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Ning Zhong - One of the best experts on this subject based on the ideXlab platform.
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A continuous 13.3-ka record of seismogenic dust events in Lacustrine Sediments in the eastern Tibetan Plateau.
Scientific reports, 2017Co-Authors: Hanchao Jiang, Ning Zhong, Wei Shi, Siqi Zhang, Gaozhong NieAbstract:Lacustrine Sediments on the eastern Tibetan Plateau (TP) contain a wealth of information on local and regional tectonic activity. High-resolution grain-size and magnetic susceptibility measurements were conducted on the 23.4-m-thick Lixian Lacustrine sedimentary sequence spanning from 19.3 to 6.0 ka, revealing 70 prehistoric seismic events on the eastern TP. The seismic events caused intermittent increases in source materials that endowed the samples of an individual event layer with a gradual fining trend along the C = M line on a C (one percentile)-M (median diameter) plot. Grain-size distribution and end-member modeling imply that dust particles of
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a continuous 13 3 ka record of seismogenic dust events in Lacustrine Sediments in the eastern tibetan plateau
Scientific Reports, 2017Co-Authors: Hanchao Jiang, Ning Zhong, Wei Shi, Siqi Zhang, Gaozhong NieAbstract:Lacustrine Sediments on the eastern Tibetan Plateau (TP) contain a wealth of information on local and regional tectonic activity. High-resolution grain-size and magnetic susceptibility measurements were conducted on the 23.4-m-thick Lixian Lacustrine sedimentary sequence spanning from 19.3 to 6.0 ka, revealing 70 prehistoric seismic events on the eastern TP. The seismic events caused intermittent increases in source materials that endowed the samples of an individual event layer with a gradual fining trend along the C = M line on a C (one percentile)-M (median diameter) plot. Grain-size distribution and end-member modeling imply that dust particles of <20 μm in size were transported primarily by long-term suspension, while medium to coarse silt and sand were transported primarily by short-term suspension, such as aeolian transport constrained by local topography. Provenance analysis based on U-Pb zircon ages indicates that dust particles generated by earthquakes at Lixian had no effect on dust deposition at Xinmocun and Diaolin, and vice versa. These prehistoric seismic events, revealed by variations in grain size and magnetic susceptibility, thus provide invaluable information on the long-term behavior of local seismic activity.
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Geochemical evidence of windblown origin of the Late Cenozoic Lacustrine Sediments in Beijing and implications for weathering and climate change
Palaeogeography Palaeoclimatology Palaeoecology, 2016Co-Authors: Hanchao Jiang, Gaoxuan Guo, Xiangmin Cai, Jessica A. Thompson, Ning ZhongAbstract:Abstract The origin of Lacustrine Sediments in the middle latitudes of Asia remains controversial. In this study, we conducted major and trace element analyses on 86 Lacustrine samples from the X5 core in Beijing to determine their origin and provenance. The results indicate that their abundances all varied in relatively narrow ranges, similar to those of the samples in the Chinese Loess Plateau (CLP). A high correlation of major and trace element abundances exists between our Lacustrine samples and the CLP samples. UCC-normalized major and trace element abundances also have a similar pattern between the Lacustrine and the CLP samples, with the exception of a few elements with high solubility, such as Mg. In the ternary diagrams of A–CN–K, La–Th–Sc and Zr/10–Th–Sc, and the correlation maps of major/trace elements and their ratios, four groups of the X5 Lacustrine samples with different sedimentation stages (3.16–2.7 Ma, 2.7–1.8 Ma, 1.8–0.9 Ma and 0.9–0 Ma) overlap well with each other and with the CLP samples, indicating that the X5 Lacustrine samples are likely of windblown origin and possibly shared common, unchanged dust source regions with the CLP since the Late Pliocene. This interpretation is supported by the overlap of the Lacustrine samples from Beijing with the CLP samples in the correlation maps of Ms vs. sorting, Ms vs. skewness, Ms vs. kurtosis, and kurtosis vs. skewness. Analysis of the frequency and cumulative frequency curves indicates that the X5 Lacustrine Sediments were dominantly transported by the winter monsoon and the westerly circulation. Given more scattered distributions of different elemental ratios and grain size parameters of the X5 core Lacustrine Sediments compared to those of the CLP samples, local dust particles must have contributed occasionally, which deserves further investigation in the future. Several chemical ratios, such as Rb/Sr, Na 2 O/Al 2 O 3 , CaO/Al 2 O 3 , and chemical index of alteration (CIA), were calculated for the Lacustrine samples in Beijing. Comparison of these ratios' variations with those of the sea level of the South China Sea and the global benthic δ 18 O record indicates that Na 2 O/Al 2 O 3 and CIA can be regarded as sensitive indicators of chemical weathering of Lacustrine dust Sediments in the mid-latitudes of Northern Hemisphere.
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provenance and earthquake signature of the last deglacial xinmocun Lacustrine Sediments at diexi east tibet
Geomorphology, 2014Co-Authors: Hanchao Jiang, Xue Mao, Huili Yang, Ning ZhongAbstract:Abstract Well-preserved Lacustrine Sediments are found in some areas in East Tibet. This region is characterized by a windy and semi-arid climate, alpine valleys, and frequent earthquakes. Measurements of rare earth elements, observations from a scanning electron microscope and a high-resolution record of grain-size measurements allowed us to compare fine Sediments from the Xinmocun section in the Diexi Lake, with loess from the Chinese Loess Plateau and South China. Results indicate that fine grains of the Xinmocun Lacustrine Sediments were transported by wind and trapped in the lake, whereas the > 16 μm fraction was likely from local sources. The grain-size changes within the section repeatedly show abrupt coarsening and upward fining, probably due to palaeoearthquake events. Large earthquakes in the study area often caused rockfalls and landslides, exposing fine Sediments that had accumulated on mountains' slopes. The fine grains were then retransported by wind to the Diexi Lake. Optically stimulated luminescence dating of the Xinmocun section indicates continuous deposition from 18.65 to 10.63 ka. These results indicate that palaeoearthquakes in the study area had a mean recurrence interval of ~ 0.32 ka. Therefore, we propose that Lacustrine Sediments in a tectonically active region have the potential to record a continuous history of palaeoearthquakes. Palaeoearthquakes probably produced numerous rockfalls and landslides in alpine valleys and provided significant sources of regional eolian dust.
Hanchao Jiang - One of the best experts on this subject based on the ideXlab platform.
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A continuous 13.3-ka record of seismogenic dust events in Lacustrine Sediments in the eastern Tibetan Plateau.
Scientific reports, 2017Co-Authors: Hanchao Jiang, Ning Zhong, Wei Shi, Siqi Zhang, Gaozhong NieAbstract:Lacustrine Sediments on the eastern Tibetan Plateau (TP) contain a wealth of information on local and regional tectonic activity. High-resolution grain-size and magnetic susceptibility measurements were conducted on the 23.4-m-thick Lixian Lacustrine sedimentary sequence spanning from 19.3 to 6.0 ka, revealing 70 prehistoric seismic events on the eastern TP. The seismic events caused intermittent increases in source materials that endowed the samples of an individual event layer with a gradual fining trend along the C = M line on a C (one percentile)-M (median diameter) plot. Grain-size distribution and end-member modeling imply that dust particles of
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a continuous 13 3 ka record of seismogenic dust events in Lacustrine Sediments in the eastern tibetan plateau
Scientific Reports, 2017Co-Authors: Hanchao Jiang, Ning Zhong, Wei Shi, Siqi Zhang, Gaozhong NieAbstract:Lacustrine Sediments on the eastern Tibetan Plateau (TP) contain a wealth of information on local and regional tectonic activity. High-resolution grain-size and magnetic susceptibility measurements were conducted on the 23.4-m-thick Lixian Lacustrine sedimentary sequence spanning from 19.3 to 6.0 ka, revealing 70 prehistoric seismic events on the eastern TP. The seismic events caused intermittent increases in source materials that endowed the samples of an individual event layer with a gradual fining trend along the C = M line on a C (one percentile)-M (median diameter) plot. Grain-size distribution and end-member modeling imply that dust particles of <20 μm in size were transported primarily by long-term suspension, while medium to coarse silt and sand were transported primarily by short-term suspension, such as aeolian transport constrained by local topography. Provenance analysis based on U-Pb zircon ages indicates that dust particles generated by earthquakes at Lixian had no effect on dust deposition at Xinmocun and Diaolin, and vice versa. These prehistoric seismic events, revealed by variations in grain size and magnetic susceptibility, thus provide invaluable information on the long-term behavior of local seismic activity.
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Geochemical composition of the last deglacial Lacustrine Sediments in East Tibet and implications for provenance, weathering, and earthquake events
Quaternary International, 2017Co-Authors: Lianji Liang, Hanchao JiangAbstract:Abstract Identifying and understanding the respective influence of climate and tectonic processes becomes a frontier topic in tectonically active mountain ranges. In the eastern Tibetan Plateau, earthquake occurred frequently and usually led to formation of many dammed lakes. In this study, a last deglacial section of Lacustrine Sediments at Xinmocun in eastern Tibet is selected for conventional X-ray fluorescence (XRF) and Scanning XRF (SXRF) elemental analysis. The high correlation of major and trace element abundances between the Xinmocun Lacustrine samples and the loess-soil samples from the Chinese Loess Plateau (CLP) supports the previous view of the eolian origin of the Xinmocun Lacustrine Sediments. Analysis of major element abundances, ratios, and trace element ratios indicates that the dust provenance of the Xinmocun Lacustrine Sediments is different from that of the CLP, and is similar to that of the loess at Ganzi and Hongyuan nearby the study area. The significant variations of most geochemical elements and their close coupling with grain-size variations cannot be reasonably explained by the changes in transport dynamics of eolian dust, and is possibly caused by the intermittent changes in available dust provenance. Frequent earthquakes triggered abundant landslides and provided large amounts of dust for the study area. Accordingly, in the >16 μm fraction of the Xinmocun grain-size record, many element abundances and their ratios, such as SiO2/Al2O3, TiO2/Al2O3, CaO/Al2O3, Sr/Al2O3, Rb/Sr, and Na2O/Al2O3, can be regarded as sensitive indicators of earthquake events in the tectonically active regions. SXRF measurements at the U-channel surface can provide some cost-effective indicators of seismic events, such as Si/Al, Ti/Al, Ca/Al, Sr/Al, Zr/Rb, and Rb/Sr. Significant variations in most element abundances and their ratios of the Xinmocun Lacustrine Sediments correlate closely with those of its grain-size record. They all show no increasing or decreasing trends with time. These suggest that tectonic activities characterized by seismic events possibly had a major role on the landscape erosion in the eastern Tibetan Plateau, while the climatic influence seems minor.
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Geochemical evidence of windblown origin of the Late Cenozoic Lacustrine Sediments in Beijing and implications for weathering and climate change
Palaeogeography Palaeoclimatology Palaeoecology, 2016Co-Authors: Hanchao Jiang, Gaoxuan Guo, Xiangmin Cai, Jessica A. Thompson, Ning ZhongAbstract:Abstract The origin of Lacustrine Sediments in the middle latitudes of Asia remains controversial. In this study, we conducted major and trace element analyses on 86 Lacustrine samples from the X5 core in Beijing to determine their origin and provenance. The results indicate that their abundances all varied in relatively narrow ranges, similar to those of the samples in the Chinese Loess Plateau (CLP). A high correlation of major and trace element abundances exists between our Lacustrine samples and the CLP samples. UCC-normalized major and trace element abundances also have a similar pattern between the Lacustrine and the CLP samples, with the exception of a few elements with high solubility, such as Mg. In the ternary diagrams of A–CN–K, La–Th–Sc and Zr/10–Th–Sc, and the correlation maps of major/trace elements and their ratios, four groups of the X5 Lacustrine samples with different sedimentation stages (3.16–2.7 Ma, 2.7–1.8 Ma, 1.8–0.9 Ma and 0.9–0 Ma) overlap well with each other and with the CLP samples, indicating that the X5 Lacustrine samples are likely of windblown origin and possibly shared common, unchanged dust source regions with the CLP since the Late Pliocene. This interpretation is supported by the overlap of the Lacustrine samples from Beijing with the CLP samples in the correlation maps of Ms vs. sorting, Ms vs. skewness, Ms vs. kurtosis, and kurtosis vs. skewness. Analysis of the frequency and cumulative frequency curves indicates that the X5 Lacustrine Sediments were dominantly transported by the winter monsoon and the westerly circulation. Given more scattered distributions of different elemental ratios and grain size parameters of the X5 core Lacustrine Sediments compared to those of the CLP samples, local dust particles must have contributed occasionally, which deserves further investigation in the future. Several chemical ratios, such as Rb/Sr, Na 2 O/Al 2 O 3 , CaO/Al 2 O 3 , and chemical index of alteration (CIA), were calculated for the Lacustrine samples in Beijing. Comparison of these ratios' variations with those of the sea level of the South China Sea and the global benthic δ 18 O record indicates that Na 2 O/Al 2 O 3 and CIA can be regarded as sensitive indicators of chemical weathering of Lacustrine dust Sediments in the mid-latitudes of Northern Hemisphere.
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provenance and earthquake signature of the last deglacial xinmocun Lacustrine Sediments at diexi east tibet
Geomorphology, 2014Co-Authors: Hanchao Jiang, Xue Mao, Huili Yang, Ning ZhongAbstract:Abstract Well-preserved Lacustrine Sediments are found in some areas in East Tibet. This region is characterized by a windy and semi-arid climate, alpine valleys, and frequent earthquakes. Measurements of rare earth elements, observations from a scanning electron microscope and a high-resolution record of grain-size measurements allowed us to compare fine Sediments from the Xinmocun section in the Diexi Lake, with loess from the Chinese Loess Plateau and South China. Results indicate that fine grains of the Xinmocun Lacustrine Sediments were transported by wind and trapped in the lake, whereas the > 16 μm fraction was likely from local sources. The grain-size changes within the section repeatedly show abrupt coarsening and upward fining, probably due to palaeoearthquake events. Large earthquakes in the study area often caused rockfalls and landslides, exposing fine Sediments that had accumulated on mountains' slopes. The fine grains were then retransported by wind to the Diexi Lake. Optically stimulated luminescence dating of the Xinmocun section indicates continuous deposition from 18.65 to 10.63 ka. These results indicate that palaeoearthquakes in the study area had a mean recurrence interval of ~ 0.32 ka. Therefore, we propose that Lacustrine Sediments in a tectonically active region have the potential to record a continuous history of palaeoearthquakes. Palaeoearthquakes probably produced numerous rockfalls and landslides in alpine valleys and provided significant sources of regional eolian dust.
Gaozhong Nie - One of the best experts on this subject based on the ideXlab platform.
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A continuous 13.3-ka record of seismogenic dust events in Lacustrine Sediments in the eastern Tibetan Plateau.
Scientific reports, 2017Co-Authors: Hanchao Jiang, Ning Zhong, Wei Shi, Siqi Zhang, Gaozhong NieAbstract:Lacustrine Sediments on the eastern Tibetan Plateau (TP) contain a wealth of information on local and regional tectonic activity. High-resolution grain-size and magnetic susceptibility measurements were conducted on the 23.4-m-thick Lixian Lacustrine sedimentary sequence spanning from 19.3 to 6.0 ka, revealing 70 prehistoric seismic events on the eastern TP. The seismic events caused intermittent increases in source materials that endowed the samples of an individual event layer with a gradual fining trend along the C = M line on a C (one percentile)-M (median diameter) plot. Grain-size distribution and end-member modeling imply that dust particles of
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a continuous 13 3 ka record of seismogenic dust events in Lacustrine Sediments in the eastern tibetan plateau
Scientific Reports, 2017Co-Authors: Hanchao Jiang, Ning Zhong, Wei Shi, Siqi Zhang, Gaozhong NieAbstract:Lacustrine Sediments on the eastern Tibetan Plateau (TP) contain a wealth of information on local and regional tectonic activity. High-resolution grain-size and magnetic susceptibility measurements were conducted on the 23.4-m-thick Lixian Lacustrine sedimentary sequence spanning from 19.3 to 6.0 ka, revealing 70 prehistoric seismic events on the eastern TP. The seismic events caused intermittent increases in source materials that endowed the samples of an individual event layer with a gradual fining trend along the C = M line on a C (one percentile)-M (median diameter) plot. Grain-size distribution and end-member modeling imply that dust particles of <20 μm in size were transported primarily by long-term suspension, while medium to coarse silt and sand were transported primarily by short-term suspension, such as aeolian transport constrained by local topography. Provenance analysis based on U-Pb zircon ages indicates that dust particles generated by earthquakes at Lixian had no effect on dust deposition at Xinmocun and Diaolin, and vice versa. These prehistoric seismic events, revealed by variations in grain size and magnetic susceptibility, thus provide invaluable information on the long-term behavior of local seismic activity.
Zhongping Lai - One of the best experts on this subject based on the ideXlab platform.
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Luminescence chronology and radiocarbon reservoir age determination of Lacustrine Sediments from the Heihai Lake, NE Qinghai-Tibetan Plateau and its paleoclimate implications.
Journal of Earth Science, 2018Co-Authors: Zhongping Lai, Xiangjun Liu, Yixuan Wang, Qiufang Chang, Xiaoyun YangAbstract:The accurately determining the lake 14C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence (OSL) dating method is employed to date samples from highstand Lacustrine Sediments, palaeoshoreline, fluvial terrace, and the alluvial fan of the Heihai Lake catchment. Accelerator mass spectrometry (AMS) 14C dating was also used to date fossil plants from highstand Lacustrine Sediments. Based on the calculations of linear regression with OSL against radiocarbon ages for same layers of two sections, the quantitative 14C reservoir ages were estimated to lie between 3 353 and 3 464 yr during the 1.8 to 2.4 ka, which showed temporal variation. The sources of old carbon are the dissolution of carbonate bedrocks distributed along the Kunlun Mountain. The OSL ages of the different members of the hydatogen sedimentary system at Heihai Lake catchment indicate that a stronger hydrologic condition occurred from 3.0±0.2 to 1.8±0.2 ka, with a maximum lake level of 9 m higher than present. This humid stage was widely recorded in different Sediments on the QTP and Chinese Loess Plateau (CLP), indicating its broad synchronicity across the Asian Summer Monsoon region. The enhanced East Asian Summer Monsoon (EASM) and the Indian Summer Monsoon (ISM) resulted in the increase of moisture availability for the Heihai Lake area during this stage.
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Abnormal Rb/Sr ratio in Lacustrine Sediments of Qaidam Basin, NE Qinghai-Tibetan Plateau: A significant role of aeolian dust input
Quaternary International, 2018Co-Authors: Zhongping Lai, Xiangjun Liu, Qishun Fan, Haicheng WeiAbstract:Abstract The Rb/Sr ratio is an important indicator of weathering intensity in both Lacustrine and loess Sediments because of the inertness of the Rb element and the activity of the Sr element during the weathering process. Generally, the environmental interpretation of Rb/Sr ratio proxy in Lacustrine Sediments is contrary to that in the loess-paleosol sequence: it shows a negative correlation between the Rb/Sr ratio and chemical weathering intensity in Lacustrine Sediments, but shows a positive pattern in the loess-paleosol sequence. However, in this study, we investigated the Rb/Sr ratio of a Lacustrine core (ISL1A) from Qarhan Salt Lake (QSL) in eastern Qaidam Basin (QB), and found the Rb/Sr ratio indicated a positive correlation with regional precipitation. This pattern is similar to that of the loess-paleosol sequence rather than the Lacustrine Sediments. According to grain size statistics and the comparison of Rb/Sr ratio with other proxies (halite and calcite contents, grain size, and F values of grain size discriminant function), we preliminarily proposed that the abundant input of aeolian materials, transported by the strong northwest wind, cause these unexpected Rb/Sr ratio fluctuations in the ISL1A core. The comparison between background Rb and Sr elemental data of relevant regions and these of the core indicated the aeolian origin of Rb/Sr ratio in the Lacustrine Sediments, and the Rb and Sr elemental composition probably represents the geochemical characteristics of the dust source area. The Sr-Nd isotopic composition indicates that the erosive paleo-lake strata in western QB could be the origin of aeolian materials in Lacustrine Sediments in the QSL, as well as the loess deposits in Dulan County, Qinghai Lake Basin, and Xining Basin. The regional correlation between proxies of the ISL1A core and other aeolian records also supports the aeolian origin of detrital input in the core. Finally, we propose that the origin of the detrital input must be distinguished before the Rb/Sr ratio is applied as a weathering intensity proxy in Lacustrine Sediments, especially in arid basins.
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Distinguishing aeolian signature from Lacustrine Sediments of the Qaidam Basin in northeastern Qinghai-Tibetan Plateau and its palaeoclimatic implications
Aeolian Research, 2012Co-Authors: Haicheng Wei, Zhongping LaiAbstract:Abstract Qarhan playa is located in the eastern-central Qaidam Basin in the northeastern Qinghai-Tibetan Plateau. As a lake-depocenter since the Pleistocene and surrounded by Gobi and yardang fields, it might have deposited abundant aeolian materials. Distinguishing its aeolian signature from Lacustrine Sediments is important for understanding the landform processes and environmental changes, which is the focus of the current study. Based on major-elements analysis, microtextures of quartz grains, and features of grain-size frequency curves and other grain-size parameters, we demonstrate the existence of aeolian component in the Lacustrine sequences of a 102 m core (ISL1A). Grain-size distribution curve statistics on 60 samples from two extreme palaeoclimate environments (hyperarid and humid), as well as multi-proxies records comparison, indicate that the mode at about 40 μm represents the aeolian component and the 10–70 μm fraction of grain-size is a valid proxy of East Asian winter monsoon, and that the 70–650 μm fraction represents the intensity of dust storms. The erosive Lacustrine Sediments in the western Qaidam Basin and the alluvial/fluvial fans in nearby piedmont are probably important sources for these aeolian materials. The similarities of major-element data for samples from the Qaidam Basin (both Lacustrine and loess), Qinghai Lake (loess), and the Chinese Loess Plateau (loess) indicate that the Qaidam Basin is a dust source for the loess in Qinghai Lake and the Chinese Loess Plateau.
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Applicability of a quartz OSL standardised growth curve for De determination up to 400 Gy for Lacustrine Sediments from the Qaidam Basin of the Qinghai-Tibetan Plateau
Quaternary Geochronology, 2009Co-Authors: Hao Long, Zhongping Lai, Qishun Fan, Yongjuan Sun, Xiangjun LiuAbstract:Abstract The standardised growth curve (SGC) for quartz OSL has recently been developed as a practical means to reduce measurement times when determining palaeodoses using quartz of aeolian Sediments, especially loess and desert sand from the same section or the same geographical area. In the present study, we test the performance of SGCs for Lacustrine Sediments of three cores in the Qaidam Basin of the Qinghai-Tibetan Plateau (QTP) in China. A total of nine samples were collected (three samples from each of the three cores), and silt-sized (38–63 μm) quartz was extracted for the experiment. The results demonstrated that: (a) Nine samples display similar dose–response curves up to a regeneration dose of 600 Gy using single aliquot regenerative-dose (SAR) protocol, suggesting the existence of a standardised growth curve for Lacustrine Sediments in the Qaidam Basin; (b) For samples with D e s of up to ∼400 Gy, the D e s determined by the SGC are in agreement with the D e s by the SAR protocol, suggesting that the SGC approach could be used for D e determination up to a dose of ∼400 Gy for Lacustrine samples from the Qaidam Basin of the Qinghai-Tibetan Plateau in China; (c) The saturation dose for these samples is more than 600 Gy, and in the growth curve a linear growth part was observed in the high dose range of >200 Gy.
Adebanji Kayode Adegoke - One of the best experts on this subject based on the ideXlab platform.
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hydrocarbon potential of early cretaceous Lacustrine Sediments from bima formation yola sub basin northern benue trough ne nigeria insight from organic geochemistry and petrology
Journal of African Earth Sciences, 2017Co-Authors: Babangida Sarki M Yandoka, Wan Hasiah Abdullah, M B Abubakar, Adebanji Kayode Adegoke, A S Maigari, A I Haruna, Usman Y YaroAbstract:Abstract The Early Cretaceous Lacustrine Sediments from Bima Formation in the Yola Sub-basin, Northern Benue Trough, northeastern Nigeria were studied based on organic geochemistry and petrology. This is in other to provide information on hydrocarbon generation potential; organic matter type (quality), richness (quantity), origin/source inputs, redox conditions (preservation) and thermal maturation in relation to thermal effect of Tertiary volcanics. The total organic carbon (TOC) contents ranges from 0.38 to 0.86 wt % with extractable organic matter (EOM) below 1000 ppm and pyrolysis S2 yield values from 0.16 to 0.68 mg/g, suggesting poor to fair source rock richness. Based on kerogen pyrolysis and microscopy coupled with biomarker parameters, the organic matters contain Type I (Lacustrine algae), Type III (terrestrially derived land-plants) and Type IV kerogens deposited in a mixed Lacustrine-terrestrial environment under suboxic to relatively anoxic conditions. This suggest potential occurrence of Early Cretaceous Lacustrine Sediments (perhaps Lower Cretaceous petroleum system) in Yola Sub-basin of the Northern Benue Trough as present in the neighbouring basins of Chad, Niger and Sudan Republics that have both oil and gas generation potential within the same rift trend (WCARS). Vitrinite reflectance (%Ro) and Tmax values of the Lacustrine shales ranges from 1.12 to 2.32 VRo% and 448–501 °C, respectively, indicating peak-late to post-maturity stage. This is supported by the presence of dark brown palynomorphs, amorphous organic matter and phytoclasts as well as inertinite macerals. Consequently, the organic matters in the Lacustrine shales of Bima Formation in the Yola Sub-basin appeared as a source of oil (most likely even waxy) and gas prone at a relatively deeper part of the basin. However, the high thermal maturity enhanced the organic matters and most of the hydrocarbons that formed in the course of thermal maturation were likely expelled to the reservoir rock units and further cracked into secondary or major gas probably due to thermal effects of Tertiary volcanic intrusion known to be present in the basin.
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geochemical characterisation of early cretaceous Lacustrine Sediments of bima formation yola sub basin northern benue trough ne nigeria organic matter input preservation paleoenvironment and palaeoclimatic conditions
Marine and Petroleum Geology, 2015Co-Authors: Babangida Sarki M Yandoka, Wan Hasiah Abdullah, M B Abubakar, Adebanji Kayode Adegoke, Mohammed Hail HakimiAbstract:The Bima Formation is the oldest lithogenetic unit occupying the base of the Cretaceous successions in the Yola Sub-basin of the Northern Benue Trough. It is differentiated into Lower (B1), Middle (B2) and Upper (B3) Bima Members. Integrated organic and inorganic geochemical studies were applied on the Lacustrine Sediments of the Bima Formation with the aim of reconstructing the palaeodepositional environment and organic matter input in response to climate and tectonism. The analysed Sediments were deposited in a freshwater Lacustrine environment with a low-salinity stratified water column and suboxic to relatively anoxic conditions, as indicated by the bulk geochemical parameters. The biomarkers provide evidence for a contribution of aquatic algae and microorganisms, with a significant amount of terrigenous organic matter input. The preservation of the organic matter is possibly attributed to the stratified water column with low salinity and suboxic to relatively anoxic conditions. Based on the geochemistry of major and trace elements, the Sediments were deposited during semi-arid climatic conditions within passive continental margin setting. This agrees with the tectonic events in the West and Central African Rift System (WCARS) during the Early Cretaceous period.
