华北南缘古元古代末岩墙群侵位的磁组构证据

华北克拉通南缘的中条山及邻区广泛发育元古宙放射状基性岩墙群,与五台山-恒山和大同地区的北北西向基性岩墙群以及熊耳中条拗拉谷的火山岩在时空分布和地球化学方面均具有密切的相关性。中条山及邻区放射状基性岩墙群的宏观和微观流动构造(包括捕虏体、冲痕构造、矿物线理和定向斑晶)指示岩墙群以一定的仰角向北西侵位。通过该区岩墙群磁化率各向异性(AMS)测量得到磁组构的最大磁化率长轴优势方位分布图和磁组构各向异性特征分析进一步指示华北南缘古元古代末岩墙群从熊耳中条拗拉谷的底部向北西侵位。岩墙群的流动构造和磁组构的统计成果夯实了华北克拉通古元古代末基性岩墙群与熊耳中条拗拉谷的成生联系。     

晋北地区中元古代岩墙群的地球化学特征和大地构造背景

晋北地区发育大规模的中元古代北北西向岩墙群，未变形和未变质，是华北克拉通前寒武纪构造演化研究的最显著标志，根据本区岩墙群的岩石学和地球化学研究，这些岩墙群的岩石属于板内大陆裂谷玄武岩系列，形成于大陆裂谷拉张的构造环境，与东侧的燕辽－中条拗拉槽内的火山岩岩石化学对比分析，本区岩墙群的基性岩浆可能来自拗拉槽深部，这些基性岩浆从拗拉槽的深部向北西方向侵位于晋北地区先存的构造裂隙中形成了基性岩墙群。     

准噶尔盆地新生代构造应力对石炭纪火山岩构造裂缝发育的控制

构造裂缝的发育对改善储层的储渗条件有着重要的作用,特别是火山岩这种非传统储层,构造裂缝的发育是其成为有效储层的必要条件。本文主要借助构造应力场有限元数值模拟这一成熟的方法对准噶尔盆地石炭纪火山岩构造裂缝的发育状况进行预测。其两个主要的步骤是首先对区域构造应力场进行模拟计算,然后结合岩石的强度指标判断构造裂缝的发育状况。通过对准噶尔盆地地质背景和构造演化的分析,明确了新生代构造应力场的的决定性作用和石炭纪火山岩的分布区域(划分出六个区域),建立了数值模拟的计算模型、确定了边界条件与载荷。通过二维有限元数值模拟(应用Ansys软件)得到了新生代盆地应力场的分布特征和应力值。结合岩石强度指标,对火山岩构造裂缝(张裂缝和剪裂缝)的发育进行了预测并圈出相应的区域,主要为盆地西北缘、中央坳陷中部、滴西1东部,彩参2周缘、大井-将军庙等地区,对石炭纪火山岩的油气勘探战略选区, 优化勘探部署具有重要指导意义。     

PBDEs in the blubber of marine mammals from coastal areas of São Paulo, Brazil, southwestern Atlantic

Limited information is available in the literature on the levels of brominated flame retardants in the southern hemisphere. This study presents concentrations of polybrominated diphenyl ethers (PBDEs) in the blubber of small cetaceans from the coast of São Paulo (Brazil), southwestern Atlantic. PBDE levels were highest in Stenellafrontalis (770 ng g⁻¹ lipid) followed by Stenobredanensis (475 ng g⁻¹ lipid), Sotaliaguianensis (65.6 ng g⁻¹ lipid), Tursiopstruncatus (64.2 ng g⁻¹ lipid) and Pontoporiablainvillei (60.3 ng g⁻¹ lipid). In general, continental shelf individuals exhibited higher contamination than inshore animals. This might be related to larger prey items consumed by continental shelf dolphins. The pattern of contamination indicates that Penta-BDE commercial mixtures are a major source of PBDEs to top predators in the southwestern Atlantic. Congeners found in Octa-BDE formulations were not detected in the investigated animals.     

Levels of persistent organic pollutants and residual pattern of DDTs in small cetaceans from the coast of São Paulo, Brazil

The State of São Paulo is the most developed area in Brazil and was impacted by persistent organic pollutants for several decades. This study investigated organochlorines in five species of small cetaceans (Pontoporia blainvillei, Stenella frontalis, Sotalia guianensis, Tursiops truncatus and Steno bredanensis) found dead along the coast of São Paulo between 1997 and 2003. DDTs (15.9 μg g⁻¹ lipid; mean for all pooled individuals) and PCBs (8.08 μg g⁻¹) exhibited the highest concentrations in the animals, reflecting large amounts formerly used in Brazil. Lower levels of mirex (0.149 μg g⁻¹), HCB (0.051 μg g⁻¹), CHLs (0.008 μg g⁻¹) and HCHs (0.007 μg g⁻¹) were detected in all species. Residual pattern of DDTs in dolphins suggests that o,p′-DDT is more recalcitrant than p,p′-DDT in the body of the animals and/or the environment. In contrast to p,p′-DDT, residues of o,p′-DDT seem to be preferentially converted into o,p′-DDD rather than o,p′-DDE.