Seasonal evolution of oxygen isotope-salinity relationships in high-latitude surface waters

1993 ◽  
Vol 98 (C8) ◽  
pp. 14589 ◽  
Author(s):  
Peter M. Strain ◽  
Francis C. Tan
Keyword(s):  
Oxygen Isotope ◽  
Surface Waters ◽  
High Latitude ◽  
Seasonal Evolution ◽  
Evolution Of Oxygen

scholarly journals Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the Southwest Pacific

2015 ◽  
Vol 11 (4) ◽  
pp. 2977-3018 ◽  
Author(s):  
K. M. Pascher ◽  
C. J. Hollis ◽  
S. M. Bohaty ◽  
G. Cortese ◽  
R. M. McKay
Keyword(s):  
Oxygen Isotope ◽  
High Latitude ◽  
Large Scale ◽  
Middle Eocene ◽  
Late Eocene ◽  
Climate History ◽  
Southwest Pacific ◽  
Early Oligocene ◽  
Radiolarian Assemblages

Abstract. The Eocene was characterised by "greenhouse" climate conditions that were gradually terminated by a long-term cooling trend through the middle and late Eocene. This long-term trend was determined by several large-scale climate perturbations that culminated in a shift to "ice-house" climates at the Eocene–Oligocene Transition. Geochemical and micropaleontological proxies suggest that tropical-to-subtropical sea-surface temperatures persisted into the late Eocene in the high-latitude Southwest Pacific Ocean. Here, we present radiolarian microfossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) Sites 277, 280, 281 and 283 from the middle Eocene to early Oligocene (~ 40–33 Ma) to identify oceanographic changes in the Southwest Pacific across this major transition in Earth's climate history. The Middle Eocene Climatic Optimum at ~ 40 Ma is characterised by a negative shift in foraminiferal oxygen isotope values and a radiolarian assemblage consisting of about 5 % of low latitude taxa Amphicraspedum prolixum group and Amphymenium murrayanum. In the early late Eocene at ~ 37 Ma, a positive oxygen isotope shift can be correlated to the Priabonian Oxygen Isotope Maximum (PrOM) event – a short-lived cooling event recognized throughout the Southern Ocean. Radiolarian abundance, diversity, and preservation increase during the middle of this event at Site 277 at the same time as diatoms. The PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. These high-latitude taxa also increase in abundance during the late Eocene and early Oligocene at DSDP Sites 280, 281 and 283 and are associated with very high diatom abundance. We therefore infer a~northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau towards the end of the late Eocene. In the early Oligocene (~ 33 Ma) there is an overall decrease in radiolarian abundance and diversity at Site 277, and diatoms are absent. These data indicate that, once the Tasman Gateway was fully open in the early Oligocene, a frontal system similar to the present day was established, with nutrient-depleted subantarctic waters bathing the area around DSDP Site 277, resulting in a more oligotrophic siliceous plankton assemblage.

Heinrich event 4 and Dansgaard/Oeschger events 5–10 recorded by high-resolution speleothem oxygen isotope data from central China

2014 ◽  
Vol 82 (2) ◽  
pp. 394-404 ◽  
Author(s):  
Houyun Zhou ◽  
Jian-xin Zhao ◽  
Yuexing Feng ◽  
Qiong Chen ◽  
Xiaojian Mi ◽  
...  
Keyword(s):  
High Resolution ◽  
Oxygen Isotope ◽  
High Precision ◽  
High Latitude ◽  
Southwest China ◽  
Asian Summer Monsoon ◽  
Central China ◽  
Temperature Changes ◽  
Heinrich Event ◽  
Asian Summer

AbstractA 50-yr resolution reconstruction of climate and environment variability during the period 43–14 ka was developed using 26 high-precision U/Th dates and 390 oxygen isotope (δ18O) data of a stalagmite (SJ1) collected from Songjia Cave in central China, which is close to the northwestern boundary of the Asian summer monsoon (ASM). The δ18O record in SJ1 displays significant millennial-scale changes that correlate well in timing and duration with Dansgaard/Oeschger (D/O) events 5–10 and Heinrich event 4 (H4) identified in high-latitude regions of the Northern Hemisphere. Four 230Th dates constrain the H4 event precisely to the period of 39.7 to 38.3 ka. Notable centennial variations of the ASM activity could be observed within the H4 event. The magnitude and duration of D/O event 4.1 recorded in SJ1 are similar to those archived in east China but different from those documented in southwest China, suggesting that the manifestation of this event may be regionally different. The timing, duration and structure of D/O events 5–10 and Heinrich event 4 suggest that temperature changes in both hemispheres have exerted significant influences on the ASM variations in central China.

Strontium and Oxygen Isotope Profiles of Sequentially Sampled Modern Bison (Bison bison bison) Teeth from Interior Alaska as Proxies of Seasonal Mobility

ARCTIC ◽  
2018 ◽  
Vol 71 (2) ◽  
Author(s):  
Crystal L. Glassburn ◽  
Ben A. Potter ◽  
Jamie L. Clark ◽  
Joshua D. Reuther ◽  
Darren L. Bruning ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
High Latitude ◽  
Animal Movement ◽  
Movement Patterns ◽  
Isotope Ratios ◽  
Bison Bison ◽  
Mobility Patterns ◽  
Second Molar ◽  
Interior Alaska ◽  
Isotopic Analyses

Studies addressing prehistoric mobility in animals typically use isotopic analyses of sequentially formed tissues, such as the growth layers in teeth, to infer physical movement on the landscape. Strontium isotope ratios (87Sr/86Sr values), which vary geographically, are particularly useful for this purpose, especially when paired with stable oxygen isotope ratios (δ18O), which vary seasonally. Together, these two isotope systems can provide information about past animal movement patterns on a seasonal scale. However, while many studies have used 87Sr/86Sr and δ18O values from analyses of sequentially formed tissues for this purpose, there have been limited analyses on modern animals of known movement patterns across high-latitude regions. In this pilot study, we sequentially sampled and analyzed one second molar (M2) and two third molars (M3) from two bison (Bison bison bison) from the Delta bison herd, which resides in interior Alaska and has known and documented seasonal mobility patterns. The resulting 87Sr/86Sr values from the teeth were compared to a high-resolution 87Sr/86Sr isoscape for the region and were paired with δ18O analyses to determine whether the seasonal 87Sr/86Sr values matched the predicted values for each of the seasonal bison habitat areas. The results indicate that the 87Sr/86Sr and δ18O values reliably reflected the known seasonal mobility patterns of bison and suggest that this approach could be used to investigate the mobility patterns of prehistoric bison in Alaska and surrounding high-latitude regions.

Timescales for the evolution of oxygen isotope compositions in the solar nebula

2009 ◽  
Vol 73 (17) ◽  
pp. 4998-5017 ◽  
Author(s):  
J.R. Lyons ◽  
E.A. Bergin ◽  
F.J. Ciesla ◽  
A.M. Davis ◽  
S.J. Desch ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Solar Nebula ◽  
Evolution Of Oxygen

scholarly journals Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation

2019 ◽  
Author(s):  
Liudmila S. Shirokova ◽  
Artem V. Chupakov ◽  
Svetlana A. Zabelina ◽  
Natalia V. Neverova ◽  
Dahedrey Payandi-Rolland ◽  
...  
Keyword(s):  
Organic Matter ◽  
High Temperature ◽  
Dissolved Organic Matter ◽  
Water Column ◽  
Surface Waters ◽  
High Latitude ◽  
Peat Bogs ◽  
Photo Degradation ◽  
Thermokarst Lake ◽  
C Cycle

Abstract. Bio- and photo-degradation of dissolved organic matter (DOM) is identified as dominant vector of C cycle in boreal and high-latitude surface waters. In contrast to large number of studies of humic waters from permafrost-free regions and oligotrophic waters from permafrost-bearing regions, the bio- and photo-lability of DOM from humic surface waters of permafrost-bearing regions has not been thoroughly evaluated. Following standardized methods, we measured biodegradation (low, intermediate, high temperature) and photodegradation (one intermediate temperature) of DOM in surface waters along the hydrological continuum (depression → stream → thermokarst lake → river Pechora) within a European Russian frozen peatland. In all systems, there was no measurable (≥ 10 %) bio- or photodegradation of DOM over 1 month of incubation. It is possible that the main cause of the lack of degradation is the dominance of allochthonous refractory (soil, peat) DOM in all studied waters. Yet, all surface waters were supersaturated with CO2. Thus, this study suggest that, rather than bio- and photo-degradation of DOM in the water column, other factors such as peat porewater DOM processing and respiration of sediments are the main drivers of elevated pCO2 and emission in humic boreal waters of frozen peat bogs.

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