Geochemistry and geodynamic significance of the rare-earth mineralized Paleoproterozoic Longwangzhua

来源 :Chinese Journal of Geochemistry | 被引量 : 0次 | 上传用户:WYQ1987412
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The Longwangzhuang granite pluton occurs on the southern margin of the North China Craton and consists mainly of biotite syenogranite with aegirine granite being locally distributed.The granites are characterized by high silicon and alkaline contents(SiO2=72.17%-76.82%,K2O+Na2O=8.28%-10.22%,K2O/Na2O>>1),AI(agpaitic index) =0.84-0.95,DI=95-97,ASI(aluminum saturation index)=0.96-1.13,and very high Fe* number(FeO*/(FeO*+Mg)=0.90-0.99),thus the granites are assigned to the metaluminous to weakly peraluminous,alkalic to calc-alkalic ferroan A-type granites.The granites are rich in large ion lithophile elements(LILE),especially high in REE concentrations(REE+Y=854×10-6-1572×10-6);whereas the enrichment of high strength field elements(Nb,Ta,Zr,Hf) is obviously less than that of LILEs,exhibiting mild depletions on trace element spider plots;and the rocks are significantly depleted in Ba,Sr,Ti,and Pb.The low εNd(t) values(-4.5--7.2) and high model ages(2.3-2.5 Ga) of the granites as well as the low εHf(t) values(-1.11--5.26) and high Hf model ages(THf1= 2.1-2.3 Ga,THf2=2.4-2.6 Ga) of zircons from the biotite syenogranite suggest that the granites were probably derived from an enriched mantle source.The zircons from the biotite syenogranite are mainly colorless transparent crystals exhibiting well-developed oscillatory zoning on the cathodoluminescence images with a LA-ICPMS zircon U-Pb age of 1602.1±6.6 Ma(MSWD=0.48).Petrochemical,trace elements,as well as Nd and Hf isotopic compositions of the rocks demonstrate that the granites were formed in a within-plate extensional tectonic regime possibly related to the breakup of the Columbia supercontinent.The granites were most likely formed through extreme fractional crystallization of alkali basaltic magma resulted from partial melting of the mantle,which was fertilized by recycling crustal rocks triggered by the delamination of lithospheric mantle and lower crust following the ~1.8 Ga collision and amalgamation of the North China Craton which is part of the Columbia supercontinent.However,contamination of neo-Archean to Paleoproterozoic crustal rocks during the ascent and emplacement of the magma could not be excluded.Being the youngest known anorogenic magmatism on the southern margin of the North China Craton related to Columbia breakup,it might represent the break off of the North China Craton from Columbia supercontinent at the end of Paleoproterozoic. The Longwangzhuang granite pluton occurs on the southern margin of the North China Craton and consists primarily of biotite syenogranite with aegirine granite being locally distributed. The granites are characterized by high silicon and alkaline contents (SiO2 = 72.17% -76.82%, K2O + Na2O = 8.28% -10.22%, K2O / Na2O >> 1), AI (agaistatic index) = 0.84-0.95, DI = 95-97, aluminum saturation index = 0.96-1.13, and very high Fe * number (FeO * /(FeO*+Mg)=0.90-0.99), thus the granites are assigned to the metaluminous to weakly peraluminous, alkalic to calc-alkalic ferroan A-type granites.The granites are rich in large ion lithophile elements (LILE), especially high in REE concentrations (REE + Y = 854 × 10 -6 - 1572 × 10 -6); while the enrichment of high strength field elements (Nb, Ta, Zr, Hf) is obviously less than that of LILEs, exhibiting mild depletions on trace element spider plots; and the rocks are significantly depleted in Ba, Sr, Ti, and Pb. low εNd (t) values ​​(-4.5-7.2) and high model ages (2.3-2.5 Ga) of the granites as well as the low εHf (t) values ​​(-1.11-5.26) and high Hf model ages (THf1 = 2.1-2.3 Ga, THf2 = 2.4-2.6 Ga) of zircons from the biotite syenogranite suggest that the granites were probably derived from an enriched mantle source. The zircons from the biotite syenogranite are mainly colorless transparent crystals exhibiting well-developed oscillatory zoning on the cathodoluminescence images with a LA-ICPMS zircon U-Pb age of 1602.1 ± 6.6 Ma (MSWD = 0.48) .Petrochemical, trace elements, as well as Nd and Hf isotopic compositions of the rocks demonstrate that the granites were formed in a within-plate extensional tectonic regime may related to the breakup of the Columbia supercontinent. the granites were most likely formed through the extreme fractional crystallization of alkali basaltic magma resulted from partial melting of the mantle, which was fertilized by recycling crustal rocks triggered by the delamination of lithospheric mantle and lower crust following the ~ 1.8 Ga collision and amalgamation of the Nor th China Craton which is part of the Columbia supercontinent. However, contamination of neo-Archean to Paleoproterozoic crustal rocks during the ascent and emplacement of the magma could not be excluded. being the youngest known anorgenic magmatism on the southern margin of the North China Craton related to Columbia breakup, it might represent the break off of the North China Craton from Columbia supercontinent at the end of Paleoproterozoic.
其他文献
实达网络公司根据多年对教育行业的了解和认知,提出适合中国国情的,技术先进的教育城域网解决方案。该方案立足于建立连接中学、小学和教育主管部门的宽带城域网,完成多路实
为克服过去统计调查分析服务中孤军作战的弊端,进一步提高服务水平,发挥统计在科学决策中的参谋,助手作用,该局于4月中旬成立了综合平衡、农村经济、工交投资和商贸流通四个
“来来来,都进场了……”监考老师站在考场门口大声招呼着,“快点儿快点儿,再晚就不让进了……”  “天哪,如果考不好怎么办?”  “我还没背好呢!”  “啊,上帝保佑,菩萨保佑,一定要让我考好历史啊……”  周围一片聒噪声,顾歆神色平静地走进考场,脑中还回想着刚才背的一个知识点:唉……罗斯福新政的最后一条是什么来着?是什么来着?坏了坏了,是什么来?怎么忘了呢?考这个怎么办……  她有些慌乱了,刚想再
**IT0RIN.**IE刀Zhen YAOIDshtute of BbCbem1Stry and Cu B10bgy,Sh—gbdlush-tutes for Biological Sciences,Chinese Academp of Sciences,320 Yueyang Road,Shanghai 200031;
尊敬的中国牧业通讯杂志社暨唐福坤社长: 我是湖北省谷城县畜牧局的一名年轻技术干部,有12年的基层工作经历,先后从事过动物防疫、动物从检疫及兽医卫生监督等工作。多年来,
朋友是什么?是能让你一天都过得快乐、充实的人。我的身边就有这样一位朋友,她叫张辰雨。去年六月的一天,我们在同一个“小饭桌”吃午饭。中午没事可做,我们就看看书、看看电
介绍了利用SIMATIC-NET实现西门子最新推出的41X-5H集成PN口的冗余PLC同上位机WINCC之间通过普通网卡建立以太网连接的方法,保证WINCC能不间断监控PLC的运行状态同时,降低了
目的探讨偏头痛患者脑血管血流动力学变化。方法采用脑血管血流动力学分析仪对63例偏头痛患者进行脑血管血流动力学检测。结果偏头痛患者脑血流速度、流量明显减少,外周阻力
梁启超先生在被切除右肾肿瘤后,却被发现病变实在左肾。一时间,初人中国的西医饱受质疑。而梁先生却希望国人不要以他的病为口实,以塞中国医学之前途。这正是一种长远的眼光
目的用SonoCT技术检查脑梗死病人的颈动脉粥样硬化改变及其相关性。方法对80例脑梗死病人的颈动脉进行SonoCT技术检查,观察其有无斑块、斑块性质、IMT增厚、狭窄,测量PSV、ED