内蒙古核桃坝地区流纹斑岩的地球化学特征及与铀富集的关系

摘要/Abstract

摘要：

内蒙古核桃坝地区流纹斑岩体与该区铀成矿有着密切关系,为了寻求找矿突破,通过地球化学和岩浆与构造演化等方法,着重讨论流纹斑岩和构造与铀富集的关系。该流纹斑岩体位于多伦火山盆地榛子山破火山口南部,岩石富硅(w(SiO₂)= 70.15%~78.58%),富碱(w(Na₂O+K₂O)=7.49%~10.82%),属钾质(w(K₂O)=5.28%~9.30%);A/CNK的值在0.84~1.28之间,在火山岩TAS分类图解中全部样品均落入亚碱性流纹岩范围内,属于亚碱性系列流纹岩类;稀土总量高(∑REE=254.47×10^-6~499.99×10^-6),其中轻稀土元素富集,重稀土元素亏损,轻重稀土分馏程度强;亲石元素Rb、Th相对富集,特别是U含量(6.66×10^-6~966.00×10^-6)异常富集,部分数据极高,而Sr和Eu明显亏损。岩石岩浆物质来源于下地壳的部分熔融,侵位于后碰撞构造环境,属于A2型花岗岩类型。伸展构造背景下的富铀流纹斑岩侵位、后期促进铀运移富集的成矿构造及富铀热液随构造上移并进一步萃取等多种事件共同作用,最终促成了核桃坝铀矿床的形成。

关键词: 核桃坝, 流纹斑岩, 地球化学, 构造, 铀

Abstract:

Rhyolite porphyry in Hetaoba, Inner Mongolia, is closely associated with uranium mineralization of the area. In order to strengthen the theory research and seek the prospecting breakthrough, this article focuses on the relationship between uranium mineralization and rhyolite porphyry, structure by the methods of geochemistry and magma and tectonic evolution. The pluton is located in the southern of Zhenzishan caldera in Duolun volcano basin. The rock has high SiO₂ content (70.15%-78.58%), high K₂O (5.28%-9.30%) and are enriched in alkali contents (Na₂O+K₂O=7.49%-10.82%). It belongs to the alkaline rhyolite as shown in the plot of TAS. Rhyolite porphyry in Hetaoba shows high REE contents and is relatively enriched in LREE, Rb, Th, with evidently negative Eu and Sr anomalies. Especially, U element content is extremely high (6.66×10^-6-966.00×10^-6). The magma came from partial melting of the lower crust materials, and the pluton, belonging to A2 subtype granite, was likely emplaced in the extensional post-collision setting. Eventually, these factors including emplacement of rhyolite porphyry, the ore-forming structure in the late stage, the emplacement and extraction of hydrothermal with rich uranium, have led to the formation of the Hetaoba uranium deposit.

Key words: Hetaoba, rhyolite porphyry, geochemistry, structure, uranium

中图分类号:

P588

蒋孝君, 剡鹏兵, 薛伟, 邢亚杰, 刘小刚, 颜小波. 内蒙古核桃坝地区流纹斑岩的地球化学特征及与铀富集的关系[J]. 现代地质, 2017, 31(02): 225-233.

JIANG Xiaojun, YAN Pengbing, XUE Wei, XING Yajie, LIU Xiaogang, YAN Xiaobo. Geochemical Characteristics of Rhyolite Porphyry and Relationship Between the Rock and Enriched Uranium in Hetaoba, Inner Mongolia[J]. Geoscience, 2017, 31(02): 225-233.

图/表 9

参考文献 26

[1]	郑亚东, OAVIS G A, 王踪, 等. 燕山带中生代主要构造事件与板块构造背景问题[J]. 地质学报, 2000, 74(4):289-302.
[2]	邓晋福, 刘厚祥, 赵海玲, 等. 燕辽地区燕山期火成岩与造山模型[J]. 现代地质, 1996, 10(2): 137-148.
[3]	邱家骧, 廖群安. 北京地区中生代与中生代火山岩的酸度、系列、构造环境及岩浆成因[J]. 岩石矿物学杂志, 1998, 17(2): 104-117.
[4]	朱勤文, 路凤香, 谢意红, 等. 大陆边缘扩张型火山岩组合——松辽盆地周边中生代火山岩研究[J]. 岩石学报, 1997, 18(4): 91-99.
[5]	林强, 葛文春, 孙德有, 等. 中国东北地区中生代火山岩的大地构造意义[J]. 地质科学, 1998, 33(2): 129-139.
[6]	何政军, 李锦轶, 牛宝贵, 等. 燕山-阴山地区晚侏罗世强烈推覆-隆升事件及沉积响应[J]. 地质论评, 1998, 44(4): 407-418.
[7]	JAHN B M, WU F Y, CAPDEVILA R. Highly evolved juvenile graniles with tetrad REE patterns: the Woduhe and Baerzhe granites from the Great Xing’an Mountain in NE China[J]. Lithos, 2001, 59: 171-198. DOI URL
[8]	WHALEN J B, CURRIE K L, CHAPPELL B W, et al. Characterization and origin of aluminous A-type granites from the Lachlan Fold belt, southeastern Australia[J]. Journal of Petrology, 1997, 38: 371-391. DOI URL
[9]	WHALEN J B, CURRIE K L, CHAPPELL B W. A-type granites: geochemical characteristics, discrimination and petrogenesis[J]. Contribution to Mineralogy and Petrology, 1987, 95: 407-419. DOI URL
[10]	EBY G N. Chemical subdivision of the A-type granitoids: petrogenetic and tectonic implications[J]. Geology, 1992, 20: 641-644. DOI URL
[11]	XU W L, JI W Q, PEI F P, et al. Triassic volcanism in eastern Heilongjiang and Jilin provinces, NE China: Chronology, geochemistry, and tectonic implications[J]. Journal of Asian Earth Sciences, 2009, 34(3): 392-402. DOI URL
[12]	王建国, 和钟铧, 许文良. 大兴安岭南部钠闪石流纹岩的岩石成因:年代学和地球化学证据[J]. 岩石学报, 2013, 29(3): 853-863.
[13]	WILSON M. Igneous Petrogenesis[M]. London: Unwin Hyman Press, 1989:1-121.
[14]	葛文春, 林强, 孙德有, 等. 大兴安岭中生代两类流纹岩成因的地球化学研究[J]. 地球科学——中国地质大学学报, 2000, 25(2): 172-178.
[15]	张吉衡. 大兴安岭中生代火山岩年代学及地球化学研究[D]. 武汉: 中国地质大学, 2009: 1-105.
[16]	葛文春, 李献华, 林强, 等. 呼伦湖早白垩世碱性流纹岩的地球化学特征及其意义[J]. 地质科学, 2001, 36(2): 176-183.
[17]	WU F Y, JAHN B M, WILDE S A, et al. Highly fractionated I-type granites in NE China (I): geochronology and petrogenesis[J]. Lithos, 2003, 66: 241-273. DOI URL
[18]	蒋孝君, 刘正宏, 徐仲元, 等. 内蒙古镶黄旗乌兰哈达中二叠世碱长花岗岩锆石U-Pb年龄和地球化学特征[J]. 地质通报, 2013, 32(11): 1760-1768.
[19]	王荃. 内蒙古中部中朝与西伯利亚古板块间缝合线的确定[J]. 地质学报, 1986, 60(1): 33-43.
[20]	孙德有, 吴福元, 张艳斌, 等. 西拉木伦河—长春—延吉板块缝合带的最后闭合时间——来自吉林大玉山花岗岩体的证据[J]. 吉林大学学报(地球科学版), 2004, 34(2): 174-181.
[21]	孙德有. 吉中—辽北地区显生宙花岗岩的形成时代、地球化学特征与构造背景[D]. 西安: 西北大学, 2005:1-20.
[22]	徐仲元, 刘正宏, 杨振升. 内蒙古大青山地区中生代造山运动及构造演化[J]. 长春科技大学学报, 2001(4): 317-322.
[23]	LI J Y. Permian geodynamic setting of Northeast China and adjacent regions: closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate[J]. Journal of Asian Earth Sciences, 2006, 26: 207-224. DOI URL
[24]	DIDENKO A N, KAPLUN V B, MALYSHEV Y F, et al. Lithospheric structure and Mesozoic geodynamics of the eastern Central Asian orogen[J]. Russian Geology and Geophysics, 2010, 51: 492-506. DOI URL
[25]	薛伟, 韩军. 多伦火山盆地核桃坝地区7-5 铀矿点沥青铀矿定年及其地质意义[J]. 矿物学报, 2013(增刊):270-271.
[26]	夏毓亮, 林锦荣, 朱辰杰, 等. 沽源—多伦地区火山岩类和花岗岩类同位素地质年代学及铀成矿条件研究[J]. 铀矿地质, 1998, 21(5): 274-281.

送样号	SiO₂	Al₂O₃	Fe₂O₃	FeO	CaO	MgO	K₂O	Na₂O	TiO₂	P₂O₅	MnO	烧失量	H₂O⁺	A/CNK	DI	AKI	Mg^#
YQ210	74.17	11.34	2.03	0.35	0.31	0.25	8.48	0.42	0.24	0.01	0.03	2.22	4.54	1.08	94.10	0.86	19.61
YQ223	72.92	11.14	1.90	0.32	0.16	0.18	8.48	2.02	0.26	0.01	0.01	2.51	4.31	0.87	92.95	1.11	15.80
YQ228	76.69	9.08	1.65	0.47	0.26	0.18	9.08	0.37	0.25	0.02	0.02	1.86	4.99	0.83	93.22	1.14	17.77
YQ499	75.64	10.31	1.76	0.43	0.40	0.29	8.28	0.37	0.17	0.01	0.05	2.16	4.83	1.00	94.65	0.92	24.61
YQ500	75.43	10.73	1.90	0.46	0.24	0.27	6.8	0.39	0.17	0.01	0.05	3.48	5.00	1.27	92.82	0.74	21.97
YQ529	74.80	10.73	1.92	0.48	1.13	0.52	7.00	0.54	0.25	0.01	0.02	2.58	4.71	1.02	89.84	0.78	34.92
2007/5/1	76.27	11.68	0.85	-	0.59	0.07	8.28	0.42	0.17	0.02	0.03	1.09	4.85	1.09	94.88	0.82	14.03
2007/5/2	70.09	13.25	4.09	-	0.77	0.62	5.28	4.04	0.33	0.07	0.06	1.31	3.55	0.96	90.67	0.93	23.09

送样号	SiO₂	Al₂O₃	Fe₂O₃	FeO	CaO	MgO	K₂O	Na₂O	TiO₂	P₂O₅	MnO	烧失量	H₂O⁺	A/CNK	DI	AKI	Mg^#
YQ210	74.17	11.34	2.03	0.35	0.31	0.25	8.48	0.42	0.24	0.01	0.03	2.22	4.54	1.08	94.10	0.86	19.61
YQ223	72.92	11.14	1.90	0.32	0.16	0.18	8.48	2.02	0.26	0.01	0.01	2.51	4.31	0.87	92.95	1.11	15.80
YQ228	76.69	9.08	1.65	0.47	0.26	0.18	9.08	0.37	0.25	0.02	0.02	1.86	4.99	0.83	93.22	1.14	17.77
YQ499	75.64	10.31	1.76	0.43	0.40	0.29	8.28	0.37	0.17	0.01	0.05	2.16	4.83	1.00	94.65	0.92	24.61
YQ500	75.43	10.73	1.90	0.46	0.24	0.27	6.8	0.39	0.17	0.01	0.05	3.48	5.00	1.27	92.82	0.74	21.97
YQ529	74.80	10.73	1.92	0.48	1.13	0.52	7.00	0.54	0.25	0.01	0.02	2.58	4.71	1.02	89.84	0.78	34.92
2007/5/1	76.27	11.68	0.85	-	0.59	0.07	8.28	0.42	0.17	0.02	0.03	1.09	4.85	1.09	94.88	0.82	14.03
2007/5/2	70.09	13.25	4.09	-	0.77	0.62	5.28	4.04	0.33	0.07	0.06	1.31	3.55	0.96	90.67	0.93	23.09

送样号	Rb	Ba	Th	U	Ta	Nb	La	Ce	Sr	Nd	Zr
KY-01	207.00	370.00	28.20	29.80	2.47	37.50	90.50	182.00	19.50	76.70	944.00
KY-02	249.00	428.00	25.50	25.50	2.13	33.20	105.00	201.00	19.30	84.10	717.00
KY-03	201.00	286.00	23.60	139.00	2.15	30.50	106.00	204.00	23.40	82.40	677.00
KY-04	225.00	368.00	24.30	363.00	1.99	31.50	90.90	171.00	17.70	72.10	693.00
KY-05	239.00	616.00	18.40	6.70	1.45	19.60	63.60	119.00	34.10	48.00	643.00
KY-06	216.00	578.00	18.20	966.00	1.66	24.00	48.20	99.00	14.10	51.00	551.00
KY-07	325.00	550.00	27.60	18.10	2.36	37.00	111.00	214.00	18.50	88.00	852.00
KY-08	259.00	390.00	25.60	32.50	2.14	32.50	103.00	189.00	22.40	82.20	686. 00
送样号	Hf	Sm	Y	Yb	Lu	Pr	Eu	Gd	Tb	Dy	Ho
KY-01	24.70	12.70	73.20	9.40	1.25	21.10	0.40	11.90	2.11	13.70	2.81
KY-02	19.50	13.20	62.10	7.44	1.07	23.80	0.52	11.90	2.05	10.90	2.26
KY-03	17.80	12.20	52.20	6.66	0.91	23.20	0.46	10.40	1.70	9.09	1.88
KY-04	18.10	11.40	58.50	6.57	0.96	20.20	0.40	10.90	1.91	10.20	1.95
KY-05	14.40	7.39	46.30	5.50	0.78	13.50	1.33	7.53	1.29	7.94	1.73
KY-06	13.60	9.02	55.40	5.48	0.82	12.40	0.36	9.12	1.57	9.37	1.87
KY-07	22.40	13.90	66.40	8.20	1.24	25.30	0.50	12.30	2.02	12.20	2.49
KY-08	18.80	11.90	61.70	7.57	1.05	23.00	0.50	10.50	1.85	11.50	2.18
送样号	Er	Tm	ΣREE	ΣLREE	ΣHREE	ΣLREE/ΣHREE		(La/Yb)_N		δEu	δCe
KY-01	8.53	1.28	434.38	383.40	50.98	7.52		6.51		0.10	0.95
KY-02	7.19	0.97	471.40	427.62	43.78	9.77		9.54		0.12	0.91
KY-03	6.15	0.83	465.88	428.26	37.62	11.38		10.76		0.12	0.93
KY-04	6.03	0.92	405.44	366.00	39.44	9.28		9.35		0.11	0.90
KY-05	5.29	0.77	283.65	252.82	30.83	8.20		7.81		0.54	0.91
KY-06	5.46	0.81	254.48	219.98	34.50	6.38		5.94		0.12	0.93
KY-07	7.64	1.20	499.99	452.70	47.29	9.57		9.15		0.11	0.92
KY-08	7.00	1.03	452.28	409.60	42.68	9.60		9.19		0.13	0.88

送样号	Rb	Ba	Th	U	Ta	Nb	La	Ce	Sr	Nd	Zr
KY-01	207.00	370.00	28.20	29.80	2.47	37.50	90.50	182.00	19.50	76.70	944.00
KY-02	249.00	428.00	25.50	25.50	2.13	33.20	105.00	201.00	19.30	84.10	717.00
KY-03	201.00	286.00	23.60	139.00	2.15	30.50	106.00	204.00	23.40	82.40	677.00
KY-04	225.00	368.00	24.30	363.00	1.99	31.50	90.90	171.00	17.70	72.10	693.00
KY-05	239.00	616.00	18.40	6.70	1.45	19.60	63.60	119.00	34.10	48.00	643.00
KY-06	216.00	578.00	18.20	966.00	1.66	24.00	48.20	99.00	14.10	51.00	551.00
KY-07	325.00	550.00	27.60	18.10	2.36	37.00	111.00	214.00	18.50	88.00	852.00
KY-08	259.00	390.00	25.60	32.50	2.14	32.50	103.00	189.00	22.40	82.20	686. 00
送样号	Hf	Sm	Y	Yb	Lu	Pr	Eu	Gd	Tb	Dy	Ho
KY-01	24.70	12.70	73.20	9.40	1.25	21.10	0.40	11.90	2.11	13.70	2.81
KY-02	19.50	13.20	62.10	7.44	1.07	23.80	0.52	11.90	2.05	10.90	2.26
KY-03	17.80	12.20	52.20	6.66	0.91	23.20	0.46	10.40	1.70	9.09	1.88
KY-04	18.10	11.40	58.50	6.57	0.96	20.20	0.40	10.90	1.91	10.20	1.95
KY-05	14.40	7.39	46.30	5.50	0.78	13.50	1.33	7.53	1.29	7.94	1.73
KY-06	13.60	9.02	55.40	5.48	0.82	12.40	0.36	9.12	1.57	9.37	1.87
KY-07	22.40	13.90	66.40	8.20	1.24	25.30	0.50	12.30	2.02	12.20	2.49
KY-08	18.80	11.90	61.70	7.57	1.05	23.00	0.50	10.50	1.85	11.50	2.18
送样号	Er	Tm	ΣREE	ΣLREE	ΣHREE	ΣLREE/ΣHREE		(La/Yb)_N		δEu	δCe
KY-01	8.53	1.28	434.38	383.40	50.98	7.52		6.51		0.10	0.95
KY-02	7.19	0.97	471.40	427.62	43.78	9.77		9.54		0.12	0.91
KY-03	6.15	0.83	465.88	428.26	37.62	11.38		10.76		0.12	0.93
KY-04	6.03	0.92	405.44	366.00	39.44	9.28		9.35		0.11	0.90
KY-05	5.29	0.77	283.65	252.82	30.83	8.20		7.81		0.54	0.91
KY-06	5.46	0.81	254.48	219.98	34.50	6.38		5.94		0.12	0.93
KY-07	7.64	1.20	499.99	452.70	47.29	9.57		9.15		0.11	0.92
KY-08	7.00	1.03	452.28	409.60	42.68	9.60		9.19		0.13	0.88