非表示:
キーワード:
WESTERN MEDITERRANEAN SEA; LAST GLACIAL MAXIMUM; BENTHIC FORAMINIFERA; LATE QUATERNARY; SAPROPEL FORMATION; AEGEAN SEA; CLIMATE VARIABILITY;
BALEARIC-ISLANDS; PALYNOLOGICAL EVIDENCE; ADRIATIC SEAwestern Mediterranean Sea; stable oxygen and carbon isotopes; benthic
and planktonic foraminifera; Holocene; Mallorca shelf; ecosystem changes;
要旨:
Benthic foraminiferal data as well as stable oxygen and carbon isotope records of different planktonic and benthic foraminifera from a shelf sediment core off southwest Mallorca document major sedimentological, hydrological and trophic changes during the Holocene. The Holocene relative sea-level rise resulted in the progradation of different sediment facies types characterized by specific benthic foraminiferal assemblages. This succession reflects the evolution from an unstable shelf ecosystem with high-energy conditions at the sea-floor in the earlier Holocene to a more stable shelf ecosystem in the middle and late Holocene. Between approximately 10.3 and 5.5 kyr BP, low delta C-13 values of the surface dweller Globigerinoides ruber (white) and high difference in delta C-13 values between the epifaunal Cibicides lobatulus and the infaunal Bulimina aculeata document enhanced input of nutrients in surface waters and high remineralization rates at the sea floor. The trophic change is associated with a change in sediment facies and can be attributed to higher precipitation and consequently, higher nutrient supply via riverine runoff from the island, mainly during the late summer/early fall season. This early Holocene humid interval is nearly contemporaneous to the formation of sapropel Si in the eastern Mediterranean Sea and the African Humid Period. (c) 2012 Elsevier B.V. All rights reserved.
