Journal of Tropical Oceanography >
The primary sedimentary characteristics of Warm Pool in Beibu Gulf and its environmental indication*
Received date: 2017-03-01
Request revised date: 2017-09-05
Online published: 2018-02-02
Supported by
China Geological Survey Program (1212010914027)
Copyright
The development and change of a warm pool have close relationships with sedimentary environment. For the lack of integrated modern sedimentary environmental studies on the Warm Pool of Beibu Gulf, the samples of bottom sediments from the study area within the main part of the Warm Pool were collected and laboratory analysis and identification in granularity, geochemical elements and micropaleontology was carried out. The study and comparison using the above data showed that the provenance came from surrounding up continent crust. Median grain size ranged 1.07Φ~6.88Φ; SiO2 dominated in macro-geochemical elements with maximum 66.61% and followed by Al2O3; micro-geochemical elements and REEs ranged 9.05~297.00μg•g-1, 0.34~69.43μg•g-1, respectively, and an averaged chemical index of alteration (CIA) 47.33 and (La/Yb)N 7.46~10.07 and paleo-biodiversity index of foraminifera and diatom 0~2.52 meaning relatively significant spatial variation under gulf scale. There was primary difference between western and eastern parts of the study area: the former with highest concentration of large part of geo-chemical elements, fine grain, significant fractural in REEs, high CIA and relatively rich provenance and the latter being almost opposite with low elements, low CIA, and so on but with high CaO, MnO and Sr revealing limited provenance supply and probably authigenic carbonate sedimentation. Warm-water foraminifera and subtropical-tropical diatom species took advantage in the study area and ratios between the abundance of species also indicated warm and high saline seawater characteristics especially in the eastern part of the study area. This Warm Pool is either a dependent or an open system, and has a positive effect on maintaining the biological activity, biodiversity and sedimentary environment, especially carbonate sedimentation.
Key words: Beibu Gulf; warm pool; sedimentary environment; carbonate sedimentation
HUANG Xiangqing , CUI Zhen’ang , LIANG Kai , GAN Huayang , XIA Zhen , HUO Zhenhai . The primary sedimentary characteristics of Warm Pool in Beibu Gulf and its environmental indication*[J]. Journal of Tropical Oceanography, 2018 , 37(1) : 72 -89 . DOI: 10.11978/2017023
Fig. 1 Bottom sediment sampling stations in and nearby the study area of the Warm Pool of Beibu Gulf图1 北部湾暖池研究区取样站位分布 |
Fig. 2 Pie charts of averaged pollen (%)in bottom sediments of different parts of Beibu Gulf. (a) northern part of Beibu Gulf; (b) central part of Beibu Gulf; (c) southern part of Beibu Gulf图2 北部湾表层沉积物孢粉属种平均含量(单位: %)分区分布 |
Tab. 1 Granularity statistics in bottom sediments of the study area and sub-division of Beibu Gulf表1 研究区沉积物粒度及分区统计 |
各组分百分率 | 参数 | |||||||
---|---|---|---|---|---|---|---|---|
砾石 | 砂 | 粉砂 | 黏土 | 平均粒径/Φ | 分选/Φ | 偏态 | 峰态 | |
范围 | 5.3~14.6 | 3.5~85.4 | 0~71.5 | 0~31.2 | 1.1~6.9 | 1.5~3.0 | -0.4~0.3 | 0.8~1.4 |
平均值 | 10.4 | 34.5 | 46.0 | 17.8 | 5.1 | 2.2 | 0.0 | 1.0 |
变异系数 | 0.45 | 0.80 | 0.48 | 0.51 | 0.38 | 0.23 | 4.90 | 0.18 |
北部 | 11.2 | 38.8 | 43.9 | 15.1 | 4.9 | 2.1 | 0.1 | 1.3 |
中部 | 0.0 | 40.9 | 41.1 | 18.0 | 5.3 | 2.2 | 0.4 | 0.9 |
研究区东部 | 6.7 | 48.7 | 33.9 | 10.7 | 3.9 | 2.1 | -0.1 | 1.1 |
研究区西部 | 0.0 | 26.0 | 51.0 | 23.0 | 6.0 | 2.4 | 0.0 | 0.9 |
Fig. 3 Distributions of granularity parameters in bottom sediments of the study area. (a) mean grain size; (b) sorting; (c) skewness; (d) kurtosis图3 研究区表层沉积物粒度参数平面分布 |
Tab. 2 Concentration statistics of macro-geochemical elements in bottom sediments of the study area and sub-division of Beibu Gulf表2 研究区表层沉积物常量元素质量分数范围及平均值分区统计 |
质量分数/% | SiO2 | Al2O3 | Fe2O3 | CaO | MgO | K2O | Na2O | MnO | P2O5 | TiO2 |
---|---|---|---|---|---|---|---|---|---|---|
范围 | 58.52~66.61 | 3.44~13.31 | 1.76~4.96 | 4.15~16.55 | 1.09~2.26 | 1.84~2.71 | 0.66~2.01 | 0.053~0.227 | 0.070~0.102 | 0.17~0.61 |
平均值 | 61.65 | 10.16 | 3.93 | 7.52 | 1.77 | 2.27 | 1.49 | 0.091 | 0.091 | 0.49 |
变异系数 | 0.04 | 0.35 | 0.30 | 0.56 | 0.23 | 0.15 | 0.32 | 0.66 | 0.15 | 0.28 |
北部 | 66.64 | 10.67 | 4.72 | 3.06 | 1.94 | 1.87 | 1.67 | 0.065 | 0.081 | 0.49 |
中部 | 66.51 | 10.54 | 5.07 | 3.35 | 1.84 | 2.26 | 1.60 | 0.064 | 0.083 | 0.50 |
研究区东部 | 61.29 | 7.97 | 3.15 | 10.23 | 1.50 | 2.17 | 1.20 | 0.122 | 0.078 | 0.41 |
研究区西部 | 62.18 | 11.79 | 4.49 | 5.31 | 1.98 | 2.37 | 1.65 | 0.069 | 0.093 | 0.55 |
Tab. 3 Concentration statistics of micro-geochemical elements in bottom sediments of the study area and sub-division of Beibu Gulf表3 研究区表层沉积物微量元素质量分数范围及平均值分区统计 |
质量分数/(μg•g-1) | Co | Cu | Ni | Pb | Cr | Sr | Zn | Zr | Sc | V | Ga | Ba |
---|---|---|---|---|---|---|---|---|---|---|---|---|
范围 | 3.48~ 12.25 | 3.75~ 14.70 | 6.04~ 32.10 | 20.0~ 30.3 | 17.1~ 75.10 | 190~ 530 | 20.71~ 78.70 | 15.52~ 74.15 | 2.83~ 12.20 | 18.51~ 77.74 | 2.71~ 17.75 | 152~ 325 |
平均值 | 9.66 | 10.83 | 22.94 | 23.65 | 55.08 | 297 | 59.97 | 57.92 | 9.05 | 59.13 | 13.15 | 273 |
变异系数 | 0.32 | 0.38 | 0.40 | 0.14 | 0.39 | 0.42 | 0.35 | 0.33 | 0.38 | 0.34 | 0.41 | 0.19 |
北部 | 11.03 | 15.96 | 32.16 | 25.54 | 66.14 | 139 | 66.56 | 62.63 | 10.3 | 63.68 | 15.28 | 210 |
中部 | 11.83 | 15.29 | 29.57 | 24.87 | 68.57 | 139 | 67.33 | 59.83 | 10.31 | 64.30 | 15.6 | 261 |
研究区东部 | 7.49 | 8.01 | 16.38 | 22.73 | 40.93 | 390 | 46.33 | 45.87 | 7.00 | 45.53 | 9.80 | 233 |
研究区西部 | 11.45 | 12.99 | 27.97 | 25.18 | 65.57 | 221 | 70.53 | 63.15 | 10.61 | 69.57 | 15.82 | 306 |
Tab. 4 Concentration statistics of rare earth elements (REEs) in bottom sediments of the study area and sub-division of Beibu Gulf表4 研究区表层沉积物稀土元素质量分数范围及平均值分区统计 |
质量分数 /(μg•g-1) | La | Ce | Pr | Nd | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
范围 | 16.84 ~42.71 | 32.86 ~85.01 | 3.89 ~9.60 | 14.14 ~34.07 | 2.67 ~6.31 | 0.66 ~1.21 | 2.51 ~5.89 | 0.41 ~0.86 | 2.65 ~4.99 | 0.52 ~0.95 | 1.41 ~2.73 | 0.22 ~0.43 | 1.34 ~2.72 | 0.19 ~0.42 |
平均值 | 34.63 | 69.43 | 7.82 | 27.74 | 5.14 | 1.02 | 4.66 | 0.71 | 4.11 | 0.78 | 2.26 | 0.34 | 2.21 | 0.34 |
变异系数 | 0.24 | 0.24 | 0.24 | 0.23 | 0.23 | 0.20 | 0.24 | 0.22 | 0.20 | 0.20 | 0.21 | 0.22 | 0.21 | 0.22 |
北部 | 35.53 | 70.58 | 7.72 | 28.47 | 5.21 | 0.93 | 4.60 | 0.73 | 4.25 | 0.78 | 2.31 | 0.34 | 2.27 | 0.35 |
中部 | 37.2 | 72.30 | 8.20 | 30.2 | 5.49 | 1.01 | 4.81 | 0.74 | 4.22 | 0.77 | 2.23 | 0.33 | 2.27 | 0.36 |
研究区东部 | 29.49 | 58.95 | 6.69 | 23.78 | 4.40 | 0.88 | 4.00 | 0.62 | 3.63 | 0.68 | 1.97 | 0.30 | 1.95 | 0.31 |
研究区西部 | 37.62 | 75.88 | 8.56 | 30.11 | 5.61 | 1.10 | 5.04 | 0.77 | 4.40 | 0.85 | 2.41 | 0.36 | 2.37 | 0.37 |
Tab. 5 Ratio statistics of geochemical elements in bottom sediments of the study area and sub-division of Beibu Gulf表5 研究区表层沉积物地球化学元素质量分数比值的平均值分区统计 |
质量分数/(μg•g-1) | CIA | CaO/MgO | CaO/P2O5 | Sr/Ba | δEu | δCe | (La/Yb)N | (Gd/Yb)N | (La/Sm)N |
---|---|---|---|---|---|---|---|---|---|
范围 | 15.28~60.35 | 2.08~15.23 | 43.71~247.01 | 0.64~3.49 | 0.64~0.84 | 0.82~0.86 | 7.46~10.07 | 1.15~1.37 | 3.94~4.47 |
平均值 | 47.33 | 5.05 | 93.30 | 1.26 | 0.70 | 0.85 | 9.23 | 1.28 | 4.20 |
变异系数 | 0.33 | 0.89 | 0.75 | 0.78 | 0.10 | 0.02 | 0.09 | 0.06 | 0.04 |
北部 | 61.13 | 1.74 | 40.74 | 0.78 | 0.61 | 0.85 | 9.33 | 1.25 | 4.26 |
中部 | 57.22 | 1.96 | 47.60 | 0.56 | 0.63 | 0.84 | 9.96 | 1.32 | 4.23 |
研究区东部 | 37.06 | 8.11 | 143.20 | 1.98 | 0.73 | 0.83 | 8.75 | 1.22 | 4.16 |
研究区西部 | 55.61 | 2.78 | 57.75 | 0.72 | 0.68 | 0.86 | 9.47 | 1.30 | 4.20 |
Fig. 4 Distributions of macro-geochemical elements’ concentration in bottom sediments of the study area图4 研究区表层沉积物常量元素质量分数平面分布 |
Fig. 5 Distributions of main micro-geochemical elements and REEs in bottom sediments of the study area. (a) ∑1 (sum of micro-geochemical elements); (b) ∑2 (sum of micro-geochemical elements except Sr); (c) Sr; (d) ∑LREE (sum of light rare earth elements); (e) ∑MREE (sum of middle rare earth elements); (f) ∑HREE (sum of heavy rare earth elements)图5 研究区表层沉积物主要微量元素和稀土元素质量分数的平面分布 |
Fig. 6 Distributions of ratios between geochemical elements in bottom sediments of the study area图6 研究区表层沉积物地球化学元素比值分布 |
Fig. 7 Distribution patterns of standardized REEs (a, b) and macro-, micro-geochemical elements’ concentrations (c, d) in bottom sediments of the study area. (a) chondrite; (b) up continent crust; (c) macro-geochemical elements; (d) micro-geochemical elements图7 研究区站位表层沉积物稀土元素标准化分布模式(a, b)、常量元素(c)和微量元素(d)分布模式 |
Tab. 6 Dominant species of foraminifera and diatom in bottom sediments of the study area表6 研究区表层沉积物底栖类微体古生物优势种组合 |
类型 | 站位 | 优 势 种 | 含量/% | 均方差/% |
---|---|---|---|---|
有孔虫 | S19 | B. nodosaris - T. foliace - H. praecineta - P. schroeteriana | 56.86 | 0.01 |
S20 | S. orbis - Q. seminula - T. conica - P. schroeteriana | 73.58 | 0.10 | |
S22 | T. foliace - H. praecineta - P. schroeteriana - E. advenum | 64.40 | 0.07 | |
S23 | H. mantaensis - T. foliace - Q. seminula - Florilus decorus | 61.03 | 0.06 | |
S24 | T. conica - Q. seminula - B. nodosaris - P. schroeteriana - S. orbis - T. foliace | 60.48 | 0.01 | |
S26 | P. schroeteriana - H. praecineta - Q. seminula - H. mantaensis - T. foliace | 56.91 | 0.01 | |
S27 | P. schroeteriana - P. lateralis - H. praecineta - T. foliace - H. mantaensis | 52.88 | 0.03 | |
S28 | Hanzawaia concentrina - A. madagascariensis - P. schroeteriana - H. mantaensis - Q. seminula | 50.10 | 0.01 | |
硅藻 | S19 | Actinocyclus ehrenbergi - C. striata - S. fluminensis | 33.90 | 0.003 |
S20 | C. striata - M. sulcata | 53.62 | 0.002 | |
S22 | C. striata | 52.63 | 0.003 | |
S23 | C. striata - S. fluminensis - N. fasciculata | 54.29 | 0.06 | |
S24 | S. fluminensis - N. fasciculate - C. lorenziana | 42.00 | 0.03 | |
S28 | C. lorenziana - C. striata | 34.62 | 0.08 |
Tab. 7 Environmental indicators by foraminifera and diatom in bottom sediments of the study area and sub-division of Beibu Gulf表7 研究区表层沉积物微体古生物质量分数比值范围及平均值分区统计 |
质量分数 | 有孔虫 | 硅藻 | ||||
---|---|---|---|---|---|---|
浮游种/底栖种 | 温跃层种/混合层种 | 冷水种/暖水种 | 热性种/广温种 | 咸水种/半咸水种 | 浮游种/底栖种 | |
比值范围 | 0~0.91 | 0~0.36 | 0~0.37 | 0~0.49 | 0~2.20 | 0~0.33 |
北部 | 0.00 | — | — | 0.12 | 0.10 | — |
中部 | 0.02 | — | 0.13 | 0.11 | 0.12 | — |
研究区东部 | 0.02 | — | 0.11 | 0.24 | 1.00 | 0.05 |
研究区西部 | 0.44 | 0.14 | 0.17 | 0.17 | 0.25 | 0.14 |
注: 在北部湾北部和中部由于水动力作用较强, 沉积物硅藻等化石难以完整保存, 未能全面反映出数据, 故以“—”表示无数据 |
Tab. 8 Biodiversity index of foraminifera and diatom in bottom sediments of the study area and sub-division of Beibu Gulf表8 研究区表层沉积物微体古生物多样性指数H'范围及平均值分区统计 |
H' | 有孔虫 | 硅藻 | 有孔虫和硅藻 | ||||
---|---|---|---|---|---|---|---|
浮游 | 底栖 | 浮游 | 底栖 | 总浮游 | 总底栖 | ∑H' | |
范围 | 0~0.90 | 1.06~2.52 | 0~0.69 | 1.07~2.33 | 0~0.90 | 2.12~4.59 | 2.13~5.47 |
北部 | — | 1.58 | 0.00 | 1.33 | 0.00 | 2.91 | 2.91 |
中部 | 0.00 | 2.07 | — | 1.52 | 0.00 | 3.59 | 3.59 |
研究区东部 | 0.00 | 2.10 | 0.21 | 1.92 | 0.21 | 4.02 | 4.23 |
研究区西部 | 0.27 | 2.21 | 0.46 | 1.66 | 0.73 | 3.87 | 4.60 |
注: 在北部湾北部和中部由于水动力作用较强, 沉积物硅藻等化石难以完整保存, 未能全面反映出数据, 故以“—”表示无数据。 |
Fig.8 Distribution of standardized concentration of CaO, MnO, Sr and calcareous detritus in bottom sediments of research area图8 研究区表层沉积物CaO、MnO、Sr和钙质生物碎屑的相对含量分布 |
The authors have declared that no competing interests exist.
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