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  • 11
    Publication Date: 2023-05-12
    Keywords: Age, 206Pb/238U Lead-Uranium; Age, 207Pb/206Pb Lead-Lead; Age, comment; Age, dated; Age, dated standard deviation; Color description; Crystallinity; Electron microprobe (EMP); Event label; Latitude of event; Longitude of event; ROCK; Rock sample; Rock type; Sample amount; Size; Sverdrupfjella, East Antarctica; Thorium/Uranium ratio; WBSV025; WBSV065; WBSV071; WBSV073; WBSV074; WBSV113; WBSV114; WBSV116
    Type: Dataset
    Format: text/tab-separated-values, 225 data points
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  • 12
    Publication Date: 2023-05-12
    Keywords: Aluminium; Aluminium (IV); Aluminium (VI); Aluminium oxide; Calcium; Calcium oxide; Chromium; Chromium(III) oxide; Electron microprobe (EMP); Elements, total; Event label; Fluorine; Grains; Iron 2+ and 3+; Iron oxide, FeO; Latitude of event; Longitude of event; Magnesium; Magnesium oxide; Manganese; Manganese oxide; Potassium; Potassium oxide; ROCK; Rock sample; Rock type; Silicon; Silicon dioxide; Sodium; Sodium oxide; Sum; Sverdrupfjella, East Antarctica; Titanium; Titanium dioxide; WBSV025; WBSV084; WBSV110
    Type: Dataset
    Format: text/tab-separated-values, 456 data points
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  • 13
    Publication Date: 2023-05-12
    Keywords: Aluminium; Aluminium oxide; Calcium; Calcium oxide; Chromium; Chromium(III) oxide; Electron microprobe (EMP); Elements, total; Event label; Grains; Iron 2+ and 3+; Iron oxide, FeO; Latitude of event; Longitude of event; Magnesium; Magnesium oxide; Manganese; Manganese oxide; Potassium; Potassium oxide; ROCK; Rock sample; Rock type; Silicon; Silicon dioxide; Sodium; Sodium oxide; Sum; Sverdrupfjella, East Antarctica; Titanium; Titanium dioxide; WBSV031; WBSV034; WBSV041; WBSV066; WBSV079
    Type: Dataset
    Format: text/tab-separated-values, 575 data points
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  • 14
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    PANGAEA
    In:  Supplement to: Board, W S; Frimmel, Hartwig E; Armstrong, Robert A (2005): Pan-African tectonism in the western Maud Belt: P-T-t path for high-grade gneisses in the H.U. Sverdrupfjella, East Antarctica. Journal of Petrology, 46(4), 671-699, https://doi.org/10.1093/petrology/egh093
    Publication Date: 2023-10-28
    Description: Extensive high-grade polydeformed metamorphic provinces surrounding Archaean cratonic nuclei in the East Antarctic Shield record two tectono-thermal episodes in late Mesoproterozoic and late Neoproterozoic-Cambrian times. In Western Dronning Maud Land, the high-grade Mesoproterozoic Maud Belt is juxtaposed against the Archaean Grunehogna Province and has traditionally been interpreted as a Grenvillian mobile belt that was thermally overprinted during the Early Palaeozoic. Integration of new U-Pb sensitive high-resolution ion microprobe and conventional single zircon and monazite age data, and Ar-Ar data on hornblende and biotite, with thermobarometric calculations on rocks from the H.U. Sverdrupfjella, northern Maud Belt, resulted in a more complex P-T-t evolution than previously assumed. A c. 540 Ma monazite, hosted by an upper ampibolite-facies mineral assemblage defining a regionally dominant top-to-NW shear fabric, provides strong evidence for the penetrative deformation in the area being of Pan-African age and not of Grenvillian age as previously reported. Relics of an eclogite-facies garnet-omphacite assemblage within strain-protected mafic boudins indicate that the peak metamorphic conditions recorded by most rocks in the area (T = 687-758°C, P = 9·4-11·3 kbar) were attained subsequent to decompression from P 〉 12·9 kbar. By analogy with limited U-Pb single zircon age data and on circumstantial textural grounds, this earlier eclogite-facies metamorphism is ascribed to subduction and accretion around 565 Ma. Post-peak metamorphic K-metasomatism under amphibolite-facies conditions is ascribed to the intrusion of post-orogenic granite at c. 480 Ma. The recognition of extensive Pan-African tectonism in the Maud Belt casts doubts on previous Rodinia reconstructions, in which this belt takes a pivotal position between East Antarctica, the Kalahari Craton and Laurentia. Evidence of late Mesoproterozoic high-grade metamorphism during the formation of the Maud Belt exists in the form of c. 1035 Ma zircon overgrowths that are probably related to relics of granulite-facies metamorphism recorded from other parts of the Maud Belt. The polymetamorphic rocks are largely derived from a c. 1140 Ma volcanic arc and 1072 ± 10 Ma granite.
    Keywords: Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; SPP1158
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 15
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    PANGAEA
    In:  Supplement to: Bisnath, Avinash; Frimmel, Hartwig E; Armstrong, Robert A; Board, W S (2006): Tectono-thermal evolution of the Maud Belt: New SHRIMP U–Pb zircon data from Gjelsvikfjella, Dronning Maud Land, East Antarctica. Precambrian Research, 150(1-2), 95-121, https://doi.org/10.1016/j.precamres.2006.06.009
    Publication Date: 2023-10-28
    Description: The Maud Belt in Dronning Maud Land (western East Antarctic Craton) preserves a high-grade polyphase tectono-thermal history with two orogenic episodes of Mesoproterozoic (1.2-1.0 Ga) and Neoproterozoic (0.6-0.5 Ga) age. New SHRIMP U-Pb zircon data from southern Gjelsvikfjella in the northeastern part of the belt make it possible to differentiate between a series of magmatic and metamorphic events. The oldest event recorded is the formation of an extensive 1140-1130 Ma volcanic arc. This was followed by 1104 ± 8 Ma granitoids that might represent, together with so far undated mafic dykes, part of a decompression melting-related bimodal suite that reflects the sub-continental Umkondo igneous event. The first high-grade metamorphism is constrained at 1070 Ma. The metamorphic age data are similar to those obtained from other parts of the Maud Belt, but also from the Namaqua-Natal Belt in South Africa, but the preceding arc formation was diachronous in the two belts. This indicates that the two belts did not form a continuous volcanic arc unit as suggested in previous models, but became connected only at the end of the Mesoproterozoic. Intense reworking during the Neoproterozoic, probably as a result of continent-continent collision between components of Gondwana, is indicated by ductile refliation, further high-grade metamorphic recrystallisation and metamorphic zircon overgrowths at approximately 530 Ma. This was followed by late- to post-tectonic magmatism, reflected by 500 Ma granite bodies and 490 Ma aplite dykes as well as a 480 Ma gabbro body.
    Keywords: Dronning Maud Land, Antarctica; Gjelsvikfjella; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; ROCK; Rock sample; SPP1158
    Type: Dataset
    Format: application/zip, 8 datasets
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  • 16
    Publication Date: 2023-10-14
    Description: MedFlux sampling was carried out at the French JGOFS DYFAMED (DYnamique des Flux Atmospheriques en MEDiterranee) site in the Ligurian Sea (northwestern Mediterranean), 52km off Nice (431200N, 71400E) in 2300m water depth. In 2003, a mooring with sediment trap arrays was deployed 6 March (day of year, DOY 65) and recovered 6 May (DOY 126); this trap deployment will be referred to as Period 1 (P1). The array was redeployed a week later on 14 May (DOY 134) and recovered again on 30 June (DOY 181); this trap deployment will be referred to as Period 2 (P2). Indented-rotating sphere (IRS) valve traps were fitted with TS carousels to determine temporal variability of particulate matter flux. TS traps were fitted with ''dimpled'' spheres. Vertical flux at 200m depth is considered to be equivalent to new or export production, and traps sampled at 238 and 117m during P1 and P2, respectively. We also collected TS material at 711m during P1 and at 1918m during P2. Upon recovery, samples were split using a McLaneTM WSD splitter to allow multiple chemical analyses. Here we report 2003 data on TS particulate mass, and the contributions of organic carbon (OC), opal, lithogenic material and calcium carbonate to mass. In 2005, traps were deployed as described above for 55 d during a single period from 4 March (DOY 63) to 1 May (DOY 121). TS traps were fitted with ''dimpled'' spheres. TS particulate matter was collected from 313 to 924 m.
    Keywords: Calcium carbonate, flux; Carbon, inorganic, particulate, flux per day; Carbon, organic, particulate, flux; DATE/TIME; Date/time end; DEPTH, water; Duration, number of days; Event label; Flux of total mass; Lithogenic, flux; MedFlux; MedFlux_2003_P1_SV; MedFlux_2003_P1_TS; MedFlux_2003_P2_TS; MedFlux_2005_SV; MedFlux_2005_TS; Nitrogen, organic, particulate, flux per day; Sample code/label; Silica, particulate, flux per day; Trap, sediment; TRAPS
    Type: Dataset
    Format: text/tab-separated-values, 839 data points
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  • 17
    Publication Date: 2022-05-25
    Description: Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 76 (2009): 113-133, doi:10.1016/j.jmarsys.2008.05.010.
    Description: Depth-integrated primary productivity (PP) estimates obtained from satellite ocean color based models (SatPPMs) and those generated from biogeochemical ocean general circulation models (BOGCMs) represent a key resource for biogeochemical and ecological studies at global as well as regional scales. Calibration and validation of these PP models are not straightforward, however, and comparative studies show large differences between model estimates. The goal of this paper is to compare PP estimates obtained from 30 different models (21 SatPPMs and 9 BOGCMs) to a tropical Pacific PP database consisting of ~1000 14C measurements spanning more than a decade (1983- 1996). Primary findings include: skill varied significantly between models, but performance was not a function of model complexity or type (i.e. SatPPM vs. BOGCM); nearly all models underestimated the observed variance of PP, specifically yielding too few low PP (〈 0.2 gC m-2d-2) values; more than half of the total root-mean-squared model-data differences associated with the satellite-based PP models might be accounted for by uncertainties in the input variables and/or the PP data; and the tropical Pacific database captures a broad scale shift from low biomass-normalized productivity in the 1980s to higher biomass-normalized productivity in the 1990s, which was not successfully captured by any of the models. This latter result suggests that interdecadal and global changes will be a significant challenge for both SatPPMs and BOGCMs. Finally, average root-mean-squared differences between in situ PP data on the equator at 140°W and PP estimates from the satellite-based productivity models were 58% lower than analogous values computed in a previous PP model comparison six years ago. The success of these types of comparison exercises is illustrated by the continual modification and improvement of the participating models and the resulting increase in model skill.
    Description: This research was supported by a grant from the National Aeronautics and Space Agency Ocean Biology and Biogeochemistry program (NNG06GA03G), as well as by numerous other grants to the various participating investigators
    Keywords: Primary production ; Modeling ; Remote sensing ; Satellite ocean color ; Statistical analysis ; Tropical Pacific Ocean (15°N to 15°S and 125°E to 95°W)
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 18
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 24 (2010): GB3020, doi:10.1029/2009GB003655.
    Description: The performance of 36 models (22 ocean color models and 14 biogeochemical ocean circulation models (BOGCMs)) that estimate depth-integrated marine net primary productivity (NPP) was assessed by comparing their output to in situ 14C data at the Bermuda Atlantic Time series Study (BATS) and the Hawaii Ocean Time series (HOT) over nearly two decades. Specifically, skill was assessed based on the models' ability to estimate the observed mean, variability, and trends of NPP. At both sites, more than 90% of the models underestimated mean NPP, with the average bias of the BOGCMs being nearly twice that of the ocean color models. However, the difference in overall skill between the best BOGCM and the best ocean color model at each site was not significant. Between 1989 and 2007, in situ NPP at BATS and HOT increased by an average of nearly 2% per year and was positively correlated to the North Pacific Gyre Oscillation index. The majority of ocean color models produced in situ NPP trends that were closer to the observed trends when chlorophyll-a was derived from high-performance liquid chromatography (HPLC), rather than fluorometric or SeaWiFS data. However, this was a function of time such that average trend magnitude was more accurately estimated over longer time periods. Among BOGCMs, only two individual models successfully produced an increasing NPP trend (one model at each site). We caution against the use of models to assess multiannual changes in NPP over short time periods. Ocean color model estimates of NPP trends could improve if more high quality HPLC chlorophyll-a time series were available.
    Description: This research was supported by a grant from the National Aeronautics and Space Agency Ocean Biology and Biogeochemistry program (NNG06GA03G).
    Keywords: Marine primary productivity models ; BATS HOT trends ; Multidecadal climate forcing
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/plain
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  • 19
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): C08001, doi:10.1029/2006JC003852.
    Description: Application of biogeochemical models to the study of marine ecosystems is pervasive, yet objective quantification of these models' performance is rare. Here, 12 lower trophic level models of varying complexity are objectively assessed in two distinct regions (equatorial Pacific and Arabian Sea). Each model was run within an identical one-dimensional physical framework. A consistent variational adjoint implementation assimilating chlorophyll-a, nitrate, export, and primary productivity was applied and the same metrics were used to assess model skill. Experiments were performed in which data were assimilated from each site individually and from both sites simultaneously. A cross-validation experiment was also conducted whereby data were assimilated from one site and the resulting optimal parameters were used to generate a simulation for the second site. When a single pelagic regime is considered, the simplest models fit the data as well as those with multiple phytoplankton functional groups. However, those with multiple phytoplankton functional groups produced lower misfits when the models are required to simulate both regimes using identical parameter values. The cross-validation experiments revealed that as long as only a few key biogeochemical parameters were optimized, the models with greater phytoplankton complexity were generally more portable. Furthermore, models with multiple zooplankton compartments did not necessarily outperform models with single zooplankton compartments, even when zooplankton biomass data are assimilated. Finally, even when different models produced similar least squares model-data misfits, they often did so via very different element flow pathways, highlighting the need for more comprehensive data sets that uniquely constrain these pathways.
    Description: This research was supported by the U.S. National Science Foundation through the JGOFS Synthesis and Modeling Project (OCE-0097285) and the National Aeronautics and Space Agency (NAG5-11259 and NNG05GO04G), as well as numerous other grants to the various investigators who participated.
    Keywords: Ecosystem model comparison ; Biogeochemical data assimilation ; Phytoplankton functional groups
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/plain
    Format: image/tiff
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  • 20
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Recently I proposed a quantitative theory which predicts the partition of resources between vegetative growth and seed production in highly rhizomatous clonal plants (Armstrong 1982, 1983). My basic premise was that this partition should be controlled by basic geometric properties of clonal growth. My conclusions were that the ratio of resources expended on seeds and rhizomes should be relatively constant in time and space, and that the value of this ratio should be predictable from a knowledge of the allometric relationships among certain morphological characters. In the present paper I first refine this theory to yield explicit ramet-level predictions directly applicable to clonal species with densely-packed canopies. These predictions are then tested using observations on goldenrods (Solidago altissima) and mayapples (Podophyllum peltatum). In the Solidago studies, the ratio of infructescence weight to total rhizome weight was found to be asymptotically constant for the larger ramets in a clone, confirming an important prediction of the theory. A second prediction of the theory, that the ratio of infructescence weight to total rhizome weight should be constant across clones, was not confirmed using the goldenrod data. This observation may simply be due to measurement biases. An alternative hypothesis is that the prediction of this theory constitute an r-limit strategy, and so are applicable only in the limit of density independent growth. Data from Sohn and Policansky (1977) on mayapples support this latter interpretation.
    Type of Medium: Electronic Resource
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