A Cretaceous Desert-Playa Sedimentary System Controlled the Potash Formation in the Simao Basin

Objective The Simao Basin in Yunnan Province has developed Cretaceous evaporite-bearing clastic deposits, including the Mangang and Mengyejing Formations which were originally interpreted as fluvial and lacustrine deposits. The Mangang Fm. composed of well-rounded quartz sandstones, were commonly considered as the bottom part of the Mengyejing salt series. Dttring last decades,

Crustal thicknesses and Poisson's ratios beneath the Chuxiong-Simao Basin in the Southeast Margin of the Tibetan Plateau

In the Southeast Margin of the Tibetan Plateau, low-velocity sedimentary layers that would significantly affect the accuracy of the H-κ stacking of receiver functions are widely distributed.In this study, we use teleseismic waveform data of 475 events from 97 temporary broadband seismometers deployed by ChinArray Phase I to obtain crustal thicknesses and Poisson's ratios within the Chuxiong-Simao Basin and adjacent area, employing an improved method in which the receiver functions are processed through a resonance-removal filter, and the H-κ stacking is time-corrected.Results show that the crustal thickness ranges from 30 to 55 km in the study area, reaching its thickest value in the northwest and thinning toward southwest, southeast and northeast.The apparent variation of crustal thickness around the Red River Fault supports the view of southeastern escape of the Tibetan Plateau.Relatively thin crustal thickness in the zone between Chuxiong City and the Red River Fault indicates possible uplift of mantle in this area.The positive correlation between crustal thickness and Poisson's ratio is likely to be related to lower crust thickening.Comparison of results obtained from different methods shows that the improved method used in our study can effectively remove the reverberation effect of sedimentary layers.

On Geodynamic Evolution of Simao Region (Southwestern Yunnan, China) during Late Paleozoic and Triassic

Over the last years, the Simao region, southwestern Yunnan, China, turned out to be a very promising target to elucidate plate tectonic processes around the Permian Triassic boundary within the Tethyan domain of Asia. New data from this area reveal that Upper Paleozoic compressional deformations occurred along the Lancangjiang and in areas to the east. Along Lancangjiang, an angular unconformity is exposed, which separates quartz phyllites—formed during a Carboniferous tectono metamorphic event—from Triassic red beds to roofing rhyolites. The acidic volcanics were often said to be remnants of a volcanic arc that was active during the Triassic subduction and closure of an oceanic realm along the Lancangjiang zone. According to our new data, however, these volcanics indicate most probably an Upper Triassic stage of rifting. In the Yunxian anticline (NW of Simao), an angular unconformity of intra Permian age is exposed where Carboniferous to lower Middle Permian strata, which were deposited in a rather deep basin, are unconformably overlain by a shallow marine sequence of upper Middle to Upper Permian sediments. The angular unconformity is of the same age as the syn orogenous sediments first described and dated from the Phetchabun region in Thailand and hence a convincing argument for a Late Variscan orogeny forming an extensive zone of mountain building that can be traced through the central parts of mainland Southeast Asia.

Provenance and Paleogeography of the Late Cretaceous Mengyejing Formation,Simao Basin,Southeastern Tibetan Plateau

The Mengyejing potash salt deposit(MPSD)is the only pre-Quaternary potash salt deposit in China.The MPSD is located in the southern Simao Basin,southeastern Tibetan Plateau.The MPSD,along with rock salts and clastic rocks,

New Sr Isotope Evidence to Support the Material Source of the Mengyejing Potash Deposit in the Simao Basin from Ancient Marine Halite or Residual Sea

Objective The Mengyejing potash deposit in the Simao Basin is the only producing area of solid potash at present in China. There is still controversy about the material source and distribution of the potash in this deposit （Shen Lijian et al., 2017）, which has influenced not only the prospecting direction and efficiency but also the understanding of the control of Tethys tectonic evolution on the formation and distribution of the mineral resources. This work analyzed the Sr isotope geochemical characteristics of evaporites from core samples in the well MZK-3 in order to further clarify the material source and to explore the potash distribution in the Simao Basin.

Geochemical Constraints on the Origin and Evolution of Spring Waters in the Changdu-Lanping-Simao Basin, Southwestern China

Chemical and isotopic data were measured for 51 leached brine springs in the Changdu-Lanping-Simao Basin(CD-LP-SM),China.The predominance of Cl and Na,saturation indices of carbonate minerals,and Na/Cl and Ca/SO4 ratios of^1 suggest that halite,sulphate,and carbonate are the solute sources.Integration of geochemical,δ18 O,andδD values suggests that springs are mainly derived from meteoric water,ice-snow melt,and water-rock interactions.B concentrations range from 0.18 to 11.9 mg/L,withδ11 B values of-4.37‰to+32.39‰,indicating a terrestrial source.Theδ11 B-B relationships suggest B sources of crustal origin(marine carbonates with minor crust-derived volcanics);we did not identify a marine or deep mantle origin.Theδ11 B values of saline springs(+4.61‰to+32.39‰)exceed those of hot(-4.37‰to+4.53‰)and cold(-3.47‰to+14.84‰)springs;this has contributed to strong water-rock interactions and strong saturation of dissolved carbonates.Conversely,the global geothermalδ11 B-Cl/B relationship suggests mixing of marine and non-marine sources.Theδ11 B-Cl/B relationships of the CD-LP-SM are similar to those of the Tibet geothermal belt and the Nangqen Basin,indicating the same B origin.These differ from thermal waters controlled by magmatic fluids and seawater,suggesting that B in CD-LP-SM springs has a crustal origin.

Fault Zone Fluid Deep-penetrating Techniques for Potash Deposit Prediction in Lanping-Simao Basin,Yunnan,South China

In China,the strategic resource potash is suffering from severe shortages,and the ancient marine solid potash locating is still a problem of long impregnability.Till now,only the Mengyejing Potash Deposit was found

The Electrical Conductivity Structure of the Lanping–Simao Basin and its Implications for Mineralization

Objective The Lanping-Simao Basin in western Yunnan, located in the southeastern margin of the Tibetan Plateau, is tectonically in the transition zone between the Gondwana and Eurasia tectonic domains. It is also the frontier zone of northeastern extrusion of the Indochina Plate towards the Eurasia Plate as well as the escape zone for the deep material. The middle axial tectonic zone, also known as the Lanping-Simao Fault （LSF） in previous study, is a giant intraplate tectonic belt composed of a series of narrow uplift belt, rupture depression zone, metamorphic belt, alteration belt and marginal fracture system, which were formed by the compressional uplift of the central depression of the Lanping-Simao Basin. This tectonic unit controls the geological evolution, seismic activity, hot spring distribution and ore formation of the LanpingSimao Basin since the Mesozoic and Cenozoic.

Clay Mineralogical and Geochemical Studies of Detrital Rocks of the Upper Cretaceous Salt-bearing Strata,Simao Basin,SW China:Implication for Provenance and Source Weathering

1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and

TECTONIC SETTING OF ORGANIC MINERALIZATION IN THE LANPING-SIMAO BASIN,WESTERN YUNNAN, SW CHINA

The Tertiary is the main mineralization period in the Lanping-Simao Basin.The deposits are rich in organic matter and the organie matter takes part in the metal and nonmetal mineralization process. The organic mineralization is controlled by the tectonic setting.Different tectonic setting results in different mineralization and type of organic matters.

思茅区国有林场森林可持续经营试点模式及技术措施探讨

通过对普洱市思茅区国有林场资源状况分析,重点剖析森林经营制约的因素,并针对制约因素提出思茅区国有林场森林经营试点模式及技术措施,对普洱市森林经营提供可借鉴的经营模式和技术措施,具有示范推广作用。

New insights on the age of the Mengyejing Formation in the Simao Basin,SE Tethyan domain and its geological implications

Knowledge on the origin and mechanism of the large potash formation in the southeast Tethyan tectonic domain are still under debate,one of which mainly due to the controversial ages of the potash-bearing strata.Here we present a detailed detrital zircon U-Pb geochronologic-magnetostratigraphic study of the potash-bearing Mengyejing(MYJ)Formation(Fm)from the Simao Basin.948 paleomagnetic cores and 4 detrital zircon U-Pb samples were collected from a 932-m thick Jiangcheng section.Thermal demagnetization isolated 857 primary characteristic remnant magnetization(ChRM)directions,indicated by positive reversals and fold tests and petrologic examinations.Seven normal and seven reversed polarity zones were identified and correlated well with chrons C27r to C34n of the geomagnetic polarity timescale(GPTS2012),yielding the first known age sequence of>112 to~63 Ma for the MYJ Fm.The ages for the potash bearing strata in the Simao commenced~20 Ma earlier than those in the adjacent Khorat basins,opposite to the traditional viewpoint that the former would rather correspond to the middle and lower parts of the latter.Given the paleogeographic reconstruction of likely a pan-Simao-Khorat basin during the Cretaceous,~85 Ma would be another important potential period for future potash exploration in the Simao Basin.

思茅关贸易研究

思茅关于1897年为法国强迫清政府设立,并侵夺其人事行政权,无端欺压商民,对云南经济造成了严重损害。本关主要进出口棉花、茶叶等商品,后因交通、政局等多重因素影响不得不关闭。思茅关的历史也是近代海关历程的真实写照。

思茅盆地页岩气地质条件及资源潜力分析

根据野外调查及样品测试,从富有机质页岩的地化特征、物性特征及保存条件等分析了思茅盆地页岩气地质条件。研究表明:思茅盆地发育下密地组、羊八寨组、挖鲁八组及和平乡组四套暗色页岩;其中,羊八寨组页岩累计厚度普遍大于100 m,TOC平均为1.06%~2.54%,R o平均为1.81%~3.47%,有机质类型主要为Ⅱ2—Ⅲ型,脆性矿物含量平均为49.5%,为思茅盆地页岩气有利层段。景谷洼陷南部和普文洼陷受深大断裂、地层抬升剥蚀、岩浆岩和变质岩带影响较小,盖层厚度大,页岩气保存条件相对较好。思茅盆地与相邻呵叻盆地具有相似的油气地质条件,具有一定的页岩气资源潜力,值得开展进一步的勘探研究工作。最后,综合考虑页岩分布、有机地化条件和保存条件,预测页岩气有利靶区主要位于勐班—德化及普文—象明一带。

普洱市思茅区森林生物量分层抽样调查设计分析

生物量的准确评估对于林业资源管理与碳汇评估具有重要意义。以云南省思茅区为例,运用地统计学方法分析了该区生物量的空间分布特征,并比较了不同插值与抽样方法对生物量评估的影响。结果表明:思茅区生物量具有轻微的正空间自相关性,但空间异质性较强;普通克里金法的插值效果更好;与系统抽样相比,各种分层抽样方法可以显著提高抽样精度,其中以考虑优势树种的分层抽样效果最佳。指出了对具有空间异质性的生物量开展分层抽样,可以获得比传统方法更高的评估精度,合理选择分层变量对提高抽样精度至关重要。

国土空间规划背景下区域协同发展策略——以普洱市思宁一体化为例

国内外双子城、同城化、城市群、都市圈等中大尺度区域协同发展理论和实践皆较为成熟,但当下针对小尺度区县级协同发展策略的研究有限,协同发展层次仍停滞在初级阶段。思茅区和宁洱县进行一体化发展是新发展阶段普洱市融入国家发展战略和实现高质量发展的战略选择,因此探寻有效的协同发展策略至关重要。文章在对已有区域协同发展理论进行梳理的基础上,结合《普洱市国土空间总体规划(2021—2035年)》的编制,剖析思宁两地本底优势和协同瓶颈,从空间结构、交通支撑、产业发展及人文特色4个方面制定协同发展策略,以期加快思宁一体化进程,为其他区县级协同发展提供参考。

Sr-S-K同位素示踪思茅盆地深部富钾盐体的物源

思茅盆地2350 m以深新发现了累计厚度149 m的富钾盐体。为了厘定其成钾物质来源,本文重点对15件钾石盐岩样品的Sr、K同位素和7件硬石膏岩样品的Sr、S同位素进行了分析。结果显示样品的Sr、S、K同位素均具有海水的特征,说明该盐体的成钾物质来源为海水。^(87)Sr/^(86)Sr值分别与δ^(34)S_(V-CDT)值和δ^(41)K值负相关揭示析盐期存在陆源淡水补给蒸发盆地。淡水补给导致样品的^(87)Sr/^(86)Sr值大于母源海水、δ^(34)S_(V-CDT)和δ^(41)K值小于母源海水。混源模拟计算显示钾石盐岩中淡水补给锶元素的比例为3.3%~29.2%,硬石膏岩中淡水补给锶元素的比例不超过35.2%。淡水补给Sr、S、K元素的量较少,不足以影响我们根据相应的同位素指标对盐体母质来源的识别。本项研究综合应用传统的Sr-S同位素与新兴的K同位素示踪思茅盆地深部富钾盐体的物源,为进一步研究其成因机理提供了可靠的数据支撑。

基于数字滤波和LOADEST模型的思茅河基流氮磷输出通量估算

为定量解析云贵高原地区河流基流的氮磷输出通量过程,采用最小滑动法、Chapman-Maxwell滤波法、Boughton-Chapman滤波法及递归数字滤波法对澜沧江三级支流思茅河进行了基流分割,基于LOADEST模型模拟了思茅河总径流及基流氮磷输出通量过程,估算了基流的氮磷输出贡献。研究结果表明:Boughton-Chapman滤波法对思茅河基流分割的适宜性较好,基流年均补给量约占思茅河总径流量的66%;基于LOADEST模型构建的思茅河总径流NH_(3)-N、TP输出通量模型方程判定系数R^(2)分别为81.89%和72.67%,拟合效果较好,二者年均输出通量分别为567.58 t和25.75 t;基流NH_(3)-N、TP年均输出通量分别为391.57 t和18.87 t,对思茅河总径流氮磷输出通量的年均贡献率分别为69%和73%;在做好陆域氮磷削减的同时,更要充分考虑到对基流氮磷污染的精准防控。

兰坪-思茅盆地宁洱地区新生代玄武岩地球化学特征及意义

宁洱新生代玄武岩主要分布于宁洱县城与通关周围,玄武岩覆盖在下白垩统之上,主要由橄榄玄武岩及橄斑玄武岩组成,具气孔构造,斑状结构,含有较多的斜长石斑晶。宁洱新生代玄武岩为碱性玄武岩,其特征为大离子亲石元素Ba和高场强元素Nb、Ta、Zr、Th较为富集,Ti、Al含量较高,Si含量低,轻重稀土元素分异较明显,表现出明显的Eu正异常,δEu平均值为1.34。宁洱玄武岩的地球化学特征显示其来自于陆内裂谷环境,岩浆来自于富集地幔,分离结晶作用较弱且几乎未受到地壳的混染作用。宁洱玄武岩形成于更新世时期,是兰坪—思茅盆地中轴构造活动剧烈导致新生代活动断裂相互错动,活跃岩浆迅速溢出地表的产物。区域内新生代的断裂构造具有裂谷的性质,可能处于裂谷形成的早期阶段。