropical southwest Pacific Ocean, north and east of Australia. A total of 606 species were identified. Census data was obtained for each sample, and species found in statistically significant fractional abundances (88 in all) were analyzed using a new Q-mode clustering algorithm (Error Weighted Maximum Likelihood [EWML]). Both the full data set, and an edited data set comprising 44 samples and 39 species, were analyzed. With the aid of these analyses ten benthic foraminiferal assemblages were identified. Three manually constrained assemblages, each represented by a single sample, were recognized. Five statistically constrained assemblages were recognized, each having a water depth range coincident with the range of known water masses of the region. The Astrononion echolsi-Cassidulina teretis Assemblage and the Nuttalites bradyanus Assemblage were developed in samples from depths bathed by waters of the Deep Oxygen Minimum, the Epistominella exigua-Globocassidulina rarilocula Assemblage was developed in samples from depths bathed by Deep Water, a derivative Antarctic Bottom Water, and both the Globocassidulina subglobosa-Pseudoparrella parca Assemblage and the Nuttalides umboniferus Assemblage were developed in samples from depths bathed by Antarctic Bottom Water proper. From depths very near the calcite compensation depth (CCD), a Mixed Calcareous/Agglutinated Abyssal Assemblage was developed in a pair of samples, whereas below the CCD, the tenth assemblage, the Abyssal Agglutinated Assemblage, was developed, with only a few corroded calcareous specimens accompanying the agglutinated benthic faunas. These latter two assemblages were also manually constrained.


Geoarchaeology of the ancient harbor site of Caesarea Maritima, Israel: evidence from sedimentology and paleoecology of benthic foraminifera.

E.G. Reinhardt, R.T. Patterson, and C.J. Schroder-Adams,

Journal of Foraminiferal Research, (1994) v. 24, p. 37-48.


Abstract

 Foraminiferal analysis and 14C dating of a core obtained from the entrance of the ancient harbor site of Caesaria Maritima, Israel provided paleo-environmental information which has enhanced previous archaeological intepretations. This integrated micropaleontological-sedimentological approach presents a new tool for solving marine archaeological problems. Four distinct sedimentological units related to the harbor's history were recognized: preharbor deposits, harbor construction rubble, harbor and post- harbor deposits. The sediments from the active harbor were characterized by mud, interrupted by intervals of coarse sand deposited during large low periodicity (25-50 years) storms. The area outside the harbor moles was continuously under the influence of wave action resulting in deposition of a coarse sandy substrate. Sedimentological and foraminiferal evidence as well as 14C dates indicated that the mud was from the active harbor (commissioned in 21 BC) and that the harbor was no longer functioning according to its original design by the mid third century and definitely by no later than 490 AD. Previous research suggested that the degradation of the harbor was most likely related to tectonic movement of the area. However, the timing of this event was not exactly known. Archaeologists have speculated that the Byzantine Emperor Anastasius I refurbished the harbor in the early 6th century. The results of this study have indicated that, even if this reconstruction did occur, the harbor was not returned to ites original design or function.


The origin, physico-chemistry and biotics of sodium chloride dominated saline waters on the western shore of Lake Winnepegosis, Manitoba.

W.B.McKillop, R.T. Patterson, D.L. Delorme, and T. Nogrady

Canadian Field-Naturalist, 1992 (published in 1994). v. 106, p. 454-473.


Abstract

 Twenty-three sodium chloride dominated saline sites clustered along the western shore of Lake Winnipegosis were studied over a three year period. Sites were classified into four habitat categories based in part on salinity, which frequently exceeded that of oceanic environments. The source of the saline waters together with associated physico-chemical factors and unique biological communities are described. In addition to an unique flora, members of five animal phyla; Chordata, Protozoa, Rotifera, Arthropoda, and Mollusca, were present. Of these only the Mollusca lacked marine representation. Transport of the marine species by birds from coastal areas is suggested.

Late Quaternary benthic foraminiferal biofacies and paleoceanography of Queen Charlotte sound and southern Hecate Strait, British Columbia.

R.T. Patterson

Journal of Foraminiferal Research, (1993) v. 23, p. 1-18.


Abstract

A high resolution analysis was carried out on the foraminiferal faunas from the 13,000 ? 9000 years B.P. piston core END 84B-10 from Goose Island Trough, Queen Charlotte Sound, on the British Columbia shelf. Cluster analysis of the data resulted in the recognition of five separate faunas related to distinct paleoceanographic phases during the late Quaternary history of the site. In particular, these results provide detailed information on the paleoceanographic conditions that prevailed in the area: (1) during passage of a late Quaternary glacial forebulge across the region; and (2) during development and waning of the west coast Younger Dryas?like isochronous cooling event.

Passage of the glacial forebulge across this core site (beginning 11,470-11,260 years B.P. and terminating prior to 10,000 years B.P.) resulted in a gradual decrease in water depth to 70?85 m, based on sedimentological data and increasing proportions of Buliminella elegantissima. In the early stages of the regression circulation remained open and salinity at near normal marine levels despite the emergence of a number of nearby large islands, as indicated by the high Shannon?Weiner diversity indexes (up to 2.5), the high proportion of planktic foraminifera, and the presence of deep shelf phenotypes of Cribroelphidium hallandence. However, the continued emergence of nearby islands began to constrict local waterways, as suggested by the fall in the proportion of planktic foraminifera from 11.8 to 2.6% over the course of the regression.

Near glacial conditions between 11,260 ? 10,000 years B.P. at this locality are unrelated to passage of the glacial forebulge. The inundation of very cold water over the area is evidenced by the presence of high proportions of Cassidulina reniforme and Cassidulina helenae. Abundant Cassidulina helenae is also indicative of depressed salinities The presence of some temperate species provides evidence that any local glacial advances were restricted to coastal fjords, some distance away. The observed depressed salinity and temperature regime may have resulted from a slight modification of existing regional seasonal weather patterns associated with the hemispheric, or global, climatic changes accompanying the Younger Dryas cooling event. Decreased mean continental summer temperatures could have resulted in a reduced influence of the North Pacific High and a lengthening of the seasonal influence of the Aleutian Low. Oceanographically this would have resulted in a near continuous onshore Ekman flow and resultant downwelling, carrying cold, low salinity surface plumes to depth.

By 10,000 years B.P. the west coast Younger Dryas?like cooling event had terminated and weather and oceanographic circulation had returned to near modern patterns as indicated by the near replacement of Cassidulina helenae by Nonionellina labradorica and the development of a modern shelf Epistominella vitrea dominated biofacies.



Tortaguttus stiloensis, a new species of foraminifera from the Plio-Pleistocene of Calabria, Italy

R.T. Patterson, W. Cavazza, and J. Blenkinsop

Transactions of the American Microscopical Society, (1993) v. 112, p. 168?171.

Abstract

 Tortaguttus stiloensis, a new species of benthic foraminifera is described from Middle Pleistocene sediments of Calabria, Italy. This species is characterized by radiating elevated costae on the surface of a double marginal carinae connected by numerous cross?struts.



Patterns and variability in sediment accumulation rates, Fraser River delta foreslope, British Columbia, Canada.

R.W. Evoy, T.F. Moslow, R.T. Patterson, and J.L. Luternauer

Geo-Marine Letters, (1993) v. 13, p. 212-218

Abstract

 Minimum sediment accumulation rates on the Fraser River delta foreslope exhibit a high degree of spatial variation, with accumulation rates ranging from 0.50 to 3.0 cm/yr. Accumulation rates generally increase towards Sand Heads channel, the active foreslope depocenter. Sedimentation rates and patterns and micropaleontological assemblages are interpreted to reflect reintroduction of older sediment from upslope via slumping and sediment-gravity flow processes. Such processes account for the bulk of sedimentiton in much of the subaquaeous delta. These processes provide a mechanism for sand bypassing of the delta plain and foreslope and for deliver of coarse-grained sediment directly to prodelta and basinal environments.



"Error weighted maximum likelihood (EWML)" a new statistically valid method to cluster quantitative micropaleontological data.

E. Fishbein, and R.T. Patterson

Journal of Paleontology, (1993), v. 67, p. 475?486.

Abstract

 The advent of readily-available computer-based clustering packages has created some controversy in the micropaleontological community concerning the use and interpretation of computer based biofacies discrimination. This is because dramatically different results can be obtained depending on methodology. The analysis of various clustering techniques reveals that in most instances, no statistical hypothesis is contained in the clustering model and that no basis exists for accepting one biofacies partitioning over another. Furthermore most techniques do not consider standard error in species abundances and generate results that are not statistically relevant. When many rare species are present, accumulated statistically insignificant differences in rare species can overshadow the significant differences in the major species leading to biofacies containing members having little in common.

A statistically-based "error-weighted maximum likelihood" (EWML) clustering method is described that determines biofacies by assuming samples from a common biofacies are normally distributed. This method also weights species variability to be inversely proportional to measurement uncertainty. The method has been applied to samples collected from the Fraser River Delta marsh and shows that five distinct biofacies can be resolved in the data. Similar results were obtained from readily available packages when the data set was preprocessed to reduce the number of degrees of freedom. Based on the sample results from the new algorithm, and on tests using a representative micropaleonotological data set, a more conventional iterative processing method is recommended. This method, although not statistical in nature, produces similar results to EWML (not commercially available yet) with readily available analysis packages. Finally, some of the more common clustering techniques are discussed and strategies for their proper utilization are recommended.



Evidence for a Younger Dryas-like cooling event on the British Columbia coast.

R.W. Mathewes, L.E. Heusser, and R.T. Patterson

Geology, (1993) v. 21, p. 101-104.

Abstract

 Two independent paleoclimatic records from the Pacific coast of Canada indicate that a late-glacial warming trend was interrupted by a return to colder conditions between about 11,000 and 10,200 radiocarbon yr. B.P., correlative with the classical Younger Dryas chronozone of the North Atlantic region. Fossil benthic foraminifera from three cores from the continental shelf dated by accelerator mass spectrometry show peak abundances of the cold-water indicator species Cassidulina reniforme at this time. Fossil-pollen spectra from two sites on the Queen Charlotte Islands record a shift from forest to open, herb-rich vegetation after 11,100 year B.P., probably in response to colder and wetter conditions identified by pollen-climate transfer functions. These preliminary data for a cold oscillation between ca. 11,000 and 10,000 yr ago in the northeast Pacific argue that this deglacial phenomenon was not restricted to the North Atlantic, but was a hemispheric -- and possibly global -- event.



A taxonomic key to the unilocular genera of calcareous foraminifera.

F. Clark and R.T. Patterson

Journal of Paleontology, (1993), v. 67, p. 20-28.

Abstract

 Taxonomic keys are rarely used as an aid to the identification of foraminifera. Such keys become increasingly attractive, however, as the number of taxa which must be distinguished becomes large. The proliferation of known genera over the last 25 years is nowhere more apparent than in the unilouclar foraminifera, where the number of genera has risen from five to 46. We present herein a dichotomous key in which any species may be assigned to its proper genus by progressing through a series of steps, consisting of paired statements, in which only one choice is made at a time.



Surficial geology of the Queen Charlotte Basin: evidence of submerged proglacial lakes at 170 m on the continental shelf of western Canada.

H.W. Josenhans,J.V. Barrie, C. Conway, R.T. Patterson R.W. Mathewes, and G.J. Woodsworth

Current Research, (1993), Paper 93-1A, p. 186?192
 
 

Abstract

 A high resolution marine seismic and sampling program in the region was carried out during a 12 day cruise aboard the research vessel CFAV Endeavour. Preliminary results indicate that grounded glaciers deposited sediments in the deep troughs which indent the continental shelf as far west as the shelf break. Offlapping till tongues found in the troughs indicate that ice retreated stepwise from Queen Charlotte Sound at the closed of the last (Late Wisconsinan) glaciation. Detailed studies of submerged shoreline deposits define the volume and frequency of failure of steeply dipping prograde sand and gravel deposits.



Holocene foraminiferal faunas from cores collected on the Fraser River delta, British Columbia: a paleoecological Interpretation.

R.T. Patterson

Current Research, (1993), Paper 93-1A, p. 245-254.
 
 

Abstract

 Interpretation of sedimentary environments are made based on the foraminiferal faunas recovered from four cores (FD90-A, FD90-B, FD91-1, and FD91-2) collected on the Fraser delta. These relatively short cores (<55 m) are primarily comprised of prodelta sands overlying ancetral Strait of Georgia mud and silt. The muds and silts are characterized by a low diversity foraminifera fauna, dominated by Buccella frigida, Cribroelphidium excavatum, and Elphidiella hannai. This fauna is typical of low salinity, neritic depth conditions. foraminifera are virtually absent from the prodelta sands as the winnowing conditions prevalent during deposition of this unit made colonizaiton difficult.

 

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Updated: April 16, 2014