江西省新余式铁矿中深部铁矿勘查探讨
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摘要
赣中铁矿田(新余式)铁矿位于南华造山带北缘,武功山—北武夷山隆起带西段武功隆起东南侧的神山背斜南翼。自20世纪50年代中期发现航磁异常,随即开展勘查工作,至80年代末,查明铁矿资源储量5亿多吨。但认为铁矿成因是沉积变质型,在走向上延伸大于60km,倾向延深小于1km。笔者认真总结了新余式铁矿田矿床成因特征与成矿规律及对典型矿区构造特征的研究,认为区内变质岩原岩主要形成于优地槽海底火山喷发环境,是火山沉积变质型硅铁建造的铁矿床。因此,铁矿层所在的地层是寻找该类矿床的直接找矿标志。矿层形态呈"红绸舞"式,一般具有"浅繁深简"的特征。文中重点对"红绸舞"式褶皱展开研究,认为在矿区内铁矿层次级褶皱具有规律性:平面上每100～300m出现一个"台阶"。"台阶"是由一个背形和一个向形组成,影响垂深40～300m。平面与垂向"台阶"间距规律自北向南,由浅到深,均是由小到大。这组背向形是矿区的二期构造,北西向展布,呈左行雁行排列。二期褶皱是在固流作用下形成的不同规模、形态各异、简繁更迭的各种不协调褶皱为特征。其核部铁矿层厚度较大,一般是翼部铁矿层厚度的2～12倍,一般在二期褶皱构造的轴部及转折端附近铁矿体形态复杂,更次一级小褶曲十分发育,其厚度也随之增大,倾向延伸也增大,是铁矿层赋存的有利构造部位。矿区所控制的铁矿层延深大于2.6km。在总结区域与矿区铁矿勘查经验的基础上,文中提出"就矿找矿和寻找有利构造部位相结合"的找矿模式,给赣中铁矿田新余式铁矿未来边深部(第二找矿空间)勘查工作提供借鉴。
Ganzhong iron ore field(the Xinyu type) is located in the south limb of Shenshan anticline developed in the southeast side of Wugong uplift which is situated in the west of Wugong North Wuyi mountain uplift belt of the north of South China orogenic belt.The aeromagnetic anomalies have been discovered since the mid 1950s,then the primary exploration work was carried out,and more than 500 million tons of iron ore resources have been found until the end of the 1980 s.However,the metallogenesis of the iron ore has been considered to be the sedimentary metamorphic type.The ore deposit extends more than 60 km along the strike and less than 1 km in the dip direction.The author presided over the project from the beginning to the end of the whole process,and had summarized the genetic features and metallogenic regularity of the Xinyu iron ore field,and had studied the structural characteristics in the typical mining area.It is considered that the protoliths of the metamorphic rocks are mainly formed under eugeosynclinal submarine volcanic eruption environment,which belongs to a metamorphic volcanic-sedimentary type of ore deposit of siliceous-iron formation.Therefore,the iron ore strata are the direct marker for its prospecting.The morphology of iron ore-bed shows a pattern like the traditional "red silk dance",having the features of "shallow-complex,deep-simple".The present paper is focusing at giving the details of the red silk dance type foldings.The secondary folds of the iron ore layer show a stepwise pattern;there would be regularly one step for each 100 300 meters in the plane.A step is composed of one antiform and one synform with vertical extension of 40 300 m.The horizontal and vertical distances between the steps are getting larger from north to south and from shallow to deep.The antiform and synform are second stage structures of the mining area,trending NW with sinistral en echelon arrangement.The secondary folds are of the characteristics of disharmonic foldings with different scales,shapes,and numerous changes in their fold styles formed under the effect of solid flow.The thickness of the iron ore layer in the core is 1 2 times as that in the limbs.Generally,the shape of iron orebody is getting complex in the core and in the hinge of the secondary folds where small folds of lower rank are well-developed,and the thickness and extension of the ore are also increased;thus,the core and the hinge of the secondary folds become the favorable structure sites for the iron ore mining.In the mining area,the extent of the controlled iron ore is more than 2.6 km.On the basis of summarizing the prospecting work performed both in the mining area and in the region,the author puts forward the model of prospecting as "to seek the unknown deposit from the known deposit by looking for favorite structural site".This study would provide a reference for the exploration work on the deeper zones of the Xinyu iron ore in Ganzhong iron ore field in the future.
Ganzhong iron ore field(the Xinyu type) is located in the south limb of Shenshan anticline developed in the southeast side of Wugong uplift which is situated in the west of Wugong North Wuyi mountain uplift belt of the north of South China orogenic belt.The aeromagnetic anomalies have been discovered since the mid 1950s,then the primary exploration work was carried out,and more than 500 million tons of iron ore resources have been found until the end of the 1980 s.However,the metallogenesis of the iron ore has been considered to be the sedimentary metamorphic type.The ore deposit extends more than 60 km along the strike and less than 1 km in the dip direction.The author presided over the project from the beginning to the end of the whole process,and had summarized the genetic features and metallogenic regularity of the Xinyu iron ore field,and had studied the structural characteristics in the typical mining area.It is considered that the protoliths of the metamorphic rocks are mainly formed under eugeosynclinal submarine volcanic eruption environment,which belongs to a metamorphic volcanic-sedimentary type of ore deposit of siliceous-iron formation.Therefore,the iron ore strata are the direct marker for its prospecting.The morphology of iron ore-bed shows a pattern like the traditional "red silk dance",having the features of "shallow-complex,deep-simple".The present paper is focusing at giving the details of the red silk dance type foldings.The secondary folds of the iron ore layer show a stepwise pattern;there would be regularly one step for each 100 300 meters in the plane.A step is composed of one antiform and one synform with vertical extension of 40 300 m.The horizontal and vertical distances between the steps are getting larger from north to south and from shallow to deep.The antiform and synform are second stage structures of the mining area,trending NW with sinistral en echelon arrangement.The secondary folds are of the characteristics of disharmonic foldings with different scales,shapes,and numerous changes in their fold styles formed under the effect of solid flow.The thickness of the iron ore layer in the core is 1 2 times as that in the limbs.Generally,the shape of iron orebody is getting complex in the core and in the hinge of the secondary folds where small folds of lower rank are well-developed,and the thickness and extension of the ore are also increased;thus,the core and the hinge of the secondary folds become the favorable structure sites for the iron ore mining.In the mining area,the extent of the controlled iron ore is more than 2.6 km.On the basis of summarizing the prospecting work performed both in the mining area and in the region,the author puts forward the model of prospecting as "to seek the unknown deposit from the known deposit by looking for favorite structural site".This study would provide a reference for the exploration work on the deeper zones of the Xinyu iron ore in Ganzhong iron ore field in the future.
引文
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[2]戴元裕.江西省新余太平山铁矿区叠加褶皱构造剖析[J].地质找矿论,1986,1(2):13-22.
[3]龚剑飞.新余良山铁矿矿区褶皱构造规律和生产实践初探[J].江西冶金,2008,28(1):17-20.
[4]江西省地质矿产厅.江西省岩石地层[M].武汉:中国地质大学出版社,1997.
[5]Frietsch R.On the magmatic origin of the iron ores of theKiruna type[J].Economic Geology,1978,73:478-485.
[6]许温复,王仁根.赣中新余式变质铁矿勘查过程中的小构造研究[J].江西地质科技动态,1983,58:18-29.
[7]翟裕生.关于构造流体成矿作用研究的几个问题[J].地学前缘,1996,3(4):230-234.
[8]翟裕生.地史中成矿演化的趋势和阶段[J].地学前缘,1997,4(4):197-200.
[9]曹新志,张旺生,孙华山.我国深部找矿研究进展综述[J].地质科技情报,2009,28(2):104-108.
[10]蔡国庆.冯家峪铁矿区铁矿成矿规律及找矿方向研究[J].金属矿山,2009,4:78-80.
[11]叶天竺,薛建玲.金属矿床深部找矿中的地质研究[J].中国地质,2007,34(5):885-869.
[12]常印佛,刘湘培,吴吉昌.长江中下游铜铁成矿带[M].北京:地质出版社,1991.
[13]袁见齐,朱上庆,翟裕生.矿床学[M].北京:地质出版社,1979.
[14]余志庆,汤家富,符鹤琴.“新余式”铁矿地质特征及其成因[J].矿床地质,1989,8(4):1-10.
[15]Shahab P J.The role of deep structures in the distribution ofsome major ore deposits in Iran,NE of the Zagros thrustzoned[J].Geodynamics,1999,28:237-250.