Uranium Series Chronology of the Late Pleistocene Basalt from the Longgang Volcanoes, Jilin Province

The Longgang volcanic cluster located in Jilin Province belongs to one of the active volcanic regions in northeast China, and has been active in modern times. In view of the multiple eruptions in history, it is very important to determine the age of each eruption for evaluating the volcanic hazards. Two alkaline basalt samples taken from Dayizishan and Diaoshuihu were analyzed with the U-series component dating after magnetic separation. The ages of the two samples are (71±9) ka and (106±13) ka B.P., respectively. These data indicate that there existed intensive eruption activities during the late Pleistocene.

Non-seismic geophysical analysis of potential geothermal resources in the Longgang Block,Northeast China

Although geothermal energy has many clear advantages,including its sustainability and environmentally friendly nature,research into potential geothermal resources across the Longgang Block,Northeast China,has been limited.Here we present the first analysis of the potential geothermal resources in this region that employs joint geological and non-seismic geophysical methods to identify target areas that may be economically viable.We acquire and analyze high-precision gravity,magnetic,and magnetotelluric sounding data,which are constrained using the petrophysical parameters of outcropping rocks across the Longgang Block,to conduct a comprehensive evaluation of the region’s deep geological structures and their geothermal resources potential,with a focus on identifying faults,rock masses,and thermal storage structures.We find that Archean granitic gneiss and Mesozoic rock masses in the deeper section of the Longgang Block possess weak gravity anomalies and high resistivities.We also identify thermal storage structures near these deeper geological units based on their extremely low resistivities.The data are used to infer the dip and depth of known or hidden faults,to constrain the spatial distribution of intrusive rock masses,and to determine the spatial distribution of subsurface thermal storage structures.The potential of the target areas for geothermal resources exploitation is divided into three grades based on contact depths between faults and thermal storage structures,and the scale of their thermal storage structures.Our results suggest that a joint non-seismic geophysical approach can be effective in locating and evaluating geothermal resources in complex geological settings.

Analysis on the Status Quo and Existing Problems of the Longgang River Basin Management

In this paper,status quo of water pollution control in the Longgang River Basin is summarized,and the current status of water environment quality is analyzed,and the main problems in water environment management are discussed.The research aims to provide reference for the management of the Longgang River basin.

The Study on Pyroclastic Deposits in the Longgang Volcanic Swarm, Northeastern China

The Dayizishan scoria cone and Jinlongdingzi scoria cone in the Longgang volcanic swarm, northeastern China are comprised of basaltic fallout tephra that derived from sub-Plinian eruptions. The airborn tephra formed a scoria cone and tephra sheets in geomorphological character. The fallout tephra deposits consist of basaltic scoria, bomb, ultramafic xenolith and lithic fragments. The tephra deposits in the tephra sheets developed plane parallel bedding and graded bedding. The size parameters of tephra changed with distance away from source and the lapse of time regularly. The Dalongwan tuff ring and Longquanlongwan tuff ring in Longgang volcanic swarm are comprised of base surge deposits, formed by phreatomagmatic explosions. The base surge deposits are composed of basaltic lapilli, pisolites and tuff. The sedimentary structure, for instance, dunelike structure, chute and pool structure, U-shaped channel and cross bedding, massive beds and sandwave beds etc. are recognized.

Numerical Simulation and Probabilistic Hazard Assessment of Tephra Fallout at Jinlongdingzi Volcano,Longgang Volcanic Field in Jilin Province

Tephra fallout is an important type of hazard caused by explosive volcanic eruption, and numerical simulation has become a fast and effective approach to assess the dispersion and deposition of tephra fallout. According to the improved 2D diffusion model of Suzuki （ 1983）, we edited a tephra diffusion program that can run in the Windows system. Based on previous data, we simulated the diffusion scope of the Jinlongdingzi volcanic eruption, which is the latest eruption in the Longgang volcanic cluster. The simulated results are in good agreement with the results from measurement in situ, indicating that the model is reliable and the parameters used in the model are suitable. By using wind profiles of ten years, 7, 021 simulations under different wind profiles were carried out, and then probabilistic hazard maps of tephra fallout were constructed for tephra thickness thresholds, lcm and 0.5cm. This study can provide an important scientific basis for volcanic hazard analysis, risk mitigation plans and countermeasures in the Longgang volcanic area.

Petrology and Geochemistry of Jinlongdingzi Active Volcano—the Most Recent Basaltic Explosive Volcano at Longgang

The Jinlongdingzi active volcano erupted before 1600a, and it is the latest basaltic explosive volcano at Longgang Volcano. Its volcanic products include the Jinlongdingzi volcanic cone (elevation 999.4m), the lava flow and the widely\|spread volcanic pyroclastic sheet (Sihai Pyroclastic Sheet). Jinlongdingzi volcanic rocks are trachybasalts with very similar REE patterns and incompatible element patterns, and their \{\{\}\+\{87\}Sr\}/\{\{\}\+\{86\}Sr\} and \{\{\}\+\{143\}Nd\}/\{\{\}\+\{144\}Nd\} ratios range from \{0.704846\} to \{0.704921\} and from \{0.512619\} to \{0.512646\}, respectively. It is revealed that the trachybasalt has the character of primary magma derived directly from mantle sources with very little evolution and crust contamination during its ascending. The younger mantle xenoliths demonstrate that the mantle source of the Jinlongdingzi Volcano is hydrous, with relatively low temperature.

Characteristics and Mechanism of Upper Permian Reef Reservoirs in the Eastern Longgang Area, Northeastern Sichuan Basin, China

As a typical kind of lithologic reservoirs,reef reservoirs are generally featured by their large single-well reservoir thickness,good reservoir physical properties,and high gas well productivity.The Upper Permian Changxing Formation is an important natural gas exploration target in the Sichuan Basin,which hosts a large reef gas reservoir and is mainly distributed along the Kaijiang-Liangping Trough.Comprehensive analyses are implemented to investigate reservoir characteristics and identify controlling factors of reef reservoirs in Changxing Formation in the Eastern Longgang Area,Northeastern Sichuan Basin,including core,logging,and seismic data analyses.Changxing Formation reservoirs in the study area mainly occur in the reef-shoal complex,which are featured by wide distribution,large thickness and generally good physical properties.Reservoir rocks are dominantly composed of bioclastic dolomite and silty-fine dolomite(with grain phantom structure),while the main reservoir space consists of residual intergranular pores,intergranular dissolution pores,and karst vugs.In the seismic profiles,typical mound-shaped chaotic reflections can be clearly seen.It is suggested by the main reservoir development controlling factor analysis that the distributions of reef reservoirs are typically controlled by sedimentary facies belts,while the scale of the reef-shoal complex is determined by the pene-sedimentary micro-paleo-geomorphology.Dolomitization can not only significantly preserve the primary pores but also enhance the permeability of rocks.Moreover,karstification is the key to high-quality reef-shoal reservoirs.

超越传统:新型设市的出现与乡镇区划建制的走向——对龙港撤镇设市的观察与思考

当前的乡镇区划建制设置具有政权组织事实上的派出化、区划分割的面状化、建制设置的差异化三大特征,这样的乡镇设置模式还存在一些问题。作为区划建制意义上的“市”制在当代中国演化出浙江龙港撤镇设市这一新型设市模式,给基层的乡镇区划建制设置模式带来了较大的冲击。未来的基层区划建制设置应超越传统的乡镇设置模式,实现从行政与自治的纠结走向两者的有机融合,从城乡分治走向城乡合治,从职责不对等走向职责对等,从多层级走向扁平化,从山川交错走向山川形便。

Metamorphic P-T conditions and zircon U-Pb ages of amphibolite in Laojinchang area,southern Jilin Province

The Longgang Block is one of the most important parts of the eastern North China Craton,characterized by extensive Late Neoarchean(~2.5 Ga)granulite facies metamorphism.However,it remains uncertain whether it was influenced by Paleoproterozoic magmatism-metamorphism.The authors provide a comprehensive analysis of amphibolite in Laojinchang area,southern Jilin Province,through petrographic,geochemical,mineralogical,and zircon dating.The main findings are as follows:The mineral assemblage of amphibolite is Hb+Pl+Cpx+Bi+Kf+Q,characteristic of amphibolite facies;zircon U-Pb dating indicates that the metamorphic age of amphibolite is 1834±33 Ma;the amphibolite has geochemical characteristics of calcium alkaline,with depletion of Nb,Ta,Ti and P.The plagioclase in the amphibolite is oligoclase,belonging to acidic plagioclase.It is speculated that the protolith of the amphibolite is diorite;using geothermobarometer,the peak metamorphic P-T conditions of amphibolite are determined to be 536–593℃/3.4–5.0 kbar,and the post-peak conditions are 429–566℃/1.3–3.1 kbar.The above results indicate that the Paleoproterozoic metamorphism has been superimposed on Longgang Block,linked to a new orogenic event on the northern edge of North China Craton.

整体智治理念下县域综合行政执法改革的逻辑基础与规制路径——基于对龙港市“一支队伍管执法”的观察

在全国综合行政执法改革实践中,“一支队伍管执法”主要集中在乡镇(街道)层级,县域“一支队伍管执法”是龙港市推进新型城镇化综合改革探索的创新实践。龙港市综合行政执法改革遵循“不建机构建机制,不增层级增协同”的原则,遵循条块协同、整体智治理念,将专业化、数字化、科学化嵌入改革全过程,使法治、协同、效能、服务为民等价值属性统一于县域行政执法领域,形成独具特色的“市直管社区”综合行政执法地方实践。整体智治作为政府数字化转型背景下基层治理模式的创新实践,其核心逻辑表现为将制度和技术嵌入治理过程,重置治理结构、重整治理资源、提升治理质效。构建综合行政执法整体智治的治理机制,通过“执法队伍—执法手段—执法程序—执法监督”全过程闭环、多维度规制路径,能够有效破解当前县域“一支队伍管执法”在执法理念、体系构建、体制重整、规范配套及队伍能力尚存短板的难题,保障县域综合行政执法改革成效。

三维大地电磁方法揭示的吉林龙岗板内单成因火山深部岩浆系统

板内火山作用是指在远离板块构造边界的大陆内部发生的火山活动,位于中国东北的龙岗火山是研究板内火山活动的天然实验区. 我们分别于2020年和2022年在吉林龙岗火山区及其周围区域连续开展大地电磁测量工作,获得了覆盖龙岗火山区的141个宽频带测点数据,通过三维反演获得了该区域地壳上地幔尺度精细的三维电性结构模型. 该模型揭示出龙岗火山区及其周边地区上地壳基本上为高阻体,代表着火山区岩浆早期活动时大面积喷发冷凝所产生的火山岩. 龙岗火山区下方存在着多条岩浆通道穿过莫霍面在上地幔尺度合并且向下继续延伸. 这些岩浆通道自下而上可能主导了近期火山喷发和地壳隆升以及小震活动. 该模型清晰的显示了一个大陆板内火山系统从地幔源到地表跨岩石圈的形成机制,结合岩石学和地球化学资料,推测龙岗火山区的岩浆系统可能直接从软流圈地幔快速上升至地壳内部减压熔融导致喷发作用. 这些结果不但可以为龙岗火山区喷发风险的预测提供深层地球物理依据,也能为理解板内火山形成机制提供启发.

以人为本理念下县域城镇化的龙港实践:历史基因与当代改革

以人为本是我国当代城镇化建设的核心理念,而县域是践行这一理念的重要载体。实际上,人本城镇化在县域层面的实践早已展开,而浙江龙港就是其中的典型代表。作为中国第一农民城、新型城镇化改革第一批综合试点,以及新世纪以来撤镇设市区划调整的仅有案例,龙港在40年的城镇发展历程中,涌现了从自发到自觉的两轮人本城镇化实践,即城镇建设初期的“共同城镇化”和新型城镇化改革时期的“全域市民化”。在历史基因与当代改革中,以人为本理念下县域城镇化的龙港实践背后蕴含着“政府—社会—市场”关系的“变与不变”:变化体现在三者角色调整下的整体结构演进,不变的则是三者之间良性互动等微观机制。

深圳龙岗区2023年“9·7”极端特大暴雨洪涝灾害风险评估与对策

2023年9月7—8日,深圳市出现超历史纪录的极端特大暴雨,打破了深圳市1952年有气象记录以来7项历史极值,其中龙岗区暴雨中心爱联河片区3 h降雨量超100年一遇,导致城市内涝积水。以深圳龙岗区爱联河片区为例,构建城市暴雨洪涝耦合模型,对2023年“9·7”极端特大暴雨洪涝情况进行模拟,分析龙岗中心城区内涝积水情况,为揭示洪涝灾害成因和提出防治对策提供依据。

高度城市化地区区级生态修复规划路径探索——以深圳市龙岗区为例

国土空间生态修复已成为当前自然资源领域落实“绿水青山就是金山银山”理念的重要抓手,也是新时期生态文明建设的重大战略任务。文章通过剖析国土空间生态修复的概念内涵、相关城市的实践经验以及现行区级生态修复规划在全域统筹、规划传导与实施机制上的不足,提出新时期背景下的区级国土空间生态修复规划策略。以深圳市龙岗区为例,从自然资源全要素分析、生态安全格局构建、生态修复管控体系、生态修复联动机制等方面提出生态修复策略,探索面向区级的国土空间生态修复规划方法,以期对相关规划实践提供参考。

龙岗河流域2023年“9·7”极端特大暴雨洪涝反演分析

深圳“9·7”极端特大暴雨导致龙岗流域发生严重洪涝灾害,由于该流域缺乏水文监测站,给洪涝分析和灾害复盘带来挑战。为明晰小尺度城市流域洪涝灾害特点,本研究结合现场调查和实测水位数据,采用实测降雨资料,修正暴雨等值线图参数,推求流域各典型断面设计洪水,通过洪涝数学模型模拟演算,分析暴雨洪涝计算成果,并与流域设计洪水比较,给出2023年“9·7”龙岗河洪水等级。进一步剖析暴雨洪涝特性及成因,并围绕洪涝灾害防治中存在问题,提出从工程措施和非工程措施两个方面完善防洪体系对策建议,以期为高密度城市小尺度流域洪涝灾害防治工作提供参考。

微型桩与预应力锚索格构梁在滑坡工程中的应用

滑坡工程常遇到施工场地受限、作业空间狭窄、大型施工机械无法到达等特殊情况,需要根据工程环境选择最优治理方案。微型桩组合抗滑结构具有施工方便、保证施工人员安全、经济性高、对坡体扰动小等优点,可用于滑坡地质灾害治理工程中。本文以广东深圳龙岗区某滑坡为例,阐述微型桩与预应力锚索格构梁边坡支护方案主要施工过程及实施技术,达到滑坡治理的目标。

吉林龙岗第四纪火山活动分期

在约 170 0 km2的龙岗火山区内分布 10 0多个玄武质岩浆爆破成因的火山渣锥和射气岩浆成因的低平火山口 -龙湾 ,最新喷发距今约 150 0～ 160 0年。本文在火山地质研究基础上 ,测定了龙岗第四纪火山活动形成的熔岩台地、火山渣锥、低平火山口、火山碎屑席等不同火山地质体的 3 1个火山岩 K-Ar年龄和 2个炭化木与泥炭层的 14C年龄 ,厘定了龙岗第四纪 3期火山活动的时间 :小椅山期 (早更新世 :2 .15～ 0 .75Ma)、龙岗期 (中 -晚更新世 :0 .68～ 0 .0 5Ma)和金龙顶子期 (全新世 :160 0～ 150 0 a.BP)

龙岗火山群第四纪爆破式火山作用类型与期次研究

龙岗火山群位于吉林省辉南和靖宇县境内的龙岗山脉中段。火山活动始于新近纪,第四纪更新世为鼎盛期,全新世以来仍有较强的喷发活动,是中国近代活动火山区之一。火山碎屑物的堆积构造、组成、显微形貌和粒度特征表明,第四纪爆破式火山作用包括岩浆爆发、射汽．岩浆爆发和射汽爆发三种类型,以岩浆和射汽-岩浆爆发最为发育。区内爆破式火山活动具有多旋回、多期次、多阶段喷发特点。据火山地质特征,可划分为9期,由老至新为:早更新世早期、晚期;中更新世三角龙湾期、旱龙湾期和金龙顶子早期;晚更新世金川东期;全新世大翁圈期、红期林场期和金龙顶子晚期。爆破式火山灾害的范围较大,岩浆爆发中高危区的半径约10km。射汽-岩浆爆发影响的半径约4km。

四川盆地超深层天然气地球化学特征

对四川盆地38口井超深层(埋深大于6 000 m)天然气组分及其地球化学特征进行分析,以判明超深层天然气成因。四川盆地超深层天然气组分具如下特征:甲烷占绝对优势,含量最高达99.56%,平均86.67%;乙烷含量低,平均为0.13%;几乎没有丙、丁烷,为干气,属过成熟度气。硫化氢含量最高为25.21%,平均为5.45%;烷烃气碳同位素组成为:δ^(13)C_1值从-33.6‰变化至-26.7‰,δ^(13)C_2值从-32.9‰变化至-22.1‰,绝大部分没有倒转而主要为正碳同位素组成系列。烷烃气氢同位素组成为:δD_1值从-156‰变化至-113‰,少量井δD_2值从-103‰变化至-89‰。二氧化碳碳同位素组成为:δ^(13)C_(CO_2)值从-17.2‰变化至1.9‰,绝大部分在0±3‰范围。根据δ^(13)C_1-δ^(13)C_2-δ^(13)C_3鉴别图版,盆地超深层烷烃气除个别井外绝大部分为煤成气。根据二氧化碳成因鉴别图和δ^(13)C_(CO_2)值,判定除个别井外,超深层二氧化碳绝大部分为碳酸盐岩变质成因。龙岗气田和元坝气田超深层硫化氢为非生物还原型(热化学硫酸盐还原成因),双探号井的超深层硫化氢可能为裂解型(硫酸盐热裂解成因)。

龙岗金垅顶子近代活动火山的岩石学与地球化学

距今１６００ 年前喷发的金龙顶子火山是龙岗火山群中一座最年轻的近代活动火山， 它的喷发物包括金龙顶子火山锥体 （海拔９９９．４ｍ ）、熔岩流及其广布的火山碎屑席 （四海火山渣层）。金龙顶子火山岩为单一的粗面玄武岩， 有着极为相似的ＲＥＥ和不相容元素分布模式， ８７Ｓｒ／８６Ｓｒ和１４３Ｎｄ／１４４Ｎｄ 分别变化于０．７０４８４６～０．７０４９２１ 和０．５１２６１９～０．０．５１２６４６， 这反映了它们直接来自地幔源区， 岩浆上升过程极少演化和壳源混染， 具有较为原始的岩浆特点。年轻火山岩中的幔源捕虏体提供了该区存在相对低温 （～９００℃） 含水的地幔。