Helium isotope ratios and sedimentation rate models of ODP holes


Autoria(s): Farley, Kenneth A; Eltgroth, Selene F
Cobertura

MEDIAN LATITUDE: -17.553960 * MEDIAN LONGITUDE: -37.576465 * SOUTH-BOUND LATITUDE: -65.161000 * WEST-BOUND LONGITUDE: -76.357830 * NORTH-BOUND LATITUDE: 30.053080 * EAST-BOUND LONGITUDE: 1.204900 * DATE/TIME START: 1987-01-20T03:15:00 * DATE/TIME END: 1997-01-27T02:00:00

Data(s)

06/07/2003

Resumo

A continuous age model for the brief climate excursion at the Paleocene-Eocene boundary has been constructed by assuming a constant flux of extraterrestrial 3He (3He[ET]) to the seafloor. 3He[ET] measurements from ODP Site 690 provide quantitative evidence for the rapid onset (<few kyr) and short duration (<120 kyr) of global warming and of the associated disturbance to the Earth's surficial carbon budget at this time. These observations support astronomically calibrated age models indicating extremely rapid release of isotopically light carbon, possibly from seafloor methane hydrate, as the proximal cause of the event. However, the 3He[ET] technique indicates a previously unrecognized and extreme increase in sedimentation rate coincident with the return of climate proxies to pre-event values. The 3He[ET]-based age model thus suggests a far more rapid recovery from the climatic perturbation than previously proposed or predicted on the basis of the modern carbon cycle, and so may indicate additional or accelerated mechanisms of carbon removal from the ocean-atmosphere system during this period. 3He[ET] was also measured at ODP Site 1051 to test the validity of the Site 690 chronology. Comparison of these data sets seems to require removal of several tens of kyr of sediment within the climatic excursion at Site 1051, an observation consistent with sediment structures and previous age modeling efforts. The Site 1051 age model shows a ~30 kyr period in which climate proxies return toward pre-event values, after which they remain invariant for ~80 kyr. If this rise represents the recovery interval identified at Site 690, then the 3HeET-based age models of the two sites are in good agreement. However, alternative interpretations are possible, and work on less disrupted sites is required to evaluate the reliability of the proposed new chronology of the climate excursion. Regardless of these details, this work shows that the 3HeET technique can provide useful independent evidence for the development and testing of astronomically calibrated age models.

Formato

application/zip, 2 datasets

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.723912

doi:10.1594/PANGAEA.723912

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Farley, Kenneth A; Eltgroth, Selene F (2003): An alternative age model for the Paleocene-Eocene thermal maximum using extraterrestrial 3He. Earth and Planetary Science Letters, 208(3-4), 135-148, doi:10.1016/S0012-821X(03)00017-7

Palavras-Chave #113-690B; 171-1051B; 2 sigma, propagates uncertainty in 3He flux only; assumes uncertainty in 3He extraterrestrial fraction (due to terrestrial 3He/4He endmember; 2 sigma, Propagates uncertainty in 3He flux only; assumes uncertainty in 3He extraterrestrial fraction (due to terrestrial 3He/4He endmember ratio uncertainty) cancels; 3He; 3He/4He; 3He std dev; Age, maximum/old; Age, minimum/young; Age, relative; Age max; Age min; Age rel; assumes an extraterrestrial 3He flux of 0.765 pcc/cm**2/kyr and the listed dry dbulk density; Assumes a uniform dry bulk density of 1.44 g/cm**3 and an extraterrestrial 3He flux of 0.25 pcc/cm**2/kyr; Blake Nose, North Atlantic Ocean; Carb; Carbonates; computed from GRAPE wet bulk density and the model of Herbert and Mayer 1991; DBD; Density, dry bulk; Depth; Depth, composite mean; DEPTH, sediment/rock; Depth c mean; DRILL; Drilling/drill rig; Duration; Duration, maximum; Duration, minimum; Duration max; Duration min; error based on range of terrestrial endmember ratios; extraterrestrial; Helium-3; Helium-3, standard deviation; Helium-3/Helium-4; is depositional interval between sample N and and sample N+1 divided by mean LSR of N and N+1; is sum of durations of each interval, with base of CIE (170.65 mbsf) defined as zero; Joides Resolution; Label; Leg113; Leg171B; mean depth (mbsf); Ocean Drilling Program; ODP; ODP sample designation; Sample code/label; Sedimentation rate; Sedimentation rate, standard deviation; Sediment thickness; Sed rate; Sed rate std dev; Sed thick; South Atlantic Ocean; typical uncertainty on these values is < 10% (2 sigma); use the duration extrema in the previous columns; use the sedimentation rate extrema in the previous columns
Tipo

Dataset