苏北盆地中—古生界海相烃源岩发育规律及其意义

苏北盆地与南黄海盆地属于同一构造单元,苏北盆地的烃源岩发育规律的研究对南黄海油气勘探具有重要启示意义。在野外地质研究和69个烃源岩实测数据的基础上,结合已有分析化验数据及油气勘探资料,对苏北盆地的中—古生界海相烃源岩厚度分布和地球化学特征进行了分析,结果表明烃源岩整体沿北东向展布,在中—古生界均存在多个烃源岩发育中心,并明显有向南黄海海域延伸的趋势;下古生界普遍比上古生界的热演化程度高,并具有区域不均一性,二叠系的热演化程度相对较低,存在二次生烃的潜力。苏北盆地在中—古生界海相地层烃源岩特征的研究,进一步揭示了南黄海盆地具有良好的油气勘探潜力。     

松辽盆地深层断陷沙河子组烃源岩分布预测与生气潜力

松辽盆地下白垩统沙河子组是深层断陷的主要烃源岩发育层系,目前钻井揭示其厚度大(700 m),埋藏深(3 500 m),但钻井大都分布于深层断陷的边部,断陷内部烃源岩层揭示少。根据断陷结构样式及地震反射特征,总结出单断箕状断陷和双断地堑式断陷两种沙河子组烃源岩发育模式,并确定深层烃源岩主要有五种存在形式。断陷中部席状平行结构、成层性、连续性好的地震反射特征的烃源岩最为落实,主要为深湖--半深湖相,暗色泥岩厚度大,暗地比高(45%~70%)。深层沙河子组烃源岩总生气量约148.38×1012m3,天然气资源潜力巨大。     

Re-Os同位素在沉积地层精确定年及古环境反演中的应用进展

Re-Os同位素亲有机质的性质,使得富有机质沉积岩在沉积的过程中能够吸附富集海水中的Re、Os,沉积岩的沉积压实过程也是其中Re-Os同位素体系封闭计时的过程,沉积岩Re-Os同位素等时线年龄代表地层沉积时代,Os同位素初始比值187Os/188Os反映沉积时海水的Os同位素比值。Re-Os同位素体系在富有机质沉积岩中的成功应用,能够直接确定地层沉积时代,从而对地层界线进行直接厘定,并且能够对一些沉积矿床形成时代、冰川事件发生时代进行厘定和限制。通过沉积岩Re-Os同位素特征,可以对古环境进行反演,有助于了解全球大气海洋的演化,气候的变化,对研究生物灭绝等重大地质事件发生的时限和机制以及金属矿床的成矿物质来源具有重要意义。文章阐述了Re-Os同位素在富有机质沉积岩中应用的原理,并列举了Re-Os同位素在沉积地层精确定年及古环境反演中应用实例,说明了富有机质沉积岩Re-Os同位素分析精度及其影响因素,以使Re-Os同位素体系作为一种强有力的工具,解决更多的沉积地层时代问题以及更好地对古环境进行反演。     

冀中坳陷东北部石炭-二叠系烃源岩热史及成熟史模拟

石炭-二叠系煤成气藏是冀中坳陷东北部亟待突破的勘探领域。文中基于大量的钻井、测井、地球化学和古地温资
料,分别模拟构建了大城凸起、文安斜坡和武清凹陷的埋藏史和考虑岩浆热液侵入作用的热演化史。研究结果表明冀中坳
陷东北部石炭-二叠系地层总体上经历了“三沉两抬”的构造演化过程,在印支运动前全区具有近似的演化历史,印支
期、燕山期区内构造演化开始分异,至新生代形成总体“东隆西坳”的构造格局。区内烃源岩热演化包括一次生烃和二次
生烃,并可细分为长期隆升型、后期强烈沉降深成变质型和岩浆热变质型三种类型。一次成烃主要发生在三叠系末期,二
次成烃分别在新近纪和古近纪岩浆侵入期。区内斜坡浅部和隆起区一次成烃,斜坡和凹陷深部为后期强烈沉降深成变质二
次成烃、斜坡和凸起岩浆热液侵入区发生岩浆热变质二次成烃。一次成烃期Ro 值在0.7%左右,不具成藏潜力,二次成烃
期烃源岩可达高熟、过熟阶段,成藏配置条件好,成藏潜力巨大。     

鄂尔多斯盆地西南缘奥陶系马家沟组烃源岩饱和烃特征研究

奥陶系马家沟组是鄂尔多斯盆地下古生界的烃源岩层系之一,为了进一步认识马家沟组烃源岩的地球化学特征,本文以鄂尔多斯盆地西南缘典型剖面烃源岩样品为研究对象,利用GC-MS分析方法对研究样品的饱和烃馏分进行了分析。研究表明鄂尔多斯盆地西南缘马家沟组烃源岩岩性不同,其生物标志化合物分布特征也存在差异。根据生物标志化合物特征推断,马家沟组各类源岩的沉积环境为盐度较高的还原环境,灰岩沉积环境的氧化性略高于灰质泥岩;灰岩的有机质母质来源以低等水生生物和微生物为主,而灰质泥岩有高等植物来源的有机质混入,有机质的热演化程度均达到成熟阶段;马家沟组各类源岩有机质均经历过降解作用,且碳质泥岩中有机质遭受的降解作用要强于灰岩。     

粤北大瑶山地区前泥盆纪地层中的火山岩特征及LA-ICP-MS锆石U-Pb年龄

通过1︰5万地质填图及剖面测制,作者在粤北大瑶山地区的震旦-寒武纪地层中首次发现多层火山岩,岩性主要为火山-沉积碎屑岩类的变质凝灰质不等粒岩屑石英砂岩、变质凝灰质不等粒长石石英砂岩、沉凝灰岩等,局部见变流纹质熔结凝灰岩。对变流纹质熔结凝灰岩、变质凝灰质砂岩用LA-ICP-MS法测定锆石U-Pb年龄,206Pb/238U年龄介于614~2869 Ma之间,年龄值较为分散,说明碎屑锆石是多来源的。火山岩年龄数据与地层时代归属矛盾,粤北大瑶山地区前泥盆纪地层的时代归属值得进一步探讨。     

大汶口盆地漕河崖矿段岩盐矿地质特征及岩相分布规律

通过对漕河崖矿段进行勘探工作,发现该区岩盐矿层赋存较多,矿层厚度在0．40～14．72 m,NaCl 平均品位86．39％,属厚度较稳定,品位均匀矿层;岩盐矿层不仅局限在 F2,F3,F43个断层的切割范围内,在 F3断层北部尚有岩盐层赋存。     

山东省沉积岩建造组合划分

为编制1∶50万山东省大地构造相工作底图（沉积岩区）提供依据,按照沉积岩建造组合划分原则和大地构造相研究的有关要求,划分了山东省沉积岩区大地构造相和沉积岩建造组合,将山东省沉积岩区大地构造相划分为2个相系（Ⅰ级）、3个大相（Ⅱ级）、15个相（Ⅲ级）、27个亚相（Ⅳ级）及40个建造组合（Ⅴ级）,并简要介绍了主要沉积岩建造组合基本特征。     

The late Mesozoic–Cenozoic tectonic evolution of the South China Sea: A petrologic perspective

This paper presents a review of available petrological, geochonological and geochemical data for late Mesozoic to Recent igneous rocks in the South China Sea (SCS) and adjacent regions and a discussion of their petrogeneses and tectonic implications. The integration of these data with available geophysical and other geologic information led to the following tectono-magmatic model for the evolution of the SCS region. The geochemical characteristics of late Mesozoic granitic rocks in the Pearl River Mouth Basin (PRMB), micro-blocks in the SCS, the offshore continental shelf and Dalat zone in southern Vietnam, and the Schwaner Mountains in West Kalimantan, Borneo indicate that these are mainly I-type granites plus a small amount of S-type granites in the PRMB. These granitoids were formed in a continental arc tectonic setting, consistent with the ideas proposed by Holloway (1982) and Taylor and Hayes, 1980, Taylor and Hayes, 1983, that there existed an Andean-type volcanic arc during later Mesozoic era in the SCS region. The geochonological and geochemical characteristics of the volcanics indicate an early period of bimodal volcanism (60–43 Ma or 32 Ma) at the northern margin of the SCS, followed by a period of relatively passive style volcanism during Cenozoic seafloor spreading (37 or 30–16 Ma) within the SCS, and post-spreading volcanism (tholeiitic series at 17–8 Ma, followed by alkali series from 8 Ma to present) in the entire SCS region. The geodynamic setting of the earlier volcanics was an extensional regime, which resulted from the collision between India and Eurasian plates since the earliest Cenozoic, and that of the post-spreading volcanics may be related to mantle plume magmatism in Hainan Island. In addition, the nascent Hainan plume may have played a significant role in the extension along the northern margin and seafloor spreading in the SCS.     

Geochronology and geochemistry of Cretaceous Nanshanping alkaline rocks from the Zijinshan district in Fujian Province,South China: Implications for crust–mantle interaction and lithospheric extension

In situ zircon U–Pb ages and Hf isotopic data, major and trace elements, and Sr–Nd–Pb isotopic compositions are reported for Nanshanping alkaline rocks from the Zijingshan district in southwestern Fujian Province (the Interior or Western Cathaysia Block) of South China. The Nanshanping alkaline rocks, which consist of porphyritic quartz monzonite, porphyritic syenite, and syenite, revealed a Late Cretaceous age of 100–93 Ma. All of the rocks show high SiO₂, K₂O + Na₂O, and LREE but low CaO, Fe₂O₃^T, MgO, and HFSE (Nb, Ta, P, and Ti) concentrations. These rocks also exhibit uniform initial ⁸⁷Sr/⁸⁶Sr ratios of 0.7078 to 0.7087 and ε_Nd(t) values of −4.1 to −7.2, thus falling within the compositional field of Cretaceous basalts and mafic dikes occurring in the Cathaysia Block. Additionally, these rocks display initial Pb isotopic compositions with a ²⁰⁶Pb/²⁰⁴Pb_i ratio of 18.25 to 18.45, a ²⁰⁷Pb/²⁰⁴Pb_i ratio of 15.63 to 15.67, and a ²⁰⁸Pb/²⁰⁴Pb_i ratio of 38.45 to 38.88. Combined with the zircon Hf isotopic compositions (ε_Hf(t) = −11.7 to −3.2), which are different from those of the basement rocks, we suggest that Nanshanping alkaline rocks were primarily derived from a subduction-related enriched mantle source. High Rb/Sr (0.29–0.65) and Zr/Hf (37.5–49.2) but relatively low Ba/Rb (4.4–8.1) ratios suggest that the parental magmas of these rocks were most likely formed via partial melting of a phlogopite-bearing mantle source with carbonate metasomatism. The relatively high SiO₂ (62.35–70.79 wt.%) and low Nb/Ta (10.0–15.3) ratios, positive correlation between SiO₂ and (⁸⁷Sr/⁸⁶Sr)_I, and negative correlation between SiO₂ and ε_Nd(t) of these rocks suggest that the crustal materials were also involved in formation of the Nanshanping alkaline rocks. Combined with geochemical and isotopic features, we infer magmatic processes similar to AFC (assimilation and fractional crystallization) involving early fractionation of clinopyroxene and olivine and subsequent fractionation of biotite-dominated assemblages coupled with a lesser amount of crustal contamination, thereby forming the Nanshanping alkaline rocks. The Nanshanping alkaline rocks appear to be associated with an extensional environment in the Cathaysia Block. This extensional regime could have resulted in the slab break-off and rollback of the subducting paleo-Pacific plate and the upwelling of the asthenospheric mantle, which induced partial melting of the enriched lithospheric mantle in the Cretaceous.