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| 1 | 内蒙古狼山西北缘乌兰敖包地区“阿木山组”沉积时限、物源特征及其地质意义显示文摘沉积盆地的研究对于理解造山带的构造演化具有重要意义.内蒙古狼山地区位于中亚造山带中段,构造演化历史复杂,晚古生代沉积盆地的大地构造背景存在争议.在对狼山西北缘乌兰敖包地区出露的'阿木山组'岩性特征、沉积构造及沉积环境的系统研究基础上,将该组分为3个岩性段.一段主要为粗碎屑岩,交错层理发育,沉积环境为辫状河三角洲;二段底部主要为粗碎屑岩,向上沉积物粒度变细,顶部出现生物碎屑灰岩,在岩屑石英砂岩中新发现芦木Calamites sp.,座延羊齿Alethopteris sp.,带科达Cordaites principalis Gein等植物化石,沉积环境由辫状河三角洲向滨海环境过渡;三段主要岩性为结晶灰岩,含生物碎屑,沉积环境为滨-浅海环境.'阿木山组'一、二段砂岩碎屑锆石年龄可分为~2.5Ga、~1.8~1.2Ga、~826Ma、461~440Ma和313~273Ma五个时间段,其中最小年龄为273Ma,结合植物化石鉴定结果以及上覆火山岩地层年代,确定'阿木山组'沉积时代为265~273Ma.研究区内同时代的岩浆岩指示该区在早中二叠世处于古亚洲洋向华北板块俯冲的岩浆弧环境,结合'阿木山组'的沉积特征、沉积时代及所处构造位置,对其地层划分与对比方案提出建议. | 郭硕 滕学建 刘洋 滕飞 何鹏 田健 王文龙 段霄龙 | 2019 | 地球科学2019，44，1： | 7 |
| 2 | Nature and evolution of the lithospheric mantle revealed by water contents and He-Ar isotopes of peridotite xenoliths from Changbaishan and Longgang basalts in Northeast China显示文摘The nature and evolution of the lithospheric mantle underlying Northeast(NE)China were investigated by assessing the mineral chemistry,water contents,and noble gas(He-Ar)isotopes of peridotite xenoliths captured by Cenozoic basalts from the Changbaishan and Longgang regions.The xenoliths,which have863–1141℃ equilibration temperatures,primarily comprise spinel lherzolites and rare spinel harzburgites.The Mg#(Fo)values of olivine in the peridotite xenoliths vary from 86.9 to 91.3.The clinopyroxenes have high Ti/Eu and low(La/Yb)N,and their chondrite-normalized rare earth elements(REEs)exhibit light REE-depletion to-enrichment patterns,indicating that the mantle underneath the investigated region was predominantly subjected to partial melting(1%–10%)and was metasomatized by silicate melts.The measured3He/4He ratios of the Changbaishan xenoliths have a narrow range from 5.8 Ra to 8.4 Ra with an average of 7.4 Ra.The3He/4He isotopic ratios of the Longgang xenoliths varied from 4.7 Ra to8.1 Ra with an average of 5.9 Ra;slightly lower than the Changbaishan xenoliths.The whole-rock H2Ocontents of the studied peridotite ranged from 9 to 132 ppm.The high H2O contents in excess of50 ppm(up to 132 ppm)might represent newly accreted and cooled asthenospheric materials,while those with H2O contents lower than 50 ppm(as little as 9 ppm)may represent thinned,relic,ancient lithospheric mantle.These geochemical evidences,in combination with published data,indicated that the lithospheric mantle beneath the Changbaishan and Longgang in NE China is dominated by the younger and more fertile lithospheric mantle with a minor ancient and refractory keel.In addition,the lithospheric mantle of this area was metasomatized by melts related to the recent subduction event(e.g.,Pacific oceanic plate).Therefore,the westward-dipping Pacific oceanic plate subduction had an important contribution to the transformation of the lithospheric mantle beneath NE China. | Qinghu Xu Jiaqi Liu Huaiyu He Yunhui Zhang | 2019 | Science Bulletin2019，64，18： | 4 |
| 3 | 冀北崇礼红旗营子岩群中镁铁质岩石地球化学和年代学研究:对华北克拉通新太古代晚期-古元古代早期大地构造演化的启示显示文摘崇礼地区红旗营子岩群位于华北克拉通北缘,该区红旗营子岩群的岩石组合、构造属性及时代归属对于探讨华北克拉通新太古代晚期-古元古代早期大地构造演化具有重要意义.本文对崇礼地区红旗营子岩群中的镁铁质岩石进行了野外、镜下岩相学、全岩地球化学、锆石U-Pb年代学及Hf同位素分析,并讨论其对华北克拉通北缘新太古代晚期-古元古代早期地壳演化的指示意义.研究区红旗营子岩群中的镁铁质岩石以夹层产出于表壳岩中,主要由斜长角闪岩和斜长辉石角闪岩组成.红旗营子镁铁质岩石主量元素中SiO2(40.17%~51.53%)、Na2O(1.52%~3.47%)和K2O(0.43%~1.23%)含量范围较大,具有较高的CaO(9.15%~12.68%)、MgO(5.90%~13.36%)和Al2O3(9.81%~20.92%)含量.镁铁质岩石轻稀土元素轻微富集,重稀土元素配分模式近平坦,大离子亲石元素Ba、U、K、Sr富集,高场强元素Th、Nb、Ta、Ti明显亏损.斜长角闪岩LA-ICPMS锆石U-Pb测年显示207Pb/206Pb加权平均年龄为2 477±23 Ma(MSWD=3.1),上交点年龄为2 468±22 Ma,表明其形成于新太古代晚期-古元古代早期.斜长角闪岩锆石Hf同位素分析结果显示εHf(t)为负值(-5.2~0),一阶段模式年龄(TDM1)为2 673~2 783 Ma,二阶段模式年龄(TDM2)为2 880~3 074 Ma,均大于锆石的形成年龄,指示其来源于古老地壳物质的再循环.镁铁质岩石全岩地球化学分析结果显示其形成于岛弧相关环境.结合华北其他地区研究成果,本研究表明崇礼地区新太古代晚期-古元古代早期可能发生了一期与岛弧有关的岩浆事件. | 陶光活 李晓峰 王军鹏 蒋康 | 2020 | 地球科学2020，45，9： | 2 |
| 4 | Late Triassic–Cenozoic Thermochronology in the Southern Sanjiang Tethys, SW China, New Insights from Zircon Fission Track Analysis显示文摘The Sanjiang Tethys orogenic belt is located in the southeast side of the Qinghai-Tibet Plateau. It has undergone the opening and closing movements in different periods of Tethys oceans, complex accretive orogeny and strong mineralization from Paleozoic to Mesozoic. Using zircon fission track(ZFT) thermochronology, this study reveals the Sanjiang Tethys has experienced multi-stage tectonic activities during the Late Triassic–Cenozoic. The 15 ZFT ages with their decomposition components obtained from Sanjiang Tethysian region range from 212 to 19 Ma, which not only shows 6 age groups of 212, 179–172, 156–133, 121–96, 84–70 and 50–19 Ma, but also constrains the age limit of the tectonothermal events. These age groups recorded the Paleo-Tethys main and branches ocean opening/closure time. The age-elevation plot indicates the Sanjiang region had differential uplifting and exhumation and fast uplifting times of ca. 133, 116 and 80 Ma, coinciding with the age groups mentioned above. These results show new geochronological evidences and viewpoints. | Li Yang Wanming Yuan Xiaoyong Zhu Zhen Shi | 2019 | Journal of Earth Science2019，30，5： | 2 |
| 5 | Mineral Chemistry of Biotite and Its Petrogenesis Implications in ca.2.5 Ga Wangjiazhuang Granitic Pluton,North China Craton显示文摘The Wangjiazhuang granitic pluton is located in the central Zanhuang Domain,the central part of the North China Craton,which is mainly composed of biotite monzogranite with few mafic microgranular enclaves.Biotite is an important ferromagnesian mineral in most of the intermediatefelsic igneous rocks,and its mineral chemistry can record the properties of magma and the petrogenetic physicochemical conditions.In this study,we carried out a detailed petrographic study by electric probe microanalysis on biotite for the biotite monzogranite and mafic microgranular enclaves,to discuss the source,physicochemical conditions,and the magma mingling/mixing processes of the Wangjiazhuang granite.The results show significantly different chemical compositions from the biotite monzogranite and mafic microgranular enclaves.The crystallization of these biotite grains from the biotite monzogranite and mafic microgranular enclaves all occurred in low oxygen fugacity.The biotite grains in biotite monzogranite are rich in Fe,poor in Mg,which belong to siderophyllite.The ratios of[(Fe^(3+)+Fe^(2+))/(Fe^(3+)+Fe^(2+)+Mg2+)]are between 0.78 and 0.86.The average of FeOT(total FeO)/MgO of biotite grains in biotite monzogranite is 9.02.The MF values[2×Mg/(Fe^(2+)+Mg+Mn)]of biotite monzogranite are between 0.31 and 0.47,suggesting biotite monzogranite derived from crustal source rocks(metasedimentary rocks).The formation of granitic rocks including the Wangjiazhuang granite was related to the subduction event at ca.2.5 Ga which resulted in the melting event,and then induced the early partial melting of TTGs and metasedimentary rocks.The biotite in mafic microgranular enclaves varies from siderophyllite to ferrobiotite,and MF values range from 0.63 to 1.06,suggesting that magma of mafic microgranular enclaves had experienced magma mixing/mingling in various degrees.Biotite monzogranite and parts of mafic microgranular enclaves have a similar crystallized condition,while other mafic microgranular enclaves are different from biotite monzogranite.The differences between biotite monzogranite and mafic microgranular enclaves may be a consequence of continuous interaction between granitic and mafic magmas. | Junpeng Wang Kang Jiang Deng Xiao Fenfang Li Fupeng Li Xiaofeng Li Song Jin Guanghuo Tao | 2022 | Journal of Earth Science2022，33，6： | 1 |
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