Practice of medium-large scale geological mapping for special issues in basic-ultrabasic intrusions:A case study of the Pobei intrusion in northeast Tarim Plate
-
摘要:
目前,1:5万地质填图规范中缺少对基性-超基性侵入岩填图方法的系统总结。以塔里木东北部坡北基性-超基性岩体为例,开展专题地质填图实践,在岩体地质、地球物理、遥感和地球化学综合调查的基础上,建立了科学问题、地质填图、矿床预测相结合的填图方法。将坡北基性-超基性岩体作为一个岩浆序列,根据岩浆性质与含矿性特征划分为2个岩浆亚序列,5个岩浆单元,分别对应不同的岩性组合。与岩浆亚序列相对应存在2类岩浆矿床,其中赋存铜镍矿化的岩相主要为橄榄岩相,含磁铁矿、钛铁矿的岩相主要与辉长岩、辉长苏长岩、辉石岩相有关。从野外踏勘、实测剖面等多个角度探讨了基性-超基性侵入岩1:5万专题地质填图的方法,为此类工作提供了有益探索。
Abstract:1:50000 geological mapping is an important foundation geological work. However, there has been little research on geological mapping method of basic-ultrabasic intrusions. With the Pobei Cu-Ni sulfide deposit as the study case, and on the basis of practice of 1:50000 geological mapping for special issues, geological survey by geological mapping, geological physics, remote sensing and geological chemistry, the authors designed a synthetical method combining scientific questions, geological mapping and prospecting. The Pobei basic-ultrabasic intrusion is a magma suite which can be divided into 2 sub-suites according to mineralization type and magma nature, the Cu-Ni sulfide mineralization is related to peridotite facies, whereas the magnetite and ilmentite mineralization occur in gabbro, gabbronorite and pyroxenite. The Pobei basic-ultrabasic intrusion can also be separated into 5 units corresponding to 5 types of lithofacies. The practices on 1:50000 geological mapping are focused on field survey, measured sections, mapping routes arrangement, magma suites and units, structure mapping method, alteration mapping method, mapping process, map layout, prospecting and some other aspects, which provide implications for the present geological mapping for basic-ultrabasic intrusions.
-
Key words:
- basic-ultrabasic rocks /
- geological mapping for special issues /
- magma suite /
- mapping units /
- deposit
-
表 1 坡北基性-超基性岩体填图单元划分及特征
Table 1. Mapping units and characteristics of Pobei basic-ultrabasic intrusion
序列 亚序列 单元 岩性 代号 野外产状及特征 特征金属矿物组合 接触关系 脉岩 辉绿岩 βμ 脉状,风化面黑色,细粒结构 斜长玢岩 χ 脉状,灰绿色带黄色调,斑状结构,斑晶为斜长石、黑云母等 闪长岩 δ 脉状,新鲜面灰白色,粗粒花岗结构,含黑云母(5%) 花岗岩 γ 脉状,新鲜面肉红色,块状构造,花岗结构。锆石U-Pb年龄为251.4±1.8Ma[7] 坡北基性-超基性岩体序列 未分 Ⅴ 辉长岩 νP5 岩枝状或透镜状,风化面青灰色,辉长结构,蚀变弱 黄铁矿、磁黄铁矿 侵入接触 第二亚序列 Ⅳ 纯橄岩 σP4 负地形,风化面呈黄绿色,弱磁性 磁铁矿 二辉橄榄岩 负地形,风化面黑色,块状构造,橄榄石可见伊丁石化,强磁性 磁铁矿、磁黄铁矿、镍黄铁矿、黄铜矿,局部见孔雀石化 侵入接触 含长二辉橄榄岩 橄榄二辉岩 负地形,透镜状,风化面灰黑色,块状构造,弱磁性 暗色橄榄辉长岩 负地形,风化面铁锈红色,条纹构造,橄榄石发育伊丁石化,强磁性。锆石U-Pb年龄为269.9±1.7Ma[6] 第一亚序列 Ⅲ 橄榄辉长岩 σνP3 正地形,风化面黑绿色,块状,抗风化,中粗粒辉长结构,含星点状硫化物 黄铁矿、磁黄铁矿、黄铜矿 Ⅱ 橄榄辉长苏长岩 σνοP2-2 地形起伏很小,风化面浅褐红色,岩石多破碎,辉长结构,含橄榄石(5%) 钛铁矿、磁铁矿(少)、黄铜矿、磁黄铁矿 辉长苏长岩 νοP2-1 大面积出露,地形起伏很小,风化面灰黑色,块状,中细粒结构,斜方辉石绢石化 Ⅰ 辉长岩 νP1 大面积出露,风化面青灰色,岩石多破碎,局部有磁铁矿体。锆石U-Pb年龄为276.1±1.9Ma[6] 磁铁矿、磁黄铁矿、黄铜矿 -
[1] 王涛, 计文化, 胡建民, 等.专题地质填图及有关问题探讨[J].地质通报, 2016, 35(5):633-641. http://dzhtb.cgs.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20160501&journal_id=gbc
[2] 高秉璋, 洪大卫, 郑基俭, 等.花岗岩类区1:5万区域地质填图方法指南[M].武汉:中国地质大学出版社, 1991.
[3] 姜常义, 程松林, 叶书锋, 等.新疆北山地区中坡山北镁铁质岩体岩石地球化学与岩石成因[J].岩石学报, 2006, 22(1):115-126. http://www.oalib.com/paper/1472075
[4] 苏本勋, 秦克章, 孙赫, 等.新疆北山地区红石山镁铁质-超镁铁质岩体的矿物学特征:对同化混染和结晶分异过程的启示[J].岩石学报, 2009, 25(4):873-887. http://www.cnki.com.cn/Article/CJFDTOTAL-XBDI2012S1029.htm
[5] 姜常义, 郭娜欣, 夏明哲, 等.塔里木板块东北部坡一镁铁质-超镁铁质层状侵入体岩石成因[J].岩石学报, 2012, 28(7):2209-2223. http://www.oalib.com/paper/1475422
[6] Xue S C, Qin K Z, Li C S, et al. Geochronological, Petrological, and Geochemical Constraints on Ni-Cu Sulfide Mineralization in the Poyi Ultramafic-Troctolitic Intrusion in the Northeast Rim of the Tarim Craton, Western China[J]. Economic Geology, 2016, 111:1465-1484. doi: 10.2113/econgeo.111.6.1465
[7] Su B X, Qin K Z, Sakyi P A, et al. Geochemistry and geochronology of acidic rocks in the Beishan region, NW China:petrogenesis and tectonic implications[J]. Journal of Asian Earth Sciences 2011, 41:31-43. doi: 10.1016/j.jseaes.2010.12.002
[8] 周维屏, 陈克强, 简人初, 等. 1:50000区调地质填图新方法[M].武汉:中国地质大学出版社, 1993.
[9] 李建星, Chen S F, 毛晓长, 等.中(西)澳地质填图对比及对中国填图的启示[J].地质通报, 2015, 34(12):2143-2149. http://dzhtb.cgs.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20151201&journal_id=gbc
[10] 郭娜欣. 塔里木板块东北部坡北岩体内镁铁质层状岩系岩石成因[D]. 长安大学硕士学位论文, 2012.
http://cdmd.cnki.com.cn/Article/CDMD-10710-1013017850.htm [11] 王子玺. 塔里木板块东北部坡北岩体中两类岩浆成矿作用[D]. 长安大学硕士学位论文, 2016.
http://cdmd.cnki.com.cn/Article/CDMD-10710-1016749444.htm [12] 李忠全, 刘顺.构造地质学(第三版)[M].北京:地质出版社, 2010:1-370.
[13] 高亚林, 乔富贵, 卢健全, 等.金川铜镍硫化物矿床中特富矿石分布特征及成因[J].地球科学与环境学报, 2014, 36(1):68-79.
[14] 潘兆橹, 赵爱醒, 潘铁虹.结晶学及矿物学(下册)(第三版)[M].北京:地质出版社, 1994:1-282.
[15] 常丽华, 陈曼云, 金巍, 等.透明矿物薄片鉴定手册[M].北京:地质出版社, 2006:1-258.
[16] Lowell J D. Lateral and vertical alteration-minieralization zoning in porphyry ore deposits[J]. Economic Geology, 1970, 65(4):373-408. doi: 10.2113/gsecongeo.65.4.373
[17] 汤中立, 白云来.华北古大陆西南缘构造格架与成矿系统[J].地学前缘, 1999, 6(2):271-283. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-DIDD199910001400.htm
[18] 王润民, 赵昌龙.新疆喀拉通克一号铜镍硫化物矿床[M].北京:地质出版社, 1991:1-298.
[19] 胡道功, Patrick J B, 吴珍汉, 等.中美合作东昆仑造山带地质填图的启示:填图理念与填图方法[J].地质通报, 2009, 28(10):1411-1418. http://dzhtb.cgs.cn/ch/reader/view_abstract.aspx?flag=1&file_no=20091007&journal_id=gbc
[20] 汤中立, 焦建刚, 闫海卿, 等.小岩体成(大)矿理论体系[J].中国工程科学, 2015, 17(2):4-18.
[21] 焦建刚, 汤中立, 闫海卿, 等.金川铜镍硫化物矿床的岩浆质量平衡与成矿过程[J].矿床地质, 2012, 31(6):1135-1148. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ201206002.htm
[22] 焦建刚, 汤中立, 钱壮志, 等.新疆东天山地区图拉尔根铜镍硫化物矿床的成因及成矿过程[J].岩石学报, 2012, 28(11):3772-3786. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB201211027.htm
[23] 焦建刚, 王勇, 钱壮志, 等.新疆喀拉通克铜镍硫化物矿床Y9岩体年代学与成岩成矿机制探讨[J].矿床地质, 2014, 33(4):675-688. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ201404001.htm
[24] Liu L, Zhou J, Jiang D, et al. Lithological discrimination of the mafic-ultramafic complex, Huitongshan, Beishan, China:Using ASTER data[J]. Journal of Earth Science, 2014, 25(3):529-536. doi: 10.1007/s12583-014-0437-3
[25] 李世金, 孙丰月, 高永旺, 等.小岩体成矿理论指导与实践——青海东昆仑夏日哈木铜镍矿找矿突破的启示及意义[J].西北地质, 2012, 45(4):187-191. http://www.cqvip.com/QK/93232X/201204/44599525.html