DOI: 10.1016/j.palaeo.2013.02.005
论文题名: Stepwise post-glacial transgression in the RhÔne Delta area as revealed by high-resolution core data
作者: Amorosi A. ; Rossi V. ; Vella C.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 374 起始页码: 314
结束页码: 326
语种: 英语
英文关键词: Late Quaternary
; Millennial cycles
; RhÔne Delta
; Sea-level change
; Transgressive systems tract
英文摘要: Integrated sedimentological and micropalaeontological (benthic foraminifers and ostracods) analyses of two continuous cores (40. m and 50. m long, respectively) recovered in the lower delta plain of modern Petit RhÔne Delta, along with data from the previously studied Core SF, enable detailed reconstruction of the late Pleistocene-Holocene palaeoenvironmental evolution of the RhÔne Delta system. Through identification of nine microfossil assemblages and with the aid of 28 radiocarbon dates, a high-resolution picture of stratigraphic architecture is offered for the first time for the entire post-glacial succession. Above late Pleistocene fluvial-channel gravels, a retrograding pattern of swamp and estuarine/bay deposits (lower transgressive systems tract - TST) is overlain by vertically stacked, late transgressive nearshore deposits (upper TST). This succession reflects the progressive landward migration of the palaeoshoreline driven by the rapid post-glacial sea-level rise, which took place in the study area between ca. 12 and 7. cal ky BP. The following deceleration in sea-level rise (highstand phase) induced the onset of deltaic sedimentation, as evidenced by superposition of middle-late Holocene prodelta, delta-front and delta-plain deposits within the cored succession. At distal location the occurrence, within prodelta deposits, of a distinctive microfossil assemblage dominated by opportunistic benthic foraminifer Valvulineria bradyana marks the onset of the RhÔne Delta mud-belt around 4. cal ky BP. Identification and lateral tracking of six separate flooding surfaces within the TST enable the characterization of five short-term (millennial to sub millennial-scale) depositional cycles with distinctive transgressive-regressive internal architecture (T-R 1-5). The lower, transgressive portions of cycles 1-3 (11.8-9.8. cal ky BP) mark abrupt shifts from freshwater to increasingly mixed, brackish-marine environments under conditions of rapid sea-level rise. In contrast, the upper, 'regressive' portions represent the filling of newly formed accommodation space via extensive crevasse to bay-head delta processes. Cycles 4 and 5 (9.8-8.2. cal ky BP) and the uppermost transgressive deposit below the maximum flooding surface document three distinct landward shifts of the shoreline that took place under conditions of rapidly increasing sea-level rise. The vertical stacking of these millennial-scale cycles is interpreted to reflect the stratigraphic response to stepwise sea-level rise during the early Holocene. The youngest flooding surface may represent the sea-level signature of the 8.2. ka climate event. © 2013 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69809
Appears in Collections: 过去全球变化的重建
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作者单位: Dipartimento di Scienze Biologiche, Geologiche e Ambientali, University of Bologna, Via Zamboni 67, 40127 Bologna, Italy; Aix Marseille Université, CNRS, CEREGE UMR 7330, 13545 Aix en Provence, France
Recommended Citation:
Amorosi A.,Rossi V.,Vella C.. Stepwise post-glacial transgression in the RhÔne Delta area as revealed by high-resolution core data[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,374