Calcareous dinoflagellate cysts from the Pleistocene (Marine Isotope Stage 31) of the Ross Sea, Antarctica

2011 ◽  
Vol 23 (6) ◽  
pp. 597-604 ◽  
Author(s):  
Michael Streng ◽  
Oliver Esper ◽  
Jutta Wollenburg
Keyword(s):  
High Latitude ◽  
Ross Sea ◽  
Drill Core ◽  
Dinoflagellate Cysts ◽  
Late Neogene ◽  
Resting Cysts ◽  
Common Group ◽  
Palaeoenvironmental Reconstructions ◽  
New Form ◽  
Calcareous Dinoflagellate Cysts

AbstractFollowing a report of supposed fragments of calcareous dinoflagellate cysts from a Pleistocene drill core (CRP-1) recovered in the Ross Sea, Antarctica, sediments of the same core were re-investigated for their microfossil content. Besides common foraminifera and other microfossils, rare complete cysts of calcareous dinoflagellates were found. All cysts belong to the species Caracomia arctica (Gilbert & Clark, 1983) Streng, Hildebrand-Habel & Willems, 2002, a taxon characteristic of late Neogene high latitude, coldwater environments. Two morphotypes can be distinguished, C. arctica f. arctica and C. arctica f. rossensis, of which the latter is described as a new form. The presence of C. arctica strengthens diatom-based palaeoenvironmental reconstructions of periodical sea ice-free conditions at the time of deposition. Accordingly, cysts of C. arctica are interpreted as resting cysts that allow survival during harsh intervals of the high latitude environment. Previously reported calcareous dinoflagellates cyst fragments from these sediments are re-interpreted as test fragments of bilamellar foraminifera, which represent the most common group of foraminifers in the sediments.

scholarly journals HORIZONTAL DISTRIBUTION OF DINOFLAGELLATE CYSTS IN SURFACE SEDIMENTS OF JAKARTA BAY: SOME PRELIMINARY RESULTS

2008 ◽  
Vol 33 (1) ◽  
pp. 81-86
Author(s):  
Boy Rahardjo Sidharta ◽  
M. G. Lily Panggabean ◽  
Koichiro Mizushima
Keyword(s):  
Surface Sediments ◽  
Algal Bloom ◽  
Harmful Algal Bloom ◽  
Horizontal Distribution ◽  
Species Number ◽  
Dinoflagellate Cysts ◽  
Dinoflagellate Cyst ◽  
Sampling Locations ◽  
Resting Cysts ◽  
Unique Species

Ten surface sediment samples were collected from Jakarta Bay to study the horizontal distribution of dinoflagellate resting cysts in this area. Overall results had shown unique species composition and diversity of dinoflagellate cyst assemblages. However, dinoflagellate cysts found in this preliminary research were sparse and relatively low in term of species number and concentrations. Twenty cyst morphophites were identified in this research, within which ten cysts belong to autotrophic and another ten belong to heterotrophic species. Protoperidinium cysts were the most diversified group, predominating in almost the sampling locations. The cysts identified were generally characterized by species belonged to three orders namely Gonyaulacales, Gymnodiniales, and Peridiniales. Only one dinoflagellate cyst found that was belonged to the toxic and harmful algal bloom (HAB) member species, i.e. Gymnodinium catenatum.

scholarly journals Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

2016 ◽  
Vol 113 (13) ◽  
pp. 3453-3458 ◽  
Author(s):  
Richard Levy ◽  
David Harwood ◽  
Fabio Florindo ◽  
Francesca Sangiorgi ◽  
Robert Tripati ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Ross Sea ◽  
Ice Sheet ◽  
Sedimentary Facies ◽  
Time Interval ◽  
Drill Core ◽  
Antarctic Ice Sheet ◽  
Air Temperatures ◽  
Ice Sheet Modeling ◽  
The Antarctic

Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23–14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3–4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (∼280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (∼500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

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