Marine-like potash evaporite formation on a continental playa: case study from Chott el Djerid, southern Tunisia   总被引：3，自引：0，他引：3  

Robert G. Bryant  Bruce W. Sellwood  Andrew C. Millington  Nick A. Drake 《Sedimentary Geology》1994,90(3-4):269-291

An exceptional flood in January 1990 led to the formation of a large ephemeral lake on the Chott el Djerid, a salt playa in southern Tunisia. Repeated observations made during 1990 show that the ephemeral lake underwent four evolutionary stages: (1) initial flooding, (2) evaporative concentration of lake waters, (3) the movement of concentrated brine pools over the playa surface as a result of wind action, and (4) total desiccation of the lake by September 1990. During all four stages the brine chemistry of the lake was monitored. Water inflow into the Chott el Djerid basin was found to have a consistent Ca-SO₄-Cl-rich and HCO₃-CO₃-poor chemistry, reflecting the recycling of homogeneous assemblages of Cretaceous, Mio—Pliocene and Quaternary evaporites within the catchment. As the ephemeral lake shrank, these waters produced an Na-Mg-K-Cl-SO₄ brine which was similar to modern sea water. Mineral saturation data show that, during the desiccation of the lake, saturation with respect to both gypsum and halite was achieved and that the most concentrated brines were ultimately saturated with respect to potash phases. After the desiccation of the lake the main mineral phases found on the Chott included gypsum and halite. In addition, ephemeral deposits of carnallite (observed as carnallitite,3KMgCl_3·6H₂0 + NaCl) were found. This assemblage is that which would be expected to form if the waters had undergone salt norm evaporation at 1 bar pressure at 25°C (SNORM) in the evaporation model proposed by Jones and Bodine (1987). The nature of both the brine chemistry and evaporite mineralogy provides a new and rare example of marine-like potash-bearing evaporites being formed in a contemporary continental playa.  相似文献   

A pleistocene origin for shore platforms along the Northern Illawarra Coast,New South Wales     

B.P. Brooke  R.W. Young  E.A. Bryant  C.V. Murray‐Wallace  D.M. Price 《The Australian geographer》1994,25(2):178-185

This paper examines the composition, structure and age of clastic deposits situated behind shore platforms at Austinmer and Coledale on the northern Illawarra coast, New South Wales. Our results support earlier chronological evidence of a Pleistocene history for shore platforms along the Illawarra coast. The size and fabric of sediments within these deposits indicate rapid, high‐energy deposition of bedrock eroded from platforms adjacent to the deposits. The elevations of the deposits above the modern shoreline suggest higher sea levels or higher wave energy gradients than presently occurs across these platforms. Dating of sediments within these deposits using ¹⁴C, AAR and TL techniques indicates Late Pleistocene and Late Holocene erosion of the shore platforms. Platform development was initiated before the Last Interglacial as correlative sediments lie atop relict platform surfaces landward of the modern platforms.  相似文献   

Urban irrigation in the modeling of a semi-arid urban environment: Ballona Creek watershed,Los Angeles,California     

Bryant Reyes  Terri S. Hogue  Reed M. Maxwell 《水文科学杂志》2020,65(8):1344-1357

ABSTRACT

Ballona Creek watershed in Los Angeles, California provides a unique combination of heterogeneous urban land cover, a semi-arid environment, and a large outdoor water-use flux that presents a challenge for physically-based models. We ran simulations using the Noah Land Surface Model and Parflow-Community Land Model and compared to observations of evapotranspiration (ET), runoff, and land surface temperature (LST) for the entire 11-year study period. Both models were systematically adjusted to test the impact of land cover and urban irrigation on simulation results. Monthly total runoff and ET results are greatly improved when compared to an in-situ stream gauge and meteorological tower data: from 0.64 to 0.81 for the Nash–Sutcliffe efficiency (NSE) for runoff and from a negative NSE to 0.82 for ET. The inclusion of urban irrigation in semi-arid urban environments is found to be vital, but not sufficient, for the accurate simulation of variables in the studied models.  相似文献   

A statistical analysis of tree-ring dating in conjunction with snow avalanches: Comparison of on-path versus off-path responses     

Carl L. Bryant  David R. Butler  John D. Vitek 《Environmental Geology》1989,14(1):53-59

Tree-rings were collected from snow-avalanche paths in Colorado, and from positions away from avalanche paths. The rings were examined for morphological responses to avalanche-induced trauma. Use of the Chi-square statistic revealed a significant difference in the number of morphological responses from on-path versus off-path positions. A high number of on-path trees were definitely damaged by avalanche impact in 1973; a lower number of trees from off-path positions illustrated morphologic ring-responses from random, nonavalanche, events in the same year.  相似文献   

Intertidal fauna of the industrialized Forth estuary     

D. McLusky  D. Bryant  M. Elliott  M. Teare  G. Moffat 《Marine pollution bulletin》1976,7(3):48-52

The estuarine Firth of Forth on the East Coast of Scotland receives a considerable volume of industrial and domestic effluent. This report summarizes the present status of intertidal invertebrates and their bird predators.  相似文献   

Predicted seabird distributions in the North Sea: the consequences of being hungry     

Ollason  J. G.; Bryant  A. D.; Davis  P. M.; Scott  B. E.; Tasker  M. L. 《ICES Journal of Marine Science》1997,54(4):507-517

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Seasonal variation in the consumption of food by fish in the North Sea and implications for food web dynamics   总被引：7，自引：3，他引：7  

Greenstreet  Simon P. R.; Bryant  Andrew D.; Broekhuizen  Niall; Hall  Stephen J.; Heath  Mike R. 《ICES Journal of Marine Science》1997,54(2):243-266

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Albany K-Feldspar: A New Pb Isotope Reference Material     

Janne Liebmann  Bryant Ware  Michael I.H. Hartnady  Christopher L. Kirkland  Nicholas E. Timms  Noreen J. Evans 《Geostandards and Geoanalytical Research》2023,47(3):637-655

Lead isotopes are a powerful and versatile tool to elucidate fundamental geological problems related to the formation and evolution of continental crust. K-feldspar is a popular target for Pb isotope measurement as it is prevalent in many rock types and tends to capture the initial Pb isotope composition of its parental magma. We present data for a new Pb isotope reference material: Albany K-feldspar; as well as updated data for Shap K-feldspar. Results of Pb double-spike TIMS for Albany K-feldspar are ²⁰⁶Pb/²⁰⁴Pb = 16.7872 ± 0.0062, ²⁰⁷Pb/²⁰⁴Pb = 15.5640 ± 0.0056, and ²⁰⁸Pb/²⁰⁴Pb = 36.6600 ± 0.0168 (2s). TIMS measurement results for Shap K-feldspar indicate two isotopically distinct Pb populations. LA-MC-ICP-MS, with a spatial resolution as high as 15 μm, indicates a homogeneous Pb isotopic composition in Albany K-feldspar. In accord with previous studies, our results show that scatter in the measured Pb isotope ratios, related to the low natural isotopic abundance of ²⁰⁴Pb, along with the effect of isobaric ²⁰⁴Hg-²⁰⁴Pb interference, increases at lower count rates. However, the mean Pb isotope ratios measured via LA-MC-ICP-MS using a range of spot sizes are in excellent agreement with TIMS results thus highlighting the feasibility of Pb isotope determination via LA-MC-ICP-MS to access geological information preserved in small crystals, including mineral inclusions.  相似文献   

The real-time needs of emergency managers for tropical cyclone storm tide forecasting: results of a participatory stakeholder engagement process   总被引：1，自引：0，他引：1  

Joanna Burston  Daniel Ware  Rodger Tomlinson 《Natural Hazards》2015,78(3):1653-1668

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Assessment of future climate change impact on rainfed wheat yield in the semi-arid Eastern High Plain of Algeria using a crop model     

Kourat  Tassadit  Smadhi  Dalila  Mouhouche  Brahim  Gourari  Nerdjes  Mostofa Amin  M. G.  Bryant  Christopher Robin 《Natural Hazards》2021,107(3):2175-2203

Natural Hazards - Maintaining sustainability in rainfed wheat production under changing climate is a grave concern for food security in Algeria. This study aims to assess the impact of future...  相似文献