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Qinghui Zhang - One of the best experts on this subject based on the ideXlab platform.

  • pollen vegetation land use relationships in southeastern china complexity and applicability for Paleoenvironmental Reconstruction
    Ecological Indicators, 2020
    Co-Authors: Ke Zhang, Xiangdong Yang, Lingyang Kong, Qinghui Zhang
    Abstract:

    Abstract Fossil pollen, as a key indicator of vegetation landscapes, can provide abundant information of long-term land use dynamics. However, pollen-vegetation relationships are complex, and the relevant studies are rare in the large sedimentary basins associated with strong human disturbances. This study aims to investigate the pollen-vegetation/land use relationships at a large regional scale, and to supplement reference for more accurate Paleoenvironmental Reconstruction in the future. A total of 124 modern pollen samples were collected from 66 lakes in the Yangtze-Huaihe River Basin (YHRB), southeastern China. We conducted a contrastive analysis of both pollen and land use data in different spatial extents and categories. Our results reveal that the pollen assemblages of the YHRB are dominated by both arboreal and herbaceous taxa, such as Pinus, Quercus, Pterocarya, Juglans, Poaceae, Artemisia, Cruciferae, Chenopodiaceae, Compositae, and Humulus. The spatial differences of pollen assemblages in the YHRB are obvious, resulted from the confounded effects of natural environment and human disturbance. Hydrologic process plays a key role in pollen dispersal and deposition in the YHRB. Waterborne pollen is an important component of the lacustrine pollen assemblages, and fern spores and total pollen concentration can be used to indicate the degree of hydrologic process. The main source of lacustrine pollen here generally derives from sub-basins, and the source area is about 80 km. Anthropogenic impact is another significant factor determining the pollen-vegetation relationships in the YHRB. Cereal and anthropochore pollen as well as pollen diversity indexes are ideal indicators of agricultural activities. We suggest that the 4 types of estimated pollen/land-use ratios in this study, covering forest, farmland, rural land, and wetland could be used as a reference for reconstructing past land cover. Our study also demonstrates the existing problems and the potential improvements for the further studies on pollen-based Paleoenvironmental Reconstruction.

  • Pollen-vegetation/land use relationships in southeastern China: Complexity and applicability for Paleoenvironmental Reconstruction
    Ecological Indicators, 2020
    Co-Authors: Ke Zhang, Xiangdong Yang, Lingyang Kong, Qinghui Zhang
    Abstract:

    Abstract Fossil pollen, as a key indicator of vegetation landscapes, can provide abundant information of long-term land use dynamics. However, pollen-vegetation relationships are complex, and the relevant studies are rare in the large sedimentary basins associated with strong human disturbances. This study aims to investigate the pollen-vegetation/land use relationships at a large regional scale, and to supplement reference for more accurate Paleoenvironmental Reconstruction in the future. A total of 124 modern pollen samples were collected from 66 lakes in the Yangtze-Huaihe River Basin (YHRB), southeastern China. We conducted a contrastive analysis of both pollen and land use data in different spatial extents and categories. Our results reveal that the pollen assemblages of the YHRB are dominated by both arboreal and herbaceous taxa, such as Pinus, Quercus, Pterocarya, Juglans, Poaceae, Artemisia, Cruciferae, Chenopodiaceae, Compositae, and Humulus. The spatial differences of pollen assemblages in the YHRB are obvious, resulted from the confounded effects of natural environment and human disturbance. Hydrologic process plays a key role in pollen dispersal and deposition in the YHRB. Waterborne pollen is an important component of the lacustrine pollen assemblages, and fern spores and total pollen concentration can be used to indicate the degree of hydrologic process. The main source of lacustrine pollen here generally derives from sub-basins, and the source area is about 80 km. Anthropogenic impact is another significant factor determining the pollen-vegetation relationships in the YHRB. Cereal and anthropochore pollen as well as pollen diversity indexes are ideal indicators of agricultural activities. We suggest that the 4 types of estimated pollen/land-use ratios in this study, covering forest, farmland, rural land, and wetland could be used as a reference for reconstructing past land cover. Our study also demonstrates the existing problems and the potential improvements for the further studies on pollen-based Paleoenvironmental Reconstruction.

Nor Syazwani Zainal Abidin - One of the best experts on this subject based on the ideXlab platform.

  • Paleoenvironmental Reconstruction and hydrocarbon potentials of upper cretaceous sediments in the anambra basin southeastern nigeria
    International Journal of Coal Geology, 2018
    Co-Authors: Olajide Femi Adebayo, Adebanji Kayode Adegoke, Khairul Azlan Mustapha, Mutiu Adesina Adeleye, Amos Okechukwu Agbaji, Nor Syazwani Zainal Abidin
    Abstract:

    Abstract Palynological, organic petrographic, and organic geochemical analyses of the Campanian-Maastrichtian sediments in Akukwa-2 well were carried out to infer their paleoenvironments, origin of the organic matter, and hydrocarbon generation potentials. The TOC values of the analysed sediments range from 0.27–3.02 wt%, while the S2 pyrolysis yield range from 0.55 to 3.35 mg HC/g rock. This indicates that the Nkporo and Mamu sediments possess fair source generative potential. The samples contain Type III-II and Type III kerogen as shown by the present-day HI values between 58 and 292 mg HC/g TOC and pyrolysis-GC data. The organic matter within the sediments is also likely to generate mainly gas. This is in agreement with the petrographic observations, which revealed that the analysed shale samples contain abundant vitrinite macerals, apart from bituminite, alginite, cutinite, and resinite. Also, the sediments are immature to early mature in terms of hydrocarbon generation as indicated by vitrinite reflectance, biomarker maturity, and pyrolysis Tmax data. Biomarker distribution ratios, palynomorphs assemblage, and organic petrographic observations further point out that the organic materials within the sediments were of mixed aquatic and terrigenous origin and were deposited under suboxic paleodepositional conditions. Based on sedimentological, palynological, and biomarker characteristics, the environment of deposition of the analysed sediments was inferred to be a relatively quiet, shallow marine with fluvial incursion, most especially at the upper part of the intervals studied and consequently, it is a delta associated depositional environment with a fluviatile influence. The sediments are therefore suggested to be deposited in a paleogeographic setting close to vegetation source.

Luiz Carlos Ruiz Pessenda - One of the best experts on this subject based on the ideXlab platform.

  • Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region, Santa Catarina state) based on multi-proxy analysis
    Journal of Quaternary Science, 2011
    Co-Authors: Paula Garcia Carvalho Do Amaral, Paulo César Fonseca Giannini, Florence Sylvestre, Luiz Carlos Ruiz Pessenda
    Abstract:

    This paper provides a Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (d 13 C, d 15 N and C/N), microfossil (pollen and diatom) and grain-size analysis from three shallow cores (� 2.5 m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid-Holocene than today, with a gradual and continuous lagoon-sea disconnection until the present. We add to the debate regarding relative sea-level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi-proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright # 2011 John Wiley & Sons, Ltd.

Luiz Carlos Ruiz Pessenda - One of the best experts on this subject based on the ideXlab platform.

  • Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region, Santa Catarina state) based on multi-proxy analysis
    Journal of Quaternary Science, 2012
    Co-Authors: Paula Garcia Amaral, Florence Sylvestre, Paulo Cesar Fonseca Giannini, Luiz Carlos Ruiz Pessenda
    Abstract:

    This paper provides a Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (delta C-13, delta N-15 and C/N), microfossil (pollen and diatom) and grain-size analysis from three shallow cores (similar to 2.5m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid-Holocene than today, with a gradual and continuous lagoon-sea disconnection until the present. We add to the debate regarding relative sea-level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi-proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright (c) 2011 John Wiley & Sons, Ltd.

Florence Sylvestre - One of the best experts on this subject based on the ideXlab platform.

  • Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region, Santa Catarina state) based on multi-proxy analysis
    Journal of Quaternary Science, 2012
    Co-Authors: Paula Garcia Amaral, Florence Sylvestre, Paulo Cesar Fonseca Giannini, Luiz Carlos Ruiz Pessenda
    Abstract:

    This paper provides a Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (delta C-13, delta N-15 and C/N), microfossil (pollen and diatom) and grain-size analysis from three shallow cores (similar to 2.5m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid-Holocene than today, with a gradual and continuous lagoon-sea disconnection until the present. We add to the debate regarding relative sea-level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi-proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright (c) 2011 John Wiley & Sons, Ltd.

  • Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in southern Brazil (Jaguaruna region, Santa Catarina state) based on multi-proxy analysis
    Journal of Quaternary Science, 2011
    Co-Authors: Paula Garcia Carvalho Do Amaral, Paulo César Fonseca Giannini, Florence Sylvestre, Luiz Carlos Ruiz Pessenda
    Abstract:

    This paper provides a Paleoenvironmental Reconstruction of a Late Quaternary lagoon system in the Jaguaruna region of Santa Catarina state, southern Brazil. Integrated results of bulk sedimentary organic matter characterization (d 13 C, d 15 N and C/N), microfossil (pollen and diatom) and grain-size analysis from three shallow cores (� 2.5 m depth) allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca. 5500 cal a BP. The lagoonal system in this area was more extensive during the mid-Holocene than today, with a gradual and continuous lagoon-sea disconnection until the present. We add to the debate regarding relative sea-level (RSL) variations for the Brazilian coast during the Holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems. The multi-proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes, which are not necessarily linked to RSL fluctuations and/or to climatic variations. Copyright # 2011 John Wiley & Sons, Ltd.