Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water dept...Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp. , Bathysiphon flavidus, corresponds to strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region.展开更多
The study is based on stable carbon isotopic measurements of 112 foraminiferal samples from surface sediments at 40 sites in the South China Sea (SCS). δ 13C of foraminifers and ?δ C between planktonic and benthic 1...The study is based on stable carbon isotopic measurements of 112 foraminiferal samples from surface sediments at 40 sites in the South China Sea (SCS). δ 13C of foraminifers and ?δ C between planktonic and benthic 13 foraminiferal species exhibit a low value area at the north- eastern and southern ends of the SCS. It is correlated with the nutrient distributional pattern in the SCS and circumja- cent area, the influence of the northeastern and southwestern monsoons on water flow and water chemistry in the SCS. The monsoons have not only brought nutrients to the upper part of the sea but also disturbed water and decreased dif- ference between the surface and bottom water. Its influence is most obvious at both ends, which resulted in the low value areas in δ 13C and ?δ 13C at the ends. The distributional pat- tern of the stable carbon isotope in the SCS is a reflection of the East Asian monsoons.展开更多
基金This research was jointly supported by the National Natural Science Foundation of China under contract Nos 49736210,40176019 and 40106006,and the Post-doctoral Fund of Ocean University of Qingdao,China.
文摘Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp. , Bathysiphon flavidus, corresponds to strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region.
基金This work was supported by the National Key Basic Research Special Foundation Project of China(Grant No.2000078502)the National Natural Science Foundation of China(Grant Nos.40321603,40331002,40125015 and 40376019).
文摘The study is based on stable carbon isotopic measurements of 112 foraminiferal samples from surface sediments at 40 sites in the South China Sea (SCS). δ 13C of foraminifers and ?δ C between planktonic and benthic 13 foraminiferal species exhibit a low value area at the north- eastern and southern ends of the SCS. It is correlated with the nutrient distributional pattern in the SCS and circumja- cent area, the influence of the northeastern and southwestern monsoons on water flow and water chemistry in the SCS. The monsoons have not only brought nutrients to the upper part of the sea but also disturbed water and decreased dif- ference between the surface and bottom water. Its influence is most obvious at both ends, which resulted in the low value areas in δ 13C and ?δ 13C at the ends. The distributional pat- tern of the stable carbon isotope in the SCS is a reflection of the East Asian monsoons.
