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  • 1
    Call number: S 90.0066(129)
    In: Geologisches Jahrbuch
    Type of Medium: Series available for loan
    Pages: 192 S. + 1 Kt.-Beil.
    Series Statement: Geologisches Jahrbuch : Reihe A 129
    Language: German
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 2
    Publication Date: 2019-03-14
    Description: Holocene fringing reef development around Bora Bora is controlled by variations in accommodation space (as a function of sea-level and antecedent topography) and exposure to waves and currents. Subsidence ranged from 0 to 0·11 m kyr−1, and did not create significant accommodation space. A windward fringing reef started to grow 8·7 kyr bp, retrograded towards the coast over a Pleistocene fringing reef until ca 6·0 kyr bp, and then prograded towards the lagoon after sea-level had reached its present level. The retrograding portion of the reef is dominated by corals, calcareous algae and microbialite frameworks; the prograding portion is largely detrital. The reef is up to 13·5 m thick and accreted vertically with an average rate of 3·12 m kyr−1. Lateral growth amounts to 13·3 m kyr−1. Reef corals are dominated by an inner Pocillopora assemblage and an outer Acropora assemblage. Both assemblages comprise thick crusts of coralline algae. Palaeobathymetry suggests deposition in 0 to 10 m depth. An underlying Pleistocene fringing reef formed during the sea-level highstand of Marine Isotope Stage 5e, and is also characterized by the occurrence of corals, coralline algal crusts and microbialites. A previously investigated, leeward fringing reef started to form contemporaneously (8·78 kyr bp), but is thicker (up to 20 m) and solely prograded throughout the Holocene. A shallow Pocillopora assemblage and a deeper water Montipora assemblage were identified, but detrital facies dominate. At the Holocene reef base, only basalt was recovered. The Holocene windward–leeward differences are a consequence of less accommodation space on the eastern island side that eventually led to a more complex reef architecture. As a result of higher rates of exposure and flushing, the reef framework on the windward island side is more abundant and experienced stronger cementation. In the Pleistocene, the environmental conditions on the leeward island side were presumably unfavourable for fringing reef growth.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 17 (1998), S. 214-214 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
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  • 4
  • 5
    Publication Date: 2018-10-29
    Type: Dataset
    Format: text/tab-separated-values, 476 data points
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  • 6
    Publication Date: 2018-10-29
    Type: Dataset
    Format: text/tab-separated-values, 1920 data points
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  • 7
  • 8
    Publication Date: 2019-02-01
    Description: Highlights • First systematic description of Pleistocene facies of the Maldives reveals shallow-water deposits • Only U-series ages from Pleistocene deposits of the Maldives (MIS 5e) • Geochronology and paleo-bathymetric analyses allow estimation of late Quaternary subsidence of this major carbonate platform location to 0.09 - 0.16 m/kyr To date, there is hardly any knowledge of facies and age of Pleistocene reef limestone in the Maldives. Likewise, there are no robust estimates of Quaternary subsidence in this major shallow-water carbonate platform and reef area. In a core recovered on the windward margin of Rasdhoo Atoll in the central part of the archipelago, Pleistocene coralgal grainstone facies belonging to marine isotope stage (MIS) 5e were recovered underlying a Holocene reef succession, 14.5 m below modern sea level. Based on the occurrence of shallow-water stony corals such as Isopora palifera and possibly Acropora gr. robusta, high-energy coralline algae including Porolithon onkodes, in part associated with vermetids, and grain-supported limestone texture, the paleoenvironment is interpreted as a shallow back reef area with a paleo-waterdepth of 〈10 m. Based on a reliable U-series age from a Pleistocene acroporid coral of 136.9 kyr BP and assuming a + 7.5 m higher-than-present peak sea level during MIS 5e, late Quaternary subsidence is estimated to 0.09 m/kyr (minimum)–0.16 m/kyr (maximum value). A sea level of +2.5 m during the early MIS 5e would reduce the rates to 0.05 m/kyr (minimum)–0.12 m/kyr (maximum). These numbers are significant for reconstructions of depositional environments of this major carbonate platform area in the Quaternary. The subsidence estimates are not as crucial for historical reconstruction of relative sea level and for predictions of the near future in this low-lying archipelago, because they will add only a minor portion to the predicted rates of 21st century sea-level rise.
    Type: Article , PeerReviewed
    Format: text
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  • 9
    Publication Date: 2018-09-10
    Description: The detailed Holocene inundation history of the Bermuda North Lagoon may be used as model for transgressive and highstand sequences in carbonate platforms. Sedimentation and facies development were controlled largely by sea‐level rise and antecedent topography. Four late Pleistocene to Holocene sequences may be identified in North Lagoon based on a combined analysis of 200 km shallow reflection seismics and 39 cores including 29 radiometric and U/Th‐ages. The sequences were deposited during sea‐level highstands and are separated by subaerial exposure horizons that formed during sea‐level lowstands. Sequence 1 (inferred MIS 7) consists of well‐cemented carbonate sands. Sequence 2 (MIS 5) is up to 20 m thick and consists of well‐sorted, inter‐reefal sands and reef sediments with mound‐like structures. Sequence 3 (inferred MIS 3) is up to ca 6 m thick and accumulated in topographic lows of the underlying sequences some 20 m below modern sea‐level. Sequence 4 (MIS 1, Holocene) includes lagoonal sediments up to 10 m thick, and reefs that accumulated on topographic highs of the MIS 5 sequences. Holocene sediments in topographic lows include peat, peaty sediment, freshwater mud, restricted marine carbonates, and open lagoonal carbonate sediments deposited in seagrass beds, shallow water, and deeper lagoon areas. Upward fining is an expression of deepening and the development of a reef‐protected lagoon environment. Holocene sedimentation on topographic highs usually lacks freshwater and transitional facies and starts with shallow marine mollusc shell accumulations overlain by carbonate sediments that show fining upward. Packstone (68%), wackestone (22%), grainstone (9%) and mudstone (1%) textures occur in cores, with Halimeda, molluscs, coralline algae and foraminifera being the most common constituent particles; coral fragments are rare. During the Holocene, an estimated volume of 1 km3 of carbonate sediments was deposited in North Lagoon. Average sedimentation rates are estimated to be 0.32 m/kyr.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 10
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    Elsevier
    In:  Marine Micropaleontology, 86/87 . pp. 59-75.
    Publication Date: 2017-06-21
    Description: Tropical coral reefs are among the most diverse marine ecosystems. In order to better understand temporal and spatial variation in late Quaternary biodiversity, foraminiferal faunas of two fossil, raised reef terraces at the southern Sinai Peninsula were studied and compared to modern coral reef faunas. Eleven U-series dates of shell fragments of the giant clam Tridacna sp. indicates deposition largely during marine isotope stage 5 (MIS 5), 77–129 kyr BP, for the two raised terraces. In these terraces, Amphistegina (A. lessonii and A. lobifera) dominates the five fossil foraminiferal associations. The fossil reef-flat association 1 has common Gypsina plana, Homotrema rubra and Acervulina spp., and fossil reef-flat association 2 consists of Amphistegina spp. Of the three fossil fore-reef associations, one has abundant porcelaneous taxa including Sorites, Amphisorus, Peneroplis and Borelis, one has a mix of porcelaneous taxa and attached-arborescent taxa (Homotrema and Placopsilina) and one has abundant attached and arborescent taxa (Miniacina, Gypsina, Acervulina and Planogypsina). The modern fringing reef is dominated by porcelaneous foraminifera, and three modern associations are identified. These include a lagoonal association with abundant Peneroplis pertusus, a reef-flat association dominated by Sorites orbiculus and a fore-reef association with porcelaneous taxa plus common H. rubra, Amphistegina lessonii and A. lobifera. Based on our data and including additional published information on regional biodiversity it appears that during MIS 5 foraminiferal biodiversity was higher and community structure was different than within the modern reefs. These data and regional paleo-climate patterns indicate that oceanographic conditions in the Red Sea were probably closer to normal marine conditions during the last interglacial than they are today.
    Type: Article , PeerReviewed
    Format: text
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