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Textures and Rare Earth Elements Composition of Banded Iron Formations (BIF) at Njweng Prospect, Mbalam Iron Ore District, Southern Cameroon

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International Journal of Geosciences 2013年第1期4卷 146-165页

作者： Dieudonne Charles Isidore Ilouga Cheo Emmanuel Suh ghogomu richard tanwi Department of Earth Sciences Faculty of Science University of Yaoundé I Yaoundé Cameroon Economic Geology Unit Department of Geology and Environmental Science University of Buea Buea Cameroon

The REE signature of banded iron formations (BIF) and martite-goethite mineralization of the Njweng ridge (South Cameroon) are used here to decipher the nature of the ocean during the period of BIF precipitation. The textures of typical BIF categories are also presented as the only sedimentary feature. Two types of BIF facies are present at Njweng: the oxide and silicate facies. These facies show two stages of phase transformations. The first is the transformation of the original magnetite mineral into martite by oxidation resulting in trellis texture;the second is a simultaneous transformation by hydration into goethite and dehydration into martite. The samples typically show LREE depleted patterns relative to HREE, a characteristic similar to that of modern seawater. Also the strong positive Eu anomalies from the samples indicate the involvement of hydrothermal plumes of volcanic origin such as at mid ocean ridges (MOR). Yttrium (Y) has a strong positive anomaly pointing to the transportation of REEs as aqueous complexes within these ancient seas. The BIF samples have no positive Ce anomalies, suggesting that the oceans at that time were more reducing with no Ce fractionation than in present day oceans. The martite-goethite mineralization rather shows a positive Ce anomaly that derived from the enrichment in REE during the weathering of REE-bearing minerals. These results are integrated into existing literature on REE in BIFs worldwide and provide new insights into these heretofore unstudied BIFs of the northern edge of the Congo Craton.

关键词： REE BIF Martite Magnetite Alteration Njweng Cameroon

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Na-Metasomatism and Uranium Mineralization during a Two-Stage Albitization at Kitongo, Northern Cameroon: Structural and Geochemical Evidence

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International Journal of Geosciences 2012年第1期3卷 258-279页

作者： Arnaud Patrice Kouske Cheo Emmanuel Suh richard tanwi ghogomu Vincent Ngako Laboratory of Applied Geology-Metallogeny Department of Earth Sciences University of Yaoundé 1 Yaoundé Cameroon

Mapping and documentation of lithological varieties and their corresponding geochemistry at the Kitongo uranium mineralization were concerned. The Kitongo U occurrence is hosted by granitic rocks that include interleaved sequences of metasedimentary and metavolcanic rocks of the collectively termed Poli Group. U-mineralization and Na-metasomatism are related and structurally controlled. The most promising uraniferous bodies are intimately related to intersections between the ductile ENE-trending faults and the brittle conjugate R' faults postdating the shearing event. The con- centration of uranium at fault intersections rather than along individual faults suggests that these zones that are dilatational in nature were also highly permeable and therefore the hydrothermal fluids ponded there could readily precipitate U therein. A two-stage albitization has altered the foliated granitic host rock and the second albitization that has over-printed the first one is more effective at fault intersections. Whole rock geochemistry was performed by using ICP-MS and ICP-AES respectively for major oxides, trace and REE. The U-bearing rock suite exhibits restricted range in SiO2 concentration (62.89% - 70.91%) and Al2O3 (13.16% - 18.59%) and it is poor in MgO (0.02% - 1.03%), CaO (0.24% - 1.88%) and K2O (0.08% - 5.32%). The mineralized rocks are however comparatively richer in Na2O (4.33% - 10.92%) compared to their barren counterparts. The host granite and associated granodioritic rocks in the area are weakly metaluminous, peralkaline, and are calc-alkaline. They are moderately to strongly fractionated and have tholeiitic and shoshonitic affinities with moderate to high HFSE (high field strength elements) and LILE (large ion lithophile elements) enrichment. The Rb/Sr, Rb/Ba and Sr/Ba ratios are 0.31, 0.14 and 1.48, respectively. U content in the mineralized granite is up to 651 ppm while the non-mineralized rock has only 2.4 ppm U. The REE patterns of the granite show LREE enric

关键词： Uranium Kitongo Granite Albitization Strike Slip Fault Cameroon

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一个改进的地球圈层差异旋转模型

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高校地质学报 2000年第4期6卷 561-565页

作者：王心源孙岩张喜慧 richard ghogomu tanwi 杨照柱中国科学院遥感信息科学开放实验室北京100101 南京大学地球科学系内生金属矿床成矿机制研究国家重点实验室江苏南京210093 Center for Earthquake Researchand Information University of Memphis Dept.of Earth Sciences University of Yaounde

地球自转速度在长期的减慢 ,而内核自转又较其外部的地球部分转动快 ,这是由日、月对地球的潮汐摩擦引起的同一动力学背景下导致的相关现象。通过能量守衡的定量分析 ,得出地球潮汐耗散能的 11%即可导致内核自转较其外部的地球部分自转... 详细信息

地球自转速度在长期的减慢 ,而内核自转又较其外部的地球部分转动快 ,这是由日、月对地球的潮汐摩擦引起的同一动力学背景下导致的相关现象。通过能量守衡的定量分析 ,得出地球潮汐耗散能的 11%即可导致内核自转较其外部的地球部分自转快的结论。通过推理比较和定量分析 ,提出了岩石圈层、主地幔圈层与内核三个圈层的差异旋转模型 :岩石圈自转速度 <主地慢自转速度 <内核自转速度。它可能是导致大陆向西飘移—板块构造及地磁产生的重要机制之一。

关键词：潮汐能大陆向西飘移板块构造地球PREM模型

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Effect of Different Rates and Mixtures of Solid Household Waste and Faecal Sludge-Based Composts on Soil Fertility and Productivity of Sunflower (Helianthus annuus L.) in Dschang, West Cameroon

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Open Journal of Soil Science 2024年第7期14卷 448-470页

作者： Romary Ngnipa Tchinda Rodrigue Emmanuel Kenne Primus Azinwi Tamfuh Jovanie Gladys Kenfack Doris Temgoua Zombou Désiré Évariste Moundjeu Tsafack richard tanwi ghogomu Emile Temgoua Dieudonné Bitom Oyono Department of Environmental Sciences of the Higher Institute of Agriculture Wood Water and the Environment of the University of Bertoua Blabo Cameroon Department of Soil Science Soil Analysis and Environmental Chemistry Research Unit Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Mining and Mineral Engineering National Higher Polytechnic Institute University of Bamenda Bambili Cameroon Department of Animal Biology Faculty of Sciences University of Dschang Dschang Cameroon Department of Earth Sciences University of Yaounde 1 Yaounde Cameroon

The unbalanced and inadequate use of fertilizers is one of the causes of soil degradation. Combined with the ever-increasing population, it is necessary to find sustainable agricultural production alternatives. The present work aims to determine the effect of different rates and mixtutes of organic amendments on soil fertility and the performance of Sunflower (Helianthus annuus L.). In the field, treatments consisted of solid household waste and faecal sludge in the ratios of 3/5 (V1), and a mixture of faecal sludge and household waste in the ratio of 3/5 with 900 worms (V2). At the end of the composting process, V1, V2 composts and the poultry manure (PM) were applied at rates of 4, 5 and 6 t∙ha−1 in a randomized complete block design with three replications. Soil samples were collected before and after the experiment and analyzed. The main results revealed that at the end of the composting process, there was a progressive improvement in the physico-chemical properties of V1 and V2 composts. In particular, the C/N ratio, phosphorus (P) and total nitrogen (TN) initially at 16.49 ± 0.42 (V1, V2), 21.06 ± 0.07 mg∙kg−1 (V1, V2), 0.76% ± 0.08% (V1, V2) respectively, increased after 60 days to 12.40 ± 0.41 (V1), 9.74 ± 0.28 (V2) for C/N, 21.94 ± 0.63 mg∙kg−1 (V1) and 22.04 ± 0.04 mg∙kg−1 (V2) for P, 0.96% ± 0.0% (V1) and 1.22 ± 0.04 (V2) for TN. The application of 6 t∙ha−1of PM had the greatest influence on the diameter and weight of the flower heads (27.16 ± 4.01 t∙ha−1 and 230.83 ± 2.64 t∙ha−1), while 4 t∙ha−1 of V2 gave the tallest sunflower plants (110.07 ± 73.28 cm) as well as the diameter at the crown (19.30 ± 9.07 cm). However, CEC was most influenced by 4 t∙ha−1 of V1, while 4 t∙ha−1 of PM had the greatest effect on organic carbon and phosphorus. However, 5 t∙ha−1 of PM showed the highest sunflower production and yield (1.67 ± 0.21 t∙ha−1). The combination with 900 earthworms is recommended for composting and 5 t∙ha−1 of PM is recommended to obtain a better sunfl

关键词： Sunflower Faecal Sludge Household Waste Compost Soil Fertility

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