诸广南长江铀矿田油洞断裂性质及其找矿意义研究
|
摘要
油洞断裂是长江铀矿田NW向主断裂之一,研究和勘查程度相对较低。通过对该断裂的构造变形特征、演化特征以及含矿特征的详细评价和研究工作,认为:油洞断裂是一条多期活动的构造带,在110～70 Ma之间发生了右行韧性剪切作用,断裂内花岗岩和辉绿岩均发生糜棱岩化,韧性变形自NW向SE逐渐增强,韧性变形的温度为280～350℃,形成差压力为62.6～118.1 MPa,平均值为81.4 MPa,水或流体对岩石的弱化和蚀变作用可能促进了岩石韧性变形的发生。韧性剪切作用破坏岩石的结构完整性而形成构造薄弱面,从而使其张裂、破碎,成为含铀热液迁移的通道和铀矿赋存的空间,形成较大规模的工业矿体;同时,韧性剪切带空间上产状稳定,向深部延深较大,对于深部找矿具有重大意义。长江矿田油洞断裂南东段韧性剪切作用最强的地段是进一步深部找矿的重要方向。
The Changjiang uranium orefield is one of the most important uranium resource bases in south Zhuguang area. At present, the exploration mainly focuses on NNW trending tensional structural belt. The NW trending Youdong fault is one of the main faults in this area, which is relatively low in research and exploration level. In this paper, detailed structural deformation characteristics, evolution characteristics and ore bearing characteristics of this fault are evaluated and studied. The results show that Youdong fault is a relatively shallow directed dextral ductile shear zone, which occurred between 110～70 Ma, after the mafic vein invasion and before uranium mineralization. The temperature rises to 250 ～350 ℃ and the pressure to62.6～118.1 Mpa, averaging 81.4 Mpa. The dultide transformation may be related to the weakening effect of water or fluid on rocks. After the ductile shear action, uranium-bearing siliceous filling mineralization occurred, and then processes of directed dextral brittle shearing and repeated extrusion and nappe occurred.Because ductile shear action can enhance the permeability of the rock, which make the transformed rock easier to form the migration channel for uranium ore-bearing fluid and the store space of uranium ore, thus forming a relatively large scale industrial ore body. Meanwhile, the ductile shear zone is stable in occurrence and lohgen and wider in extention, therefore, the ductile shear zone is a great significance for deep ore prospecting. This paper points out that the area with the strongest ductile shear action in the southern and eastern section of Youdong fault in Changjiang orefield is an important direction for further prospecting.
The Changjiang uranium orefield is one of the most important uranium resource bases in south Zhuguang area. At present, the exploration mainly focuses on NNW trending tensional structural belt. The NW trending Youdong fault is one of the main faults in this area, which is relatively low in research and exploration level. In this paper, detailed structural deformation characteristics, evolution characteristics and ore bearing characteristics of this fault are evaluated and studied. The results show that Youdong fault is a relatively shallow directed dextral ductile shear zone, which occurred between 110～70 Ma, after the mafic vein invasion and before uranium mineralization. The temperature rises to 250 ～350 ℃ and the pressure to62.6～118.1 Mpa, averaging 81.4 Mpa. The dultide transformation may be related to the weakening effect of water or fluid on rocks. After the ductile shear action, uranium-bearing siliceous filling mineralization occurred, and then processes of directed dextral brittle shearing and repeated extrusion and nappe occurred.Because ductile shear action can enhance the permeability of the rock, which make the transformed rock easier to form the migration channel for uranium ore-bearing fluid and the store space of uranium ore, thus forming a relatively large scale industrial ore body. Meanwhile, the ductile shear zone is stable in occurrence and lohgen and wider in extention, therefore, the ductile shear zone is a great significance for deep ore prospecting. This paper points out that the area with the strongest ductile shear action in the southern and eastern section of Youdong fault in Changjiang orefield is an important direction for further prospecting.
引文
[1]范洪海,何德宝,徐浩,等.全国花岗岩型铀矿资源潜力评价[J].铀矿地质, 2012, 28(6):335-341.
[2]黄国龙,吴烈勤,邓平,等.粤北花岗岩型铀矿找矿潜力及找矿方向[J].铀矿地质, 2006, 22(5):267-275.
[3]姚振凯.我国铀矿床的大地构造类型及其主要特征[J].大地构造与成矿学, 1983, 7(2):25-33.
[4]黄国龙,曹豪杰,凌洪飞,等.粤北油洞岩体SHRIMP锆石U-Pb年龄、地球化学特征及其成因研究[J].地质学报, 2012, 86(4):577-586.
[5]黄国龙,刘鑫扬,孙立强,等.粤北长江岩体的锆石U-Pb定年、地球化学特征及其成因研究[J].地质学报,2014,88(5):836-849.
[6]周航兵,潘家永,钟福军,等.粤北长江铀矿田细粒黑云母花岗岩的成因及其与铀成矿关系[J].矿物岩石,2018,38(1):10-19.
[7]曹豪杰,黄国龙,许丽丽,等.诸广花岗岩体南部油洞断裂带辉绿岩脉的Ar-Ar年龄及其地球化学特征[J].地质学报,2013,87(7):957-966.
[8]郭春影,徐浩,白芸,等.粤北长江铀矿田构造控矿规律初探[J].矿物学报,2013,33(S2):207-208.
[9]黄国龙,尹征平,凌洪飞,等.粤北地区302矿床沥青铀矿的形成时代、地球化学特征及其成因研究[J].矿床地质,2010,29(2):352-360.
[10]李出安,邹和平.广东南雄断裂带Ar-Ar年龄及其地质意义[J].中山大学学报(自然科学版),2011,50(1):129-132.
[11]余心起,吴淦国,舒良树,等.白垩纪时期赣杭构造带的伸展作用[J].地学前缘,2006,13(3):31-43.
[12]White S H,Burrows S E,Carreras J,et al.On mylonites in ductile shear zones[J].Journal of Structural Geology,1980,2(1-2):175-187.
[13]Tullis J,Yund R A.Dynamic recrystallization of feldspar:A mechanism for ductile shear zone formation[J].Geology,1985,13(4):238-241.
[14]Willingshofer E,Sokoutis D,Burg J P.Lithospheric-scale analogue modelling of collision zones with a pre-existing weak zone[J].Geological Society London Special Publications,2005,243(1):277-294.
[15]Platt J P.Secondary cleavages in ductile shear zones[J].Journal of Structural Geology,1984,6(4):439-442.
[16]Babaie H A,Tour T E L.Semibrittle and cataclastic deformation of hornblende-quartz rocks in a ductile shear zone[J].Tectonophysics,1994,229(1-2):19-30.
[17]Twiss R J.Theory and applicability of a recrystallized grain size paleopiezometer[J].Pure&Applied Geophysics,1977,115(1-2):227-244.
[18]金淑燕,孙天泽,徐实昆.辉绿岩脆-塑性变形转化的高温高压实验研究[J].地球科学,2000,25(6):565-572.
[19]侯泉林,李继亮,孙枢,等.浅层次微型韧性剪切带的发现及其形成机理讨论[J].科学通报,1995,40(7):636-638.
[20]琚宜文,王桂梁,姜波.浅层次脆性变形域中煤层韧性剪切带微观分析[J].中国科学:地球科学,2003,33(7):626-635.
[21]刘俊来,Weber.浅成断层带的低温脆-韧性破裂共生机制[J].科学通报,1999,44(8):864-869.
[22]陈柏林.浅变质细碎屑岩中韧性剪切变形构造岩特征及其类型划分[J].岩石矿物学杂志,1998,17(1):30-34.
[23]刘俊来.上部地壳岩石流动与显微构造演化-天然与实验岩石变形证据[J].地学前缘,2004,11(4):503-509.
[24]马立杰,刘俊来,崔迎春.浅部地壳岩石变形过程中地质流体的化学效应-水解弱化及其微观机制[J].地学前缘,2001,8(4):244-244.
[25]Hier-Majumder S,Kohlstedt D L.Role of dynamic grain boundary wetting in fluid circulation beneath volcanic arcs[J].Geophysical Research Letters,2006,33(8):153-172.
[26]Ghosh S K,Sengupta S.Progressive development of structures in a ductile shear zone[J].Journal of Structural Geology,1987,9(3):277-287.
[27]Bussolotto M,Benedicto A,Moen-Maurel L,et al.Fault deformation mechanisms and fault rocks in micritic limestones:Examples from Corinth rift normal faults[J].Journal of Structural Geology,2015,77:191-212.
[28]王勇生,朱光,刘国生.糜棱岩化过程中绿泥石多型与结晶度的演变---以郯庐断裂带南段为例[J].矿物学报,2004,24(3):271-277.
[29]冯建忠,邵世才,汪东波,等.陕西八卦庙金矿脆-韧性剪切带控矿特征及成矿构造动力学机制[J].中国地质,2002,29(1):58-66.
[30]邱添,朱永峰.新疆萨尔托海石英菱镁岩中发育的韧性剪切带及其对金矿的控制[J].岩石学报,2012,28(7):2250-2256.
[31]杨兴科,姬金生.东天山大型韧性剪切带基本特征与金矿预测[J].大地构造与成矿学,1998,(3):209-218.
[2]黄国龙,吴烈勤,邓平,等.粤北花岗岩型铀矿找矿潜力及找矿方向[J].铀矿地质, 2006, 22(5):267-275.
[3]姚振凯.我国铀矿床的大地构造类型及其主要特征[J].大地构造与成矿学, 1983, 7(2):25-33.
[4]黄国龙,曹豪杰,凌洪飞,等.粤北油洞岩体SHRIMP锆石U-Pb年龄、地球化学特征及其成因研究[J].地质学报, 2012, 86(4):577-586.
[5]黄国龙,刘鑫扬,孙立强,等.粤北长江岩体的锆石U-Pb定年、地球化学特征及其成因研究[J].地质学报,2014,88(5):836-849.
[6]周航兵,潘家永,钟福军,等.粤北长江铀矿田细粒黑云母花岗岩的成因及其与铀成矿关系[J].矿物岩石,2018,38(1):10-19.
[7]曹豪杰,黄国龙,许丽丽,等.诸广花岗岩体南部油洞断裂带辉绿岩脉的Ar-Ar年龄及其地球化学特征[J].地质学报,2013,87(7):957-966.
[8]郭春影,徐浩,白芸,等.粤北长江铀矿田构造控矿规律初探[J].矿物学报,2013,33(S2):207-208.
[9]黄国龙,尹征平,凌洪飞,等.粤北地区302矿床沥青铀矿的形成时代、地球化学特征及其成因研究[J].矿床地质,2010,29(2):352-360.
[10]李出安,邹和平.广东南雄断裂带Ar-Ar年龄及其地质意义[J].中山大学学报(自然科学版),2011,50(1):129-132.
[11]余心起,吴淦国,舒良树,等.白垩纪时期赣杭构造带的伸展作用[J].地学前缘,2006,13(3):31-43.
[12]White S H,Burrows S E,Carreras J,et al.On mylonites in ductile shear zones[J].Journal of Structural Geology,1980,2(1-2):175-187.
[13]Tullis J,Yund R A.Dynamic recrystallization of feldspar:A mechanism for ductile shear zone formation[J].Geology,1985,13(4):238-241.
[14]Willingshofer E,Sokoutis D,Burg J P.Lithospheric-scale analogue modelling of collision zones with a pre-existing weak zone[J].Geological Society London Special Publications,2005,243(1):277-294.
[15]Platt J P.Secondary cleavages in ductile shear zones[J].Journal of Structural Geology,1984,6(4):439-442.
[16]Babaie H A,Tour T E L.Semibrittle and cataclastic deformation of hornblende-quartz rocks in a ductile shear zone[J].Tectonophysics,1994,229(1-2):19-30.
[17]Twiss R J.Theory and applicability of a recrystallized grain size paleopiezometer[J].Pure&Applied Geophysics,1977,115(1-2):227-244.
[18]金淑燕,孙天泽,徐实昆.辉绿岩脆-塑性变形转化的高温高压实验研究[J].地球科学,2000,25(6):565-572.
[19]侯泉林,李继亮,孙枢,等.浅层次微型韧性剪切带的发现及其形成机理讨论[J].科学通报,1995,40(7):636-638.
[20]琚宜文,王桂梁,姜波.浅层次脆性变形域中煤层韧性剪切带微观分析[J].中国科学:地球科学,2003,33(7):626-635.
[21]刘俊来,Weber.浅成断层带的低温脆-韧性破裂共生机制[J].科学通报,1999,44(8):864-869.
[22]陈柏林.浅变质细碎屑岩中韧性剪切变形构造岩特征及其类型划分[J].岩石矿物学杂志,1998,17(1):30-34.
[23]刘俊来.上部地壳岩石流动与显微构造演化-天然与实验岩石变形证据[J].地学前缘,2004,11(4):503-509.
[24]马立杰,刘俊来,崔迎春.浅部地壳岩石变形过程中地质流体的化学效应-水解弱化及其微观机制[J].地学前缘,2001,8(4):244-244.
[25]Hier-Majumder S,Kohlstedt D L.Role of dynamic grain boundary wetting in fluid circulation beneath volcanic arcs[J].Geophysical Research Letters,2006,33(8):153-172.
[26]Ghosh S K,Sengupta S.Progressive development of structures in a ductile shear zone[J].Journal of Structural Geology,1987,9(3):277-287.
[27]Bussolotto M,Benedicto A,Moen-Maurel L,et al.Fault deformation mechanisms and fault rocks in micritic limestones:Examples from Corinth rift normal faults[J].Journal of Structural Geology,2015,77:191-212.
[28]王勇生,朱光,刘国生.糜棱岩化过程中绿泥石多型与结晶度的演变---以郯庐断裂带南段为例[J].矿物学报,2004,24(3):271-277.
[29]冯建忠,邵世才,汪东波,等.陕西八卦庙金矿脆-韧性剪切带控矿特征及成矿构造动力学机制[J].中国地质,2002,29(1):58-66.
[30]邱添,朱永峰.新疆萨尔托海石英菱镁岩中发育的韧性剪切带及其对金矿的控制[J].岩石学报,2012,28(7):2250-2256.
[31]杨兴科,姬金生.东天山大型韧性剪切带基本特征与金矿预测[J].大地构造与成矿学,1998,(3):209-218.