Benthic foraminiferal census data and radiocarbon dates from the Gulf of Mexico (Matagorda 1A Core)

2000 ◽  
Author(s):  
Lisa E. Osterman ◽  
Richard Z. Poore ◽  
Elizabeth D. Castenson
Keyword(s):  
Gulf Of Mexico ◽  
Census Data ◽  
Radiocarbon Dates

Chronology of glacial Lake Agassiz meltwater routed to the Gulf of Mexico

2003 ◽  
Vol 59 (2) ◽  
pp. 271-276 ◽  
Author(s):  
Timothy G. Fisher
Keyword(s):  
Gulf Of Mexico ◽  
Sediment Cores ◽  
Glacial Lake ◽  
Mississippi Valley ◽  
Lake Agassiz ◽  
Radiocarbon Dates ◽  
Glacial Lake Agassiz ◽  
Radiocarbon Chronology

AbstractSediment cores with new radiocarbon dates from the southern outlet of glacial Lake Agassiz indicate that meltwater delivery to the Mississippi valley was disrupted at 10,800 14C yr B.P. and the outlet was abandoned by 9400 14C yr B.P. These findings confirm the timing of generally accepted terminations of the Lockhart and Emerson Phases of Lake Agassiz. Additionally, the radiocarbon chronology indicates that the spillway was fully formed by 10,800 14C yr B.P. and that the occupancy in late-Emerson time was likely short-lived with minimal spillway erosion.

From source to sink: Glacially eroded, Late Devonian algal “cysts” (Tasmanites) delivered to the Gulf of Mexico during the Last Glacial Maximum

2020 ◽  
Author(s):  
Barry Kohl ◽  
B. Brandon Curry ◽  
Merrell Miller
Keyword(s):  
Gulf Of Mexico ◽  
Last Glacial Maximum ◽  
Lake Michigan ◽  
Clay Fraction ◽  
Black Shales ◽  
Glacial Maximum ◽  
Long Distance ◽  
Radiocarbon Dates ◽  
Last Glacial ◽  
Source To Sink

The source of reworked Devonian algal “cysts” in last glacial maximum (LGM) sediment in the Gulf of Mexico is traced to their host black shales, which ring the southwestern Great Lakes. The source-to-sink pathway includes intermediate storage in fine-grained LGM glacial lacustrine sediment and till. The “cysts” are pelagic chlorophyllous algae (Tasmanites and Leiosphaeridia), collectively referred to herein as tasmanitids. Radiocarbon dates of syndepositional Gulf of Mexico foraminifera, derived from accelerator mass spectrometry, bracket the Gulf of Mexico sediment age with common tasmanitids from 28.5 ± 0.6−17.8 ± 0.2 cal kyr B.P. Approximately 1400 km north of the Gulf of Mexico, tasmanitids are abundant in Upper Devonian black shales (New Albany, Antrim, and Ohio Shales) that ring the Michigan, Illinois, and Appalachian intracratonic basins. Tasmanitids were eroded from bedrock and incorporated in glacial sediment dating from ca. 28.0−17.6 cal kyr B.P. by the Lake Michigan, and Huron-Erie lobes of the Laurentide Ice Sheet. The physical characteristics of tasmanitids are ideal for long-distance transport as suspended sediment (density: 1.1−1.3 g/cc, size ranging from 63 µm to 300 µm), and these sand-sized tasmanitids traveled with the silt-clay fraction. Thus, the source-to-sink journey of tasmanitids was initiated by subglacial erosion by water or friction, sequestering in till or glaciolacustrine sediment, re-entrainment and suspension in meltwater, and final delivery in meltwater plumes to the Gulf of Mexico. River routes included the Mississippi, Illinois, Ohio, Wabash, Kaskaskia, and many of their tributaries. Reworked Devonian tasmanitids are a previously unrecognized link between their occurrence in deep-water deposits of the Gulf of Mexico and the late Wisconsin glacial history of the Upper Mississippi Valley. We propose that tracking occurrences of tasmanitid concentrations from the source area to sink, along with adjunct proxies such as clay minerals, will facilitate a more refined analysis of the timing and duration of megafloods. This study also demonstrates that isotopically dead carbon, from reworked Devonian tasmanitid “cysts,” can contaminate radiocarbon dating of LGM bulk sediment samples toward older ages.

Paleoceanography of Surface Waters in the Gulf of Mexico during the Late Quaternary

1982 ◽  
Vol 17 (1) ◽  
pp. 105-119 ◽  
Author(s):  
Charlotte A. Brunner
Keyword(s):  
Gulf Of Mexico ◽  
Surface Waters ◽  
Census Data ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Glacial Maximum ◽  
Central Basin ◽  
Circular Pattern ◽  
Climatic Optimum ◽  
Mexico Basin

AbstractLate Quaternary paleotemperatures and paleosalinities of surface waters of the Gulf of Mexico were estimated using a multivariate statistical analysis of census data of planktonic foraminifera. Two climatic extremes were selected for detailed basinwide study, the climatic optimum 125,000 yr ago and the glacial maximum 18,000 yr ago. In addition, patterns of climatic change were examined in seven piston cores from 127,000 yr ago to the present day. During the climatic optimum 125,000 yr ago temperature distributions in surface waters were similar to those of the present. The 22°C winter isotherm trended northeastward across the central basin and paleotemperatures decreased northward. Summer distributions were nearly homogeneous and ranged between 28° and 29°C. Winter salinities were 1‰ fresher than present values in the northmost Gulf and 0.4‰ fresher in the central basin. Summer salinities were similar during both times. In contrast, during the last glacial maximum temperatures were 1° to 2°C cooler in winter and 1°C cooler in summer, and isotherms formed a circular pattern in the Gulf during both seasons. Salinity was 0.3‰ fresher in winter than at present but 0.6‰ saltier in summer. Conditions deteriorated from the climatic optimum to the glacial maximum. In the Mexico Basin, winter temperatures were 2°C cooler from 75,000 to 45,000 yr ago (Y6 to Y3 Subzones), summer temperatures reached a minimum (3°C cooler) 32,000 yr ago (Y2–Y3 boundary), and seasonality reached minimal values (5°C) from 45,000 to 15,000 yr ago. All three parameters became similar in value to those in the Straits of Florida from 45,000 to 15,000 yr ago, suggesting that the exchange of surface waters was enhanced at this time between the two regions. Summer salinities remained similar to present conditions in the Mexico Basin, whereas, winter salinities increased 2‰ by 32,000 yr ago and then fell 0.5‰ until the glacial maximum ended. The Westerlies may have migrated southward over the Mexico Basin in winter from 32,000 to 15,000 yr ago.

scholarly journals Texas A & M University Radiocarbon Dates III

Radiocarbon ◽  
1975 ◽  
Vol 17 (2) ◽  
pp. 216-218
Author(s):  
C W Lindau ◽  
W M Sackett ◽  
C W Poag
Keyword(s):  
Gulf Of Mexico ◽  
The West ◽  
Radiocarbon Dates ◽  
Amphistegina Gibbosa ◽  
Foraminiferal Species

This date list is composed of the ages of tests of fossil populations of the foraminiferal species, Amphistegina gibbosa, and algal nodules collected from submerged banks in the N Gulf of Mexico. A Shipek grab sampler was used to collect the Amphistegina gibbosa and a few of the algal nodule samples. Algal nodules from the West Flower Garden Bank were obtained from cores at various intervals as indicated in Sec III.

scholarly journals Paired AMS 14C Dates on Planktic Foraminifera from a Gulf of Mexico Sediment Core: An Assessment of Stratigraphic Continuity

Radiocarbon ◽  
2011 ◽  
Vol 53 (2) ◽  
pp. 337-344 ◽  
Author(s):  
B P Flower ◽  
D W Hastings ◽  
N J Randle
Keyword(s):  
Gulf Of Mexico ◽  
Sediment Core ◽  
Deep Sea ◽  
Sediment Cores ◽  
High Accumulation ◽  
Planktic Foraminifera ◽  
Globigerinoides Ruber ◽  
Radiocarbon Dates ◽  
Deep Sea Sediment ◽  
Neogloboquadrina Dutertrei

A series of recent papers has called for multiple radiocarbon dates on planktic foraminifera to assess stratigraphic continuity in deep-sea sediment cores. This recommendation comes from observations of anomalous 14C dates in planktic foraminifera from the same stratigraphic level. Potential reasons include bioturbation, downslope transport, secondary calcification, carbonate dissolution, and differential preservation. In this study, paired 14C dates on dissolution-susceptible Globigerinoides ruber and dissolution-resistant Neogloboquadrina dutertrei are used to evaluate a Gulf of Mexico sediment core. Fourteen of 15 pairs (between 8815 and 12,995 uncorrected 14C yr BP) yield concordant uncorrected 14C ages (mean difference −2 ± 75 yr), attesting to continuous deposition at high accumulation rates (>35 cm/kyr). For 1 pair, N. dutertrei is nearly 1000 yr younger, which is difficult to explain by any combination of dissolution and bioturbation or downslope transport, given the excellent carbonate preservation and persistent laminations. The concordant ages underscore the utility of paired 14C dates in planktic foraminifera as a means of assessing stratigraphic continuity in deep-sea sediment sequences.

scholarly journals Texas A&M University Radiocarbon Dates II

Radiocarbon ◽  
1972 ◽  
Vol 14 (2) ◽  
pp. 452-455 ◽  
Author(s):  
T. D. Mathews ◽  
A. D. Fredericks ◽  
W. M. Sackett
Keyword(s):  
Organic Carbon ◽  
Gulf Of Mexico ◽  
Inorganic Carbon ◽  
Experimental Methods ◽  
Radiocarbon Dates ◽  
Seawater Samples

The radiocarbon laboratory in the Oceanography Department at Texas A&M University was established primarily for the examination of seawater samples, although other types of samples have been run. Emphasis has been placed on seawater samples of the Gulf of Mexico and adjacent areas. Most of the samples examined have been inorganic carbon, but some organic-carbon samples are being run, mainly wood and charcoal whose ages have been determined previously. More samples of known age will be run as a further check on the reliability of experimental methods and procedures.

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