四川盆地普光气田上二叠统长兴组表生岩溶特征及意义*

四川盆地二叠系和三叠系的接触关系以及长兴组岩溶成因的认识,地质界一直存在较大分歧。通过野外露头、钻井、岩心、成像测井、C-O同位素等资料研究发现,普光气田长兴组发育大规模溶沟、溶洞、囊状溶洞、岩溶角砾岩;P/T界线附近长兴组溶蚀灰岩碳同位素发生严重负偏移;长兴组顶见不整合面,成像测井岩溶相带划分明显;长兴组顶部存在地层缺失。综合分析认为,普光气田长兴组发生过表生岩溶作用,长兴阶晚期重大海退事件是引起表生岩溶的主要因素。长兴组长期接受表生岩溶作用的改造,除形成台地边缘礁滩相储集层外,在礁滩欠发育的台地内部和台地前缘上斜坡等区带,是寻找不整合岩溶储集层的有利地区。     

辽东王家堡子地区古元古代花岗岩地球化学特征、锆石U-Pb年龄、Hf同位素及其地质意义

辽东王家堡子地区出露大量古元古代花岗质岩石,前人将其统称为花岗质混杂岩。通过详细的野外地质调查和室内综合研究,将该套花岗质混杂岩解体为条痕状黑云母二长花岗岩和片麻状黑云母二长花岗岩两类。岩石地球化学分析结果显示二者具有一致的地球化学特征。均显示高SiO_2、富K_2O、贫Al_2O_3的特征,K_2O/Na_2O=0.64～2.14,TiO_2含量为0.16%～0.3%,MnO、MgO、CaO和P_2O_5的含量较低,铝指数A/CNK集中分布在1.06～1.1之间,A/NK在1.50～1.62之间,均属于过铝质高钾钙碱性系列;微量元素显示强烈亏损Nb、Ti、Ta等高场强元素,富集Rb、U、K等大离子亲石元素,具有明显的负Eu异常,具有A型花岗岩的特征。条痕状黑云母二长花岗岩大部分锆石为具有清晰振荡环带的岩浆锆石,LA-ICP-MS锆石U-Pb年龄为2188±13Ma,代表该岩石的岩浆结晶年龄。片麻状黑云母二长花岗岩大部分锆石具有明显的变质增生边,部分核部锆石具有清晰的振荡环带,LA-ICP-MS锆石U-Pb测年获得核部年龄为2214±16Ma,代表该岩石的岩浆结晶年龄;增生边年龄为1905±13Ma,应代表该岩石的变质年龄。条痕状黑云母二长花岗岩和片麻状黑云母二长花岗岩的Hf同位素模式年龄分别为2387～2584Ma和2474～2641Ma,平均地壳模式年龄分别为2495～2808Ma和2633～2868Ma,大于岩石形成年龄,暗示研究区古元古代花岗岩源区主要为太古宙基底,混有少量古元古代新生地壳。结合前人报道的埃达克质花岗闪长岩的形成环境,认为胶-辽-吉古元古代造山/活动带早期经历了2.2～2.15Ga的拉伸裂解过程和2.0Ga左右俯冲挤压的构造演化过程。     

科马提岩与苦橄岩的区别及对若干晚古生代“科马提岩”的质疑

以往学术界更多的关注科马提岩和苦橄岩的相似性,忽略其差异。通过全数据模式,采集数据库内全球的太古宙科马提岩、后太古宙低/高钛苦橄岩数据,对比三者之间的差异发现,科马提岩更富MgO、Cr、Ni、Cs、Pb、Co和Zn,其次为低钛苦橄岩(除Co和Zn),其余主量、微量元素的含量由高至低依次为高钛苦橄岩、低钛苦橄岩、科马提岩。依据元素间的差异(如Cr/Ga、MgO/Ga、MnO/Zr、Cr/Zr等),采用密度分布函数(Density Distribution)在Matlab软件中绘制出可有效区分3类岩石的等密度判别图,并用该图对若干晚古生代"科马提岩"的岩性重新厘定。结合岩相学和地球化学特征研究表明,晚古生代"科马提岩"中,印度东部为高钛苦橄岩,越南为化学成分与科马提岩类似的低钛苦橄岩,印度拉达克地区为低钛苦橄岩。     

内蒙古东乌旗葛根敖包石英闪长岩岩体年代学、地球化学及其地质意义

内蒙古东乌旗地区新近发现的葛根敖包铅锌矿,成矿与赋矿岩体石英闪长岩关系密切,对石英闪长岩进行系统的LAICP-MS锆石U-Pb定年及锆石Hf同位素分析,并对石英闪长岩进行主量、微量和稀土元素分析。锆石U-Pb定年结果显示,石英闪长岩2个样品的锆石U-Pb年龄分别为299±1Ma和301±1Ma,均为晚石炭世。岩石主量、微量及稀土元素分析显示,石英闪长岩具有典型的富硅、富碱特征,Na_2O/K_2O值为1.14～1.93,平均1.39,明显富钠高钾,属高钾钙碱性系列;铝饱和指数A/CNK值为0.79～0.95,为准铝质或铝不饱和花岗岩类;轻、重稀土元素分馏显著,球粒陨石标准化稀土元素配分模式表现为明显的右倾,显示岩浆源区可能有石榴子石残留;并有微弱负Eu异常,δEu=0.80～0.91,δCe=0.89～0.96,均靠近1,指示源区无斜长石残留;同时具低Sr、高Yb特征;并指示高场强元素U、La、Nd、Zr相对富集,而Th、Nb、Sr、P、Ti相对亏损,且大离子亲石元素Rb、Ba、K相对富集,Nb/Ta值低,指示岩浆源区可能为幔源为主。锆石Hf同位素分析显示,εHf(t)值全部为正值,+10.8～+13.6(全部大于10,较高),TDM2介于440～629Ma之间,相对集中,明显大于其锆石U-Pb年龄,其年轻的TDM2年龄和较高的εHf(t)值表明,岩浆中有相当大的幔源物质的贡献。结合区域构造演化,认为葛根敖包石英闪长岩岩浆源区可能为亏损地幔物质部分熔融并在上升过程中受到少量壳源物质的混染,为活动陆缘弧环境的产物。     

Zircon U-Pb-Hf constraints from Gongga Shan granites on young crustal melting in eastern Tibet

The Gongga Shan batholith is a complex granitoid batholith on the eastern margin of the Tibetan Plateau with a long history of magmatism spanning from the Triassic to the Pliocene. Late Miocene-Pliocene units are the youngest exposed crustal melts within the entire Asian plate of the Tibetan Plateau.Here, we present in-situ zircon Hf isotope constraints on their magmatic source, to aid the understanding of how these young melts were formed and how they were exhumed to the surface. Hf isotope signatures of Eocene to Pliocene zircon rims(ε_Hf(t)=-4 to +4), interpreted to have grown during localised crustal melting, are indicative of melting of a Neoproterozoic source region, equivalent to the nearby exposed Kangding Complex. Therefore, we suggest that Neoproterozoic crust underlies this region of the Songpan-Ganze terrane, and sourced the intrusive granites that form the Gongga Shan batholith. Localised young melting of Neoproterozoic lower or middle crust requires localised melt-fertile lithologies. We suggest that such melts may be equivalent to seismic and magnetotelluric low-velocity and high-conductivity zones or "bright spots" imaged across much of the Tibetan Plateau. The lack of widespread exposed melts this age is due either to the lack of melt-fertile rocks in the middle crust, the very low erosion level of the Tibetan plateau, or to a lack of mechanism for exhuming such melts. For Gongga Shan, where some melting is younger than nearby thermochronological ages of low temperature cooling, the exact process and timing of exhumation remains enigmatic, but their location away from the Xianshuihe fault precludes the fault acting as a conduit for the young melts. We suggest that underthrusting of dry granulites of the lower Indian crust(Archaean shield) this far northeast is a plausible mechanism to explain the uplift and exhumation of the eastern Tibetan Plateau.     

Paleoproterozoic volcanic rocks in the southern margin of the North China Craton,central China:Implications for the Columbia supercontinent

The volcanic rocks of the Xiong'er Group are situated in the southern margin of the North China Craton(NCC).Research on the Xiong er Group is important to understand the tectonic evolution of the NCC and the Columbia supercontinent during the Paleoproterozoic.In this study,to constrain the age of the Xiong'er volcanic rocks and identify its tectonic environment,we report zircon LA-ICP-MS data with Hf isotope,whole-rock major and trace element compositions and Sr-Nd-Pb-Hf isotopes of the volcanic rocks of the Xiong'er Group.The Xiong'er volcanic rocks mainly consist of basaltic andesite,andesite.dacite and rhyolite,with minor basalt.Our new sets of data combined with those from previous studies indicate that Xiong'er volcanism should have lasted from 1827 Ma to 1746 Ma as the major phase of the volcanism.These volcanics have extremely low MgO.Cr and Ni contents,are enriched in LREEs and LILEs but depleted in HFSEs(Nb,Ta,and Ti),similar to arc-related volcanic rocks.They are characterized by negative zircon ε_(Hf)_(t) values of-17.4 to 8.8,whole-rock initial ~(87)Sr/~(86)Sr values of 0.7023 to 0.7177 andε_(Nd)(t) values of-10.9 to 6.4.and Pb isotopes(~(206)Pb/~(204)Pb =14.366-16.431,~(207)Pb/~(204)Pb =15.106-15.371,~(208)Pb/~(204)Pb= 32.455-37.422).The available elemental and Sr-Nd-Pb-Hf isotope data suggest that the Xiong'er volcanic rocks were sourced from a mantle contaminated by continental crust.The volcanic rocks of the Xiong'er Group might have been generated by high-degree partial melting of a lithospheric mantle that was originally modified by oceanic subduction in the Archean.Thus,we suggest that the subduction-modified lithospheric mantle occurred in an extensional setting during the breakup of the Columbia supercontinent in the Late Paleoproterozoic,rather than in an arc setting.     

覆盆子-红花药对与男性不育症的治疗相关机制探讨

目的：基于网络药理学探讨覆盆子-红花药对治疗男性不育症的物质基础及作用机制。方法：用TCMSP数据库检索覆盆子、红花,收集其化学成分以及靶点信息;用GeneCards和OMIM数据库筛选男性不育症的疾病靶点;应用韦恩图筛选药物与疾病的共同靶点;应用R软件进行GO富集分析及KEGG分析;应用 Cytoscape 3.7.2 软件构建药物-活性成分-疾病-靶点互作网络。结果：从覆盆子、红花得到了22个活性成分及202个药物靶点。在药物-活性成分-疾病-靶点互作网络中,degree值较高的为槲皮素及木犀草素,表明覆盆子-红花药对治疗男性不育症的主要活性成分可能为槲皮素、木犀草素等。覆盆子-红花药对治疗男性不育症的可能靶点有131个,其中核心靶点为ALB、AKT1、IL-6、VEGFA、JUN等,这些靶点主要与氧化及抗氧化生物等生物学过程相关。覆盆子-红花药对的靶点主要通过P13K/Akt信号通道治疗男性不育症。结论：覆盆子-红花药对通过多靶点、多途径治疗男性不育症。本研究为开展覆盆子-红花药对治疗男性不育症的实验提供了理论基础,为男性不育症的治疗提供了更多的思路。     

Evaluation of riverbed magnetic susceptibility for mapping biogeochemical hot spots in groundwater-impacted rivers

Redox hot spots occurring as metal-rich anoxic groundwater discharges through oxic wetland and river sediments commonly result in the formation of iron (Fe) oxide precipitates. These redox-sensitive precipitates influence the release of nutrients and metals to surface water and can act as ‘contaminant sponges’ by absorbing toxic compounds. We explore the feasibility of a non-invasive, high-resolution magnetic susceptibility (MS) technique to efficiently map the spatial variations of magnetic Fe oxide precipitates in the shallow bed of three rivers impacted by anoxic groundwater discharge. Laboratory analyses on Mashpee River (MA, USA) sediments demonstrate the sensitivity of MS to sediment Fe concentrations. Field surveys in the Mashpee and Quashnet rivers (MA, USA) reveal several discrete high MS zones, which are associated with likely anoxic groundwater discharge as evaluated by riverbed temperature, vertical head gradient, and groundwater chemistry measurements. In the East River (CO, USA), widespread cobbles/rocks exhibit high background MS from geological ferrimagnetic minerals, thereby obscuring the relatively small enhancement of MS from groundwater induced Fe oxide precipitates. Our study suggests that, in settings with low geological sources of magnetic minerals such as lowland rivers and wetlands, MS may serve as a complementary tool to temperature methods for efficiently mapping Fe oxide accumulation zones due to anoxic groundwater discharges that may function as biogeochemical hot spots and water quality control points in gaining systems.     

Modelling the internal stress field in argillaceous rocks under humidification/desiccation

This paper deals with analytical and numerical modelling of the internal stress generated in argillaceous rocks during humidification/desiccation processes, which is an essential issue for damage study. This local stress field arises from two mechanisms: (i) complex interactions between free swelling/shrinking clay matrix and non‐strained inclusions of carbonate and quartz and (ii) a self‐restraint effect induced by the moisture gradient during the transient moisture exchange process. The inclusion–matrix interaction is investigated in different cases. Firstly, the analytical solution of the stress around a cylindrical inclusion embedded in an infinite swelling matrix is derived: The inclusion would suffer tension (compression) under humidification (desiccation), and the resulting cracking patterns are discussed. Then, the problem of two inclusions with different distances in an infinite swelling matrix is considered, and it is shown that the local stress around an inclusion will be perturbed and amplified by neighbouring inclusions. Finally, an inclusion outcropping at the free surface of a swelling matrix is modelled as to investigate the effect of free surface: The inclusion–matrix interface undergoes shear stresses of which the maximum is found at the free surface. In addition to the inclusion–matrix interaction, the self‐restraint effect is investigated: The induced stress is maximal at the beginning of humidification/desiccation processes and vanishes gradually with time. The quantity of the self‐restraint stress is strongly controlled by the hydric loading rate. Copyright © 2014 John Wiley & Sons, Ltd.     

Chloride source delineation in an urban-agricultural watershed: Deicing agents versus agricultural contributions

Analyses (n = 525) of chloride (Cl⁻), bromide (Br⁻), nitrate as nitrogen (NO₃-N), sodium (Na⁺), calcium (Ca²⁺) and potassium (K⁺) in stream water, tile-drain water and groundwater were conducted in an urban-agricultural watershed (10% urban/impervious, 87% agriculture) to explore potential differences in the signature of Cl⁻ originating from an urban source as compared with an agricultural source. Only during winter recharge events did measured Cl⁻ concentrations exceed the 230 mg/L chronic threshold. At base flow, nearly all surface water and tile water samples had Cl⁻ concentrations above the calculated background threshold of 18 mg/L. Mann–Whitney U tests revealed ratios of Cl⁻ to Br⁻ (p = .045), to NO₃-N (p < .0001), to Ca²⁺ (p < .0001), and to Na⁺ (p < .0001) to be significantly different between urban and agricultural waters. While Cl⁻ ratios indicate that road salt was the dominant source of Cl⁻ in the watershed, potassium chloride fertilizer contributed as an important secondary source. Deicing in watersheds where urban land use is minimal had a profound impact on Cl⁻ dynamics; however, agricultural practices contributed Cl⁻ year-round, elevating stream base flow Cl⁻ concentrations above the background level.