DOI: 10.1016/j.palaeo.2015.03.045
论文题名: Effects of oceanic circulation and volcanic ash-fall on calcite dissolution in bathyal sediments from the SW Pacific Ocean over the last 550ka
作者: Cobianchi M. ; Mancin N. ; Lupi C. ; Bordiga M. ; Bostock H.C.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 429 起始页码: 72
结束页码: 82
语种: 英语
英文关键词: Carbonate dissolution
; Fragmentation index
; Late Pleistocene
; Nannofossil Dissolution Index
; SW Pacific
英文摘要: The effects on calcite dissolution of both oceanic circulation and volcanic ash-fall were evaluated in lower bathyal sediments over the last 550ka record from core MD 97-2114, recovered on the northern slope (depth of 1936m, in the Pacific Deep Water, PDW) of the Chatham Rise (east of New Zealand, SW Pacific Ocean). This area has been impacted by changes in glacial/interglacial circulation and ocean chemistry as well as by the explosive volcanic activity of the Taupo Volcanic Zone. Several micro-paleontological dissolution proxies, based on planktonic foraminifera and calcareous nannofossils, were analysed in order to evaluate the calcite dissolution of the deep-sea sediments. These were compared with a couple of proxies of primary productivity (benthic foraminiferal epifaunal/infaunal ratio and δ13Cbenthic foraminifera ) and the abundance of volcanic glass. The dissolution proxy data from MD 97-2114 were compared with two nearby ODP sites, ODP 1123 (3290m deep, bathed by the lower Circumpolar Deep Water, LCDW) and ODP 1125 (1365m deep, bathed by the Antarctic Intermediate Water, AAIW).The results suggest: (1) the calcite dissolution/preservation cycles at all three core sites show Glacial-Interglacial (G-I) periodicities that match the previously described "Pacific-style" CaCO3 cycles; (2) several short-term dissolution events do not follow this general scheme and occur following tephra deposition. The dissolution related to the tephra deposition seems to have mostly affected calcareous nannofossils, thus we hypothesise that the ash-fall induced a temporary reduction of the surface water pH (below 7.8), which affected the coccolithophores that inhabit the surface waters. (3) Other short-term dissolution events (1000years) are unrelated to tephra deposition and are possibly driven by the slowing of deep-sea circulation and a reduced Deep Western Boundary Current (DWBC). This lead to the dominance of older, more corrosive Pacific Deep Water (PDW) flowing in to the region, resulting in coeval dissolution episodes at all three core sites (depth range from 1365 to 3290m). © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68932
Appears in Collections: 过去全球变化的重建
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作者单位: Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Via Ferrata 1, Pavia, Italy; Department of Earth Sciences, Uppsala Universitet, Villavägen 16, Uppsala, Sweden; National Institute of Water and Atmospheric Research, Greta Point, Wellington, New Zealand
Recommended Citation:
Cobianchi M.,Mancin N.,Lupi C.,et al. Effects of oceanic circulation and volcanic ash-fall on calcite dissolution in bathyal sediments from the SW Pacific Ocean over the last 550ka[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,429