松辽盆地北部上二叠统林西组地球化学特征及地质意义     

张健  张海华  陈树旺  郑月娟  张德军  苏飞  黄欣 《吉林大学学报(地球科学版)》2020,50(2):518-530

为探讨松辽盆地北部林西组地球化学特征、沉积环境及构造背景，对该区黑富地1井所钻遇的上二叠统林西组暗色泥质板岩进行主量元素、微量元素和稀土元素测试分析，结果表明：样品主量元素平均质量分数SiO₂为65.05%、Al₂O₃为17.23%、CaO为2.58%、Na₂O为2.84%、K₂O为3.29%，K₂O/Na₂O值为0.20~3.48，A1₂O₃/（CaO+Na₂O）值为0.41~8.01；稀土元素w（∑REE）值介于80.68×10^-6~215.59×10^-6之间，平均值为173.41×10^-6，δEu值介于0.61~0.88之间，平均值为0.70，表现为Eu的负异常，δCe值介于0.91×10^-6~1.01×10^-6之间，为微弱的Ce负异常，LREE富集，HREE亏损；微量元素以亏损Nb、Ta、Sr，相对富集Rb、Ba、La、Ce、Pb、Nd、Sm为特征。样品元素分析和物源w（TiO₂）-w（Ni）、La/Th-w（Hf）等判别图解表明，林西组沉积物源具有多样性，主要来源于上地壳长英质物源，还有少量来自中、基性岩火成岩物源区。样品微量元素标准化蛛网图，稀土元素球粒陨石标准化配分模式图，K₂O/Na₂O-w（SiO₂）、Th-Co-Zr/10、F₂-F₁构造背景判别图及地球化学参数对比结果表明，松辽盆地北部林西组物源构造背景主要为活动大陆边缘和大陆岛弧，可能形成于靠近大陆岛弧的活动大陆边缘构造背景。林西组应形成于海陆过渡相到陆相环境，水体由半咸水逐渐转变为淡水。  相似文献   

渤海湾盆地歧口凹陷地层压力结构特征     

姜文亚  宋泽章  周立宏  蒲秀刚  王娜  代昆  万伟超  刘祥柏 《吉林大学学报(地球科学版)》2020,50(1):52-69

深化含油气沉积盆地的压力结构研究，厘清异常压力的空间展布，对划分含油气系统、评价有利输导体系与明确勘探甜点区带具有重要的理论和实践意义。为深化渤海湾盆地富油凹陷的油气二次勘探，本文以歧口凹陷为研究对象，对其压力结构进行重点刻画。在实测地层压力的校正下，综合单井、连井和二维地震地层压力结构分析，厘清了歧口凹陷的压力结构特征，识别出4类纵向压力结构：①单超压带结构；②双超压带结构；③多超压带结构；④静水压力结构。纵向上，歧口地区存在3类纵向压力系统样式——单超压系统、双超压系统、静水常压系统。双超压系统是歧口凹陷的主要压力系统样式，广泛发育于主凹和各大次凹；从凹陷中心向盆地边缘，双超压系统逐渐向单超压系统、静水常压系统过渡。单超压系统主要分布于盆地边缘的斜坡和潜山区，如歧北高斜坡、羊三木-扣村潜山等。静水常压系统则主要分布在离深凹区更远的沈青庄潜山和埕北斜坡区域。上部超压系统和下部超压系统的顶板分别位于东营组和沙三段内部，侧向上受盆地边缘和深大断裂控制。上部超压系统的形成主要受欠压实作用控制，以歧口主凹为中心呈环带分布；而下部超压系统的形成主要受生烃作用控制，以主凹和几大次凹为中心分布。未来，下部超压系统中保存的天然气将成为歧口地区超深层天然气勘探的重点对象。  相似文献   

四川盆地广安地区中二叠统栖霞组岩石特征与沉积环境     

易海永  崔宝琛  王瑶琳  邱玉超  徐胜林  李乾 《吉林大学学报(地球科学版)》2020,50(2):454-464

四川盆地中二叠统栖霞组勘探发现系列油气，资源潜力巨大。但广安地区中二叠统栖霞组的岩石学特征及沉积环境研究薄弱。在野外地质调查的基础上，结合室内岩石学、岩相学等综合分析，对广安地区栖霞组碳酸盐岩岩石特征、沉积相类型及其古地理展布特征进行了系统研究。结果表明：广安地区栖霞组主要发育亮晶颗粒灰岩、亮晶生物碎屑灰岩、微晶生物碎屑灰岩、微晶颗粒灰岩、生物碎屑微晶灰岩、含生物碎屑微晶灰岩和泥晶灰岩7种岩石类型；碳酸盐岩颗粒主要以生物碎屑为主，部分层位发育球粒；古生物化石以三叶虫、腕足和有孔虫为主，同时可见棘皮类和藻类；栖霞组沉积期主要为碳酸盐岩台地沉积环境，其中栖霞组晚期（栖二段）台缘滩和台内滩较为发育，为该区油气成藏提供了有利条件。  相似文献   

尺度政治视角下的新安江流域生态补偿政府主体博弈     

任以胜  陆林  虞虎  朱道才 《地理学报》2020,75(8):1667-1679

流域生态补偿是中国跨区域生态治理和自然区域保护的一项重要经济、社会、环境政策,涉及区域利益主体权益差异与协调、区域生态协同发展和合作模式构建等方面,是一个典型的地理学研究命题。本文将制度粘性引入到尺度政治理论中,剖析新安江流域生态补偿政府主体的博弈行为,探究不同政府主体的博弈特征和博弈机制。结果表明:中央政府、省级政府、市级政府等不同层级政府主体经历了竞争博弈、合作博弈和竞合博弈3个阶段,构建政府利益共同体能够推进流域生态补偿建设,中央政府的“适度介入”是开展跨省流域生态补偿的关键;流域生态补偿制度从“垂直”模式向“垂直—水平”模式的变迁过程中存在明显的制度粘性,政府主体利用政策革新和社会参与等制度约束稀释制度粘性,重塑流域生态补偿制度;尺度转换是推动新安江流域生态补偿的核心机制,政府主体通过重新分配权力和资本、嵌入非正式约束塑造流域生态补偿话语体系,推动新安江流域生态补偿由“强国家—弱社会”向“强国家—强社会”结构模式的转变。研究结果能够为构建跨区域流域生态补偿机制提供理论支撑,为合理评价和指导流域生态补偿实践、促进流域经济社会协调可持续发展提供科学依据。  相似文献   

Recognition of two contrasting structural-and mineralogical-gold mineral systems in the Youjiang basin,China-Vietnam:Orogenic gold in the south and Carlin-type in the north     

《地学前缘(英文版)》2020,11(5):1477-1494

The gold deposits in the Youjiang basin,totaling 25 Moz gold,have traditionally been thought to be of Carlintype,particularly those with extensional structural geometries in the northern basin dominated by platform sedimentary sequences.However,the structural geometries,mineralization styles and alteration types for the Jinya,Gaolong and Nakuang gold deposits in the south-central part of the basin are remarkably similar to those of unequivocal orogenic gold deposits.Structural studies show that gold mineralization in the three gold deposits was controlled by tight "locked-up"anticlines with NW—SE-to E-W-trending and/or concomitant thrusts and/or shear zones,which resulted from NE-SW-to N-S-trending compression or transpression following the Early Triassic closure of the Paleo-Tethyan Ocean.Alteration zones in these deposits are dominated by silicification(quartz),sericitization,sulfidation and carbonation.Zoned pyrites in these deposits comprise Au-poor cores and invisible Au-bearing rims with minor external free gold.Euhedral to subhedral auriferous arsenopyrites also contribute to the gold budget.These features indicate that the three gold deposits are sediment-hosted orogenic gold deposits that contrast markedly with the Carlin-type gold deposits in the northern part of the Youjiang basin in terms of structural geometry and timing,mineralization style and nature of associated alteration.Although additional reliable ages using robust methodologies are still required,the older isotopic ages of the gold deposits in the south-central Youjiang basin are also consistent with earlier formation during transpression that predated extension during orogenic collapse,the period of formation of the Carlin-type gold deposits in the northern Youjiang basin.  相似文献   

广西合浦盆地干热岩资源成热条件及潜力评价     

康志强  张起钻  管彦武  冯波  袁金福  孙明行  刘德民  王新宇  杨志强  陆济璞  张勤军  冯民豪 《吉林大学学报(地球科学版)》2020,50(4):1151-1160

为了对广西合浦盆地干热岩资源成热条件及其潜力进行评价，利用广西航磁勘查数据，采用Parker-Oldenburg法反演计算了居里面深度。在此基础上进行大地热流密度值和不同埋深地温计算，发现计算结果与现有测温资料吻合，合浦盆地内西场凹陷和常乐凹陷具有干热岩资源成生条件。结合合浦盆地内基础地质调查资料和油气钻孔资料，分析了合浦盆地干热岩资源的储层和盖层条件。初步圈出2个位于西场凹陷和常乐凹陷的干热岩勘查靶区C1和C2，面积分别为167.10和72.90 km²，干热岩资源量分别为182.48×10¹⁵、77.59×10¹⁵ J。按20%的采收率，合浦盆地干热岩资源量可开采量为52.01×10¹⁵ J，折合标准煤177.48×10⁴ t，占2018年广西全区能源生产总量3 756.69×10⁴ t标准煤的4.72%。在资源量评价基础上，可优先考虑位于合浦盆地西场凹陷的C1靶区开展进一步的勘探工作。  相似文献   

Ophiolite hosted chromitite formed by supra-subduction zone peridotite –plume interaction     

《地学前缘(英文版)》2020,11(6):2083-2102

Chromitite bodies hosted in peridotites typical of suboceanic mantle (s.l. ophiolitic) are found in the northern and central part of the Loma Caribe peridotite, in the Cordillera Central of the Dominican Republic. These chromitites are massive pods of small size (less than a few meters across) and veins that intrude both dunite and harzburgite. Compositionally, they are high-Cr chromitites [Cr# ​= ​Cr/(Cr ​+ ​Al) atomic ratio ​= ​0.71–0.83] singularly enriched in TiO₂ (up to 1.25 ​wt.%), Fe₂O₃ (2.77–9.16 ​wt.%) as well as some trace elements (Ga, V, Co, Mn, and Zn) and PGE (up to 4548 ​ppb in whole-rock). This geochemical signature is unknown for chromitites hosted in oceanic upper mantle but akin to those chromites crystallized from mantle plume derived melts. Noteworthy, the melt estimated to be in equilibrium with such chromite from the Loma Caribe chromitites is similar to basalts derived from different source regions of a heterogeneous Caribbean mantle plume. This mantle plume is responsible for the formation of the Caribbean Large Igneous Province (CLIP). Dolerite dykes with back-arc basin basalt (BABB) and enriched mid-ocean ridge basalt (E-MORB) affinities commonly intrude the Loma Caribe peridotite, and are interpreted as evidence of the impact that the Caribbean plume had in the off-axis magmatism of the back-arc basin, developed after the Caribbean island-arc extension in the Late Cretaceous. We propose a model in which chromitites were formed in the shallow portion of the back-arc mantle as a result of the metasomatic reaction between the supra-subduction zone (SSZ) peridotites and upwelling plume-related melts.  相似文献   

Timing and development of sedimentation of the Cleaverville Formation and a post‐accretion pull‐apart system in the Cleaverville area,coastal Pilbara Terrane,Pilbara, Western Australia     

Shoichi Kiyokawa  Yuhei Aihara  Mami Takehara  Kenji Horie 《Island Arc》2019,28(6)

In the Cleaverville area of Western Australia, the Regal, Dixon Island, and Cleaverville Formations preserve a Mesoarchean lower‐greenschist‐facies volcano‐sedimentary succession in the coastal Pilbara Terrane. These formations are distributed in a rhomboidal‐shaped area and are unconformably overlain by two narrowly distributed shallow‐marine sedimentary sequences: the Sixty‐Six Hill and Forty‐Four Hill Members of the Lizard Hills Formation. The former member is preserved within the core of the Cleaverville Syncline and the latter formed along the northeast‐trending Eighty‐Seven Fault. Based on the metamorphic grade and structures, two deformation events are recognized: D₁ resulted in folding caused by a collisional event, and D₂ resulted in regional sinistral strike‐slip deformation. A previous study reported that the Cleaverville Formation was deposited at 3020 Ma, after the Prinsep Orogeny (3070–3050 Ma). Our SHRIMP U–Pb zircon ages show that: (i) graded volcaniclastic–felsic tuff within the black shale sequence below the banded iron formation in the Cleaverville Formation yields an age of (3 114 ±14) Ma; (ii) the youngest zircons in sandstones of the Sixty‐Six Hill Member, which unconformably overlies pillow basalt of the Regal Formation, yield ages of 3090–3060 Ma; and (iii) zircons in sandstones of the Forty‐Four Hill Member show two age peaks at 3270 Ma and 3020 Ma. In this way, the Cleaverville Formation was deposited at 3114–3060 Ma and was deformed at 3070–3050 Ma (D₁). Depositional age of the Cleaverville Formation is at least 40–90 Myr older than that proposed in previous studies and pre‐dates the Prinsep Orogeny (3070–3050 Ma). After 3020 Ma, D₂ resulted in the formation of a regional strike‐slip pull‐apart basin in the Cleaverville area. The lower‐greenschist‐facies volcano‐sedimentary rocks are distributed only within this basin structure. This strike‐slip deformation was synchronous with crustal‐scale sinistral shear deformation (3000–2930 Ma) in the Pilbara region.  相似文献   

The timing of salt structure growth in the Southern Permian Basin (Central Europe) and implications for basin dynamics     

Michael Warsitzka  Fabian Jhne‐Klingberg  Jonas Kley  Nina Kukowski 《Basin Research》2019,31(2):337-360

In this paper, a literature‐based compilation of the timing and history of salt tectonics in the Southern Permian Basin (Central Europe) is presented. The tectono‐stratigraphic evolution of the Southern Permian Basin is influenced by salt movement and the structural development of various types of salt structures. The compilation presented here was used to characterize the following syndepositional growth stages of the salt structures: (a) “phase of initiation”; (b) phase of fastest growth (“main activity”); and (c) phase of burial’. We have also mapped the spatial pattern of potential mechanisms that triggered the initiation of salt structures over the area studied and summarized them for distinct regions (sub‐basins, platforms, etc.). The data base compiled and the set of maps produced from it provide a detailed overview of the spatial and temporal distribution of salt tectonic activity enabling the correlation of tectonic phases between specific regions of the entire Southern Permian Basin. Accordingly, salt movements were initiated in deeply subsided graben structures and fault zones during the Early and Middle Triassic. In these areas, salt structures reached their phase of main activity already during the Late Triassic or the Jurassic and were mostly buried during the Early Cretaceous. Salt structures in less subsided sub‐basins and platform regions of the Southern Permian Basin mostly started to grow during the Late Triassic. The subsequent phase of main activity of these salt structures took place from the Late Cretaceous to the Cenozoic. The analysis of the trigger mechanisms revealed that most salt structures were initiated by large‐offset normal faults in the sub‐salt basement in the large graben structures and minor normal faulting associated with thin‐skinned extension in the less subsided basin parts.  相似文献   

2016年夏季南海海盆水体颗粒物粒径分布特征*     

郑文迪  周雯  曹文熙  王桂芬  邓霖  徐文龙  许占堂  李彩  蔡建南 《热带海洋学报》2018,37(5):74-85

颗粒物粒径分布(Particle Size Distribution, PSD)代表了颗粒物浓度与颗粒物粒径之间的关系, 影响着海洋生态环境和水体光学特性等。文章基于2016年夏季航次调查的生物光学剖面数据, 研究了南海海盆海域PSD的分布特征。研究发现, 幂律函数可以较好地拟合南海海盆区域的PSD, 对数空间中的实测的PSD与模拟的PSD平均决定系数高达0.95。PSD斜率(ξ)的分布范围为[1.27, 7.65], 均值为3.93±0.56。南海海盆区域表层水体的ξ均值与全球大洋表层水体的ξ均值相近, 但高于海湾等表层水体的ξ均值。ξ能较好地表征颗粒物平均粒径D_A的大小, 两者存在明显负相关关系, 即ξ值越高, D_A越小; 反之, D_A越大。通过分析T1断面的生物光学剖面数据及总体平均的PSD剖面数据, 发现PSD剖面分布特征如下: 1)表层水体的ξ值相对较高, 且D_A值相对较低, 推测可能是由于微微型藻类为主导颗粒物所致; 2) ξ值极小值层出现在次表层叶绿素浓度极大值层(Subsurface Chlorophyll Maximum Layer, SCML)中, 并伴随D_A极大值层的出现, 其原因可能是SCML中的大粒径浮游植物占比显著增加; 3)弱光层中的ξ值较SCML中的高, 但略低于表层的ξ值, 而D_A则位于表层与SCML的D_A之间, 这可能与浮游植物及其碎屑的絮凝、分解、沉降等过程相关。PSD特征影响着海水的固有光学特性, 分析发现: 由于SCML中的叶绿素浓度增加, 颗粒物散射系数(b_p(532))和颗粒物后向散射系数(b_bp(532))也相应呈现显著增加的趋势。弱光层中的平均b_p(532)与平均b_bp(532)最小。ξ与颗粒物衰减光谱斜率之间呈高分散性, Boss 等(2001b)的模型适合用于粗略估算区域性的ξ分布范围及均值。  相似文献