PAN-AFRICAN CENTRAL AFRICAN FOLD BELT, WITH EMPHASIS ON BEDROCKS AND HEAVY MINERAL ANALYSIS OF RIVER ALLUVIUM IN THE NORTHERN CAMEROON
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摘要: 简要叙述冈瓦纳超大陆聚合过程和中非造山带泛非期地质构造过程，剖析了西冈瓦纳喀麦隆北部和乍得西南地区岩石构造单元及其形成的构造背景并对喀麦隆北部河流冲积物进行了重矿物分析。分析结果表明重矿物可能来自近源基岩，为西喀麦隆地体（Western Cameroon Domain）内的雷博巴（Rey Bouba）绿岩带和马约科比（Mayo Kebbi）弧岩浆岩带；重矿物中的自然金可能主要来自雷博巴绿岩带。分析结果为该地区砂金矿开采提供了一定的指示。Abstract: The assembly of Gondwanaland and Pan-African orogeny were briefly presented. Then, the lithological units and their tectonic settings in the northern Cameroon and southwestern Chad were dissected based on previous research. On this basis, heavy mineral analysis was carried out for river alluvium collected from northern Cameroon. The analysis results (species and contents of heavy mineral) were consistent with the basement rocks of the Mayo Kebbi magmatic arc belt and the Rey Bouba greenstone belt from Western Cameroon Domain (WCD). Gold in the alluvium may come from Rey Bouba greenstone belt, and the analysis results may give a prospect for alluvial gold exploit in northern Cameroon.
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图 3 巴西与非洲中西部构造单元对比及西冈瓦纳~500 Ma复原图[14]
AF—阿德马瓦断裂（Admawa Fault）；AYD—阿德马瓦-雅得地体（Admawa-Yade Domain）；SF—萨纳加断裂（Sanaga Fault）；TBF—乔利雷-班约断裂（Tchollire-Banyo Fault）；WCD—西喀麦隆地体（West Cameroon Domain）；YD—雅温得地体（Yaounde Domain）；Y—雅温得
Figure 3. Reconstruction of west Gondwana at about 500 Ma showing inferred geological provinces and potential correlations from Brazil to west-central Africa
图 4 中非造山带主要岩石构造单元和地体划分[16]
AF—阿德马瓦断裂；SF—萨纳加断裂；TBF—乔利雷-班约断裂
Figure 4. Main lithotectonic units and domains of the Central African Fold Belt
图 5 喀麦隆北部及乍得西南地区地质简图[20]
1—泛非期之后盖层；2—泛非造山晚期-后造山花岗质侵入体（＜600 Ma）；3—同构造花岗岩；4—马约科比（Mayo Kebbi）TTG岩基（665~640 Ma）；5—西喀麦隆地体内中-高级片麻岩；6—马约科比（Mayo Kebbi）中—基性杂岩（737~723 Ma）；7—新元古代低-中级变质火山-沉积序列（绿岩带）；8—古元古代-新元古代阿德马瓦-雅得地体；9—逆冲断裂；10—走滑断裂；11—国境线；TBF—乔利雷-班约断裂（Tchollire-Banyo Fault）
Figure 5. Geological sketch map of the northern Cameroon and southwestern Chad
图 6 喀麦隆北部—乍得南西地区SRTM-DEM图及主要水系分布特征（图幅范围与图 5一致）
Figure 6. SRTM-DEM and main water distribution of the northern Cameroon and southwestern Chad
图 7 横跨WCD和AYD喀麦隆北部地区河流冲积物采样位置（水系数据参考Google Earth）
Figure 7. Sample locations for river alluvium across the WCD and the AYD in northern Cameroon
图 8 河流冲积物重矿物分析结果
Figure 8. Heavy mineral analysis results for river alluvium in the northern Cameroon
表 1 喀麦隆北部河流冲积物样品采样位置、重量及金含量
Table 1. Sampling locations, weights and gold contents for river alluvium in the northern Cameroon
样品号 采样纬度 采样经度 河流冲积物总重/g 重矿物总重/g 自然金总量/粒 自然金含量/(粒·kg-1) VA-A009 8°53′22.92″ 14°30′19.44″ 916 6.50 1 1.09 VA-A017 8°51′40.54″ 14°29′23.28″ 5662 49.19 2 0.35 VA-A028 8°51′54.32″ 14°30′33.84″ 3232 26.96 1 0.31 VA-A031 8°53′34.37″ 14°30′22.32″ 14466 127.31 47 3.25 VA-A032 8°53′28.36″ 14°30′37.44″ 11923 107.98 32 2.68 VA-A035 8°46′42.89″ 14°31′43.68″ 15894 61.87 56 3.52 VA-A036 8°46′13.15″ 14°32′05.64″ 7199 49.37 50 6.95 VA-A037 8°45′57.20″ 14°32′11.76″ 5212 28.78 209 40.10 VA-A071 8°47′27.24″ 14°34′03.36″ 1829 13.56 49 26.79 VA-A075 8°46′37.42″ 14°33′51.84″ 1660 12.54 2 1.20 
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