Spiniferites Mirabilis Research Articles

Recent Dinoflagellate Cysts from Estuaries on the Central Coast of New South Wales, Australia

Nineteen species of dinoflagellate cysts and four species of acritarchs have been recognized in surface sediments from estuaries on the N.S.W. central coast. Prominent species include Operculodinium centrocarpum (Deflandre & Cookson) Wall 1967, Lingulodinium hemicystum n. sp., Spiniferites bulloideus (Deflandre and Cookson) Sarjeant 1970, Spiniferites mirabilis (Rossignol) Sarjeant 1970, Spiniferites ramosus (Ehrenberg) Loeblich & Loeblich 1966 and Protoperidinium spp. Cyst assemblages within an estuary are more similar to each other than to assemblages from comparable environments but from different estuaries. Environmental changes within an estuary cause the cyst abundance to decrease without significantly altering the relative abundances. Lingulodinium hemicystum and Cobricosphaeridium giganteum are described as new species.

Distribution des kystes de dinoflagellés dans les sédiments pléistocènes de la marge guinéenne de l'afrique (Equamarge I, 1983)

In sediments from core KS 03 from the Guinean margin (west coast of Africa), it is possible to distinguish two groups of dinoflagellate cysts, serving as indicators of change of temperature: a group of warm to temperate species, including Impagidinium paradoxum, Impagidinium strialatum, Impagidinium aculeatum and Impagidinium patulum, and a group of cold to temperate species, including Operculodinium centrocarpum, Nematosphaeropsis labyrinthae and Spiniferites mirabilis. The ratio of the relative abundances of the two groups indicates the ecological nature of the water masses which have migrated in the north Atlantic during the Pleistocene. The curve of the ratio of warm-temperate species to cold-temperate species shows a high similarity to the δ 18O curve from the tests of benthic foraminifers. A high percentage of Operculodinium centracarpum among the cold temperate species reveals not only the presence of subpolar water masses, but also the importance of the North Atlantic current along the west coast of Africa. The reworked and transported species from the coastal zone give evidence of the characters of the Guinean littoral environment, this being determined by the moisture and the aridity of the climate. Lingulodinium machaerophorum grows in waters rich in nutrients, with normal salinity. Polysphaeridium zoharyi prefers highly saline waters and indicate the beginning of aridity. Operculodinium israelianum is abundant in restricted environments containing high percentages of organic matter. Core KS 03 corresponds to the interval of time between 800,000 and 122,000 yr B.P. During the glacial stages, stages 20 and 18, the water masses with planktonic assemblages of transitional-subtropical character, associated with Spiniferites mirabilis, come close to the Guinean coast, as during the last glacial stage, and produce an intense aridity on the continent. At that period the influence of subpolar water masses and of the North Atlantic current, characterised by Operculodinium centrocarpum, can be perceived on the west African margin. Aridity tends to regress. At the end of stage 16, the tropical water masses remained preponderant even during glacial stages. Restricted, humid environments with Operculodinium israelianum extended along the coast. After stage 11, transitional to subtropical waters extended down again along the African coast, but the glacial stages were less cold and less arid.

A deep 226Ra maximum in the northeast Pacific : CHUNG YU-CHIA, 1976. GEOSECS Publ., 70. Also in: Earth planet. Sci. Letts, 32 (2): 249–257

A high resolution micropalaeontological study of the core MD 04-2797 CQ recovered in the Sicilian–Tunisian Strait provides insights into the paleoclimatic history of the Mediterranean Sea at the transition between the western and eastern basin over the last 30 ka. Using the analysis of dinoflagellate cyst and planktonic foraminiferal assemblages, we reconstruct the paleoenvironmental changes that took place in this region. High abundances of cold temperate dinocyst species (Nematosphaeropsis labyrinthus, Spiniferites elongatus, Bitectatodinium tepikiense) and the polar planktonic foraminifera Neogloboquadrina pachyderma (left coiling) reveal three major cooling events synchronous with North Atlantic Henrich events 1 and 2 (H1 and H2) and the European and North Atlantic Younger Dryas event. During the Holocene, the presence of warm dinocyst species (Spiniferites mirabilis and Impagidinium aculeatum) and planktonic foraminifera (Globorotalia inflata and Globigerinoides ruber), reflects a significant increase of sea surface temperatures in the western Mediterranean basin, but a full warming was not recorded until 1500 years after the onset of the Holocene. Moreover, our results show that the Holocene was interrupted by at least four brief cooling events at ~ 9.2 ka, ~ 8 ka, ~ 7 ka and ~ 2.2 ka cal. BP, which may be correlated to climatic events recorded in Greenland ice cores and in the Atlantic Ocean.