Genesis of lower strain S-L-type tectonitesin Daqingshan area, Inner Mongolia

Usual ductile shear zone has relatively high strain magnitude. However,for high-grade metamorphic rocks in Daqingshan area,the related strain is very low with weakly developed lineation. Significantly,the finite strain type with a K-value slightly lower than 1 and is characterized by compressional strain. Because the special tectonic environment with high temperature,the percentage of melt is relatively higher,which leads to a series of microscopic phenomenon such as multi-grain quartz bands,feldspar three edges equilibrium-like texture,granular flow,etc. As a consequence,the tectonites in the studied area illustrate a unique character: obvious rheological meso-deformation structure but with very weak intracrystalline micro-deformation.

The Formation, Movement and Evolution Pattern of Jurassic Terrestrial Deposit Basin in Daqingshan Region

The authors have reconstructed the original shape of Jurassic basin in Daqingshan region and discussed the movement and evolution pattern of the basin. The basin developed between Paleozoic strata sliver and metamorphic rock sliver in late stage of Early Jurassic and extended in latitude direction. The paleo-terrene of the basin is higher in north and west than south and east. The boundary of basin is largest in Changhangou stage of Middle Jurassic. After middle Jurassic, the region took place Yenshan movement, and then the basin changed obviously from weakly extending environment of Early and Middle Jurassic to extruding environment of late Jurassic, and the paleoclimate of the basin changed from warmth and wetness to dry. The basin finished the evolution history in the late stage of Late Jurassic with the development of thrust.

Characteristics of Ore-Forming Fluids of Gold Deposits in Daqingshan District,Inner Mongolia,China

<Abstract>Locatedinthemid-westoflimerMongolia.Daqingshandistricthasmanygolddepositsoccurringalongaeast-weststrikingductileshearzonewithinagreelt,whichismainlycomposedoftheArcheanWulashangroup.Thehydrothermalmineralizationcanbedividedintofourstages:(1)pyrite-quartz,(2)quartz-Pyrite,(3)polymetallicsulfidesand(4)carbonates-quartz.Themajormetalylicmineralsintheoreofgold-bearingveinsarenativegold,electrum,pyrite,chalcopyriteandgalena,buttheganguemineralsaremainlyquartz,secondarilysericite,ankeriteandexcite.Prinipalalterationpatternsinthegolddepositsaresericithation,silicification,pyritizationcarbonatizationandchlorization.Aninvestigationonfluindinclusionsshowsthattheore-formingfluidswerelowinsalinitieandhighinCO2content,MeasuredδDoffluidinclusionsinquartzfromtheoreveinsrangesfrom-65‰to-104‰,butδ18Oquartzfrom10.0‰to12.8‰.Thesedatashowthatthewaterinhydrothermalfluidprecipitatingtheorebodiescouldhavebeenmainlymagmaticwaterandmetamorphicwaterbutlocalmeteoricwatermighttakepartinthelatemineralization.δ13Cfromfl

Sinistral Strike-slip Movement Along Western Terminal Segment of the Active Daqingshan Piedmont Fault, Inner Mongolia, China

There are 18 gullies displaying sinistral contortions to different degrees along the western terminal segment about 10 km long of the active Daqingshan piedmont fault near the Donghe District, Baotou City. The contortion amount of gullies ranges from 20 m to 300 m. The contortion and length of the gullies are in direct proportion. The relation between piedmont terraces and gullies indicates that the gullies with upper reaches of about 1 ～ 5 km long and those smaller than one kilometer were formed at the end of Late Pleistocene and Holocene.Meanwhile, sandy gravel layer of alluvial-proluvial sediment on the upthrown wall is directly in contact with yellow clayey sand of the downthrown wall. During the Holocene, the sinistral strike-slip rate along the western terminal segment of the active Daqingshan piedmont fault reached 5 mm/a from age data of dislocated sediments. The evolutional mechanism of the active Daqingshan piedmont fault is also discussed in the paper.

A Plate-Tectonic Model for the Evolution of the Daqingshan Granulite belt in Inner Mongolia

One of the most important events in the early geological evolutionary history of the Earthwas the wide occurrence of granulite belts at the end of the Archaean in the world, whichmeans a possible transformation of evolution mechanism of the crust. More and more geo-

History of Paleoseismic ActivityAlong the Hohhot Segment of Daqingshan Piedmont Fault in the Late Quaternary

A detailed study on geomorphic surfaces and a set of trenches on the Hohhot segment of Daqingshan piedmont fault at three sites, Kuisu, Ulan Blang, and Qingshan Grassland, revealed 7 paleoseismic events occurred along the fault segment since 19 ka BP. Those events occurred at 18.75±.75 ka, 16.97 ±.96 ka, 14.65±.67 ka, 11.82±.69 ka, 9.45±.26 ka, 6. 83±.26 ka, and 4. 50 ±0. 23 ka BP, respectively, and their average recurrence interval is 2375±432 years. From the results of constraining fault displacement and correlation between the sediments in these trenches, we found a complete paleoseismic activity history along the fault segment during this period of time.

内蒙古大青山-盘羊山晚中生代-早新生代构造事件及其对华北北缘构造演化的启示

内蒙古大青山和盘羊山位于华北克拉通北缘,其复杂的地质构造对华北克拉通北部中—新生代构造演化具有重要的指示作用。大青山以北的盘羊山逆冲体系,形成于晚二叠世至早三叠世古亚洲洋的闭合,晚侏罗世可能受蒙古-鄂霍次克洋闭合的影响而重新活动。大青山地区发育4期中—新生代变形构造,从老至新依次是:SE-NW向伸展形成的呼和浩特变质核杂岩、NW向逆冲的大青山逆冲体系、以不变形花岗岩为核心的构造穹窿、大青山山前断裂及高角度正断层。发生于约142~132 Ma的SE-NW向伸展,形成于造山增厚地壳的重力垮塌,并形成呼和浩特变质核杂岩和相关的拆离体系。大青山逆冲体系形成于约130~120 Ma,代表造山过程中地壳荷载与板块汇聚的抗衡导致的构造反转,另一可能是古太平洋俯冲的远程效应。自约120 Ma以来,大青山处于一个构造-热松弛期,导致该区约120~90 Ma的冷却事件被广泛记录,并形成以不变形花岗岩(约114 Ma)为核心的穹窿构造;这些事件可能与华北克拉通的峰期破坏相关。大青山山前断裂和相关的高角度正断层开始于始新世,可能是印度-欧亚大陆碰撞和太平洋板块运动方向改变的远程效应所致。古亚洲洋和蒙古-鄂霍次克洋的闭合导致华北克拉通北缘地壳增厚,引发早白垩世造山晚期的垮塌和伸展,形成呼和浩特变质核杂岩。自120 Ma开始,大青山开始受华北克拉通破坏的影响,并形成后造山伸展。新生代,大青山受新特提斯和太平洋构造域的远程影响。

内蒙古大青山侏罗纪沉积盆地充填和构造古地貌重建

石拐盆地是阴山地区保存最完整的侏罗纪盆地,其沉积充填过程和碎屑物质组成为正确认识大青山侏罗纪构造地貌演化提供了重要约束。石拐盆地形成于伸展断陷环境,依次充填了下侏罗统五当沟组和中侏罗统召沟组。断陷初期,南部地貌陡峭,控制发育了冲积扇沉积体系,碎屑组分记录了近源高级变质地体的剥露过程;晚期以坳陷为主,在召沟组末期形成最大湖泛面,碎屑组分中沉积岩岩屑和砾石明显增多,指示构造平静阶段的地貌夷平。至中—晚侏罗世,大青山地区构造属性发生反转,断陷盆地南部开始卷入挤压变形,形成大青山褶皱—逆冲系统雏形。然而,这些新生的挤压构造似乎未能引起地表地形的剧烈起伏,它们主要表现为隐伏状态。相反,该时期北部地貌抬升最为显著,不仅体现在中侏罗统长汉沟组和上侏罗统大青山组边缘相沉积均分布在盆地北部,更体现在阴山地体中浅层次盖层、火山物质与深层次TTG岩套的的反复剥露抬升。这种“北高南低”地貌特征的形成与阴山地体持续抬升及其两侧先存断裂活化密切相关,也是对周缘板块向东亚大陆俯冲汇聚的远程响应。

大青山山前断裂土右旗西段莲花山探槽揭露的古地震事件及年龄

大青山山前断裂位于河套盆地北缘,晚第四纪以来活动强烈,前人对该段古地震特征做过较多研究,但是因测年技术手段限制,以及在同一断层剖面拥有较多能有效约束古地震事件的测年数据较少、且能揭露出较多古地震事件的剖面偏少。本文通过对大青山山前断裂土右旗西段莲花山东侧古地震探槽的开挖,利用光释光年代学数据对古地震事件进行有效约束,并结合前人在该段探槽的年代数据,运用断层逐次限定法综合分析,得出土右旗西段断裂距今约11 500年发生了5次古地震事件,平均复发间隔2 260年。该段断裂5次古地震事件由新到老分别为:1.28~1.42 ka、3.41~3.60 ka、4.08~5.01 ka、8.26~9.32 ka和10.70~11.30 ka。最新一次活动事件应该为公元849年地震。同时,探槽揭露该段断层呈正断层性质,倾角在∠58°~∠77°之间。根据经验公式,包头段、土右旗西段和土左旗西段的潜在发震能力分别在M_W6.8~7.1、M_W6.8~7.1和M_W7.1~7.2左右。本文经验公式得出的震级偏小,可能存在级联破裂,后期需进一步结合其他手段对大青山山前断裂西段的危险性进行综合评价。

Evidence of microstructures and fluid inclusions for the origin of polycrystalline quartz ribbons in high-grade metamorphic rocks in Daqingshan region

Polycrystalline quartz ribbons in high-grade metamorphic rocks from the Daqingshan region, are typi- cal microfabrics of, and provide information for, deep crust deformation and metamorphism. The quartz ribbons have straight boundaries and extend stably along gneissosity. They truncate other mineral grains in the rocks and may contain inclusions of such minerals that are lens-shaped and oriented. They frequently end into branching termination. Analysis fluid inclusions in polycrystalline quartz rib- bons reveal that the complex types of fluid inclusions are inhomogeneously distributed. They are ob- viously different from inclusions captured at granulite facies, in both fluid compositions and T-P esti- mations. Based on microfabric and fluid inclusion analysis, the polycrystalline quartz ribbons are suggested to be formed by SO2-rich fluids filling micro-fractures that are parallel to early gneissosity. The SO2 composition is derived from the deformed host rocks. The fluid phase has significant effects on the rheological characteristics, fracturing of rocks, and formation of quartz ribbons.

Responses of Stream Geomorphic Indices to Piedmont Fault Activity in the Daqingshan Area of China

A recent correlation of stream geomorphic indices to fault activity has revealed that stream geomorphologies in bedrock mountain areas are good records of local fault movements. The Daqingshan piedmont fault is one of the main active faults in the fault system on the northern margin of the Hetao Basin and has produced frequent large-scale earthquakes since the Late Pleistocene. In the present study, following the segmentation regime of previous studies, we divide the fault zone into five segments, namely, the Baotou, Tuyouqi West, Tuzuoqi West, Bikeqi, and Hohhot segments, and we discuss the relationship between the drainage basin geomorphology and the piedmont fault activity in the Daqingshan area using 30 m spatial resolution Shuttle Radar Topography Mission(SRTM) digital elevation model(DEM) data. We use a range of geomorphic indices to examine the drainage basins in the Daqingshan area, including the channel steepness index(ksn), slope, hypsometric integral(HI), relief degree of land surface(RDLS), and stream lengthgradient index(SL), extracted with ArcGIS and MATLAB, and we also consider local lithologic and climate aspects. Furthermore, we compare the geomorphic indices with the slip rates of individual segments of the Daqingshan piedmont fault and paleoseismic data. The results show that the geomorphic indices of drainage basins in the Daqingshan area are primarily affected by the piedmont fault activity in the Daqingshan area. The geomorphic indices also demonstrate that piedmont fault activity has been the most intense in the middle segment of this fault system since the Late Quaternary and decreases towards the two sides.

复杂山区地表温度模拟及影响——以内蒙古大青山为例

地表温度(LST)是影响植物分布和生态系统过程的重要因素。本研究利用天气研究与预测模式(WRF)模拟大青山保护区的高时空分辨率LST,通过气象站点观测值和MODIS LST值对比验证模拟结果的准确性,并通过综合影响因素和单一影响因素分析LST与环境因子之间的关系。综合影响因素分析是基于区域模拟LST和区域环境因子进行的分析;单一影响因素分析是首先固定其他环境因子,然后分析LST和单一环境因子的关系。结果表明:模拟值与3个站点观测值相关系数均超过0.97(P<0.001),与MODIS LST空间相关性为0.73(P<0.05),表明WRF在山区有很好的实用性。经综合影响因素分析,年均LST与高程的相关性最大(R>0.97),与2 m气温和2 m水汽混合比次之(R>0.8),与植被覆盖度和坡度较小(R>0.3),其他因素影响微弱。经单一影响因素分析,在春夏秋冬4个季节,随高程升高LST下降速率分别为0.83 K·(100m)^(-1)、0.79 K·(100m)^(-1)、0.80 K·(100m)^(-1)、0.32 K·(100m)^(-1);坡度每增加10°,LST在春夏秋冬分别升高-0.05 K、0.17 K、-0.14 K、0.02 K;植被覆盖度每增加10%,LST在夏冬两季分别升高0.31 K、1.41 K,其他季节则没影响;坡向对4个季节平均LST的影响均为南>西南>东南>西>东>西北>东北>北;年均LST与2 m水汽混合比呈对数关系,与2 m气温呈指数关系。研究结果可为大青山自然保护区管理提供基础数据,也为山地研究提供可借鉴的方法。

^40Ar/^39Ar dating of Daqingshan thrust

The Daqingshan thrust system, to the south of the Shiguai Mesozoic basin, is a complex system of top-to- the-north thrusting tectonic sheets. The thrust system has a complicated evolution due to multi-stage thrusting. In order to date the thrusting events, syntectonic muscovite and bio-tite grains are respectively analyzed with normal 40Ar/39Ar dating and laser 40Ar/39Ar dating, which yield 2 isochron ages, i.e. 193.74 3.88 Ma and 121.6 1.6 Ma. These ages suggest that faults within the Daqingshan thrust system formed dur-ing 2 stages of thrusting, one the early Indosinian and the other the late Yanshanian. The isotopic dating is consistent with field geological relations. Indosinan deformation is evi-denced by top-to-the-north thrusting, with the occurrence of a series of large-scale east-west trending thrust faults and folds, while the Yanshanian thrusting is characterized by top-to-the-NNW thrusting. It is superposed on and modifies early Indosinian thrust faults.

华北克拉通北缘孔兹岩带两期深熔石榴花岗岩地球化学特征及其地质意义

华北克拉通北缘孔兹岩带大青山地区和集宁—凉城地区石榴花岗岩与深熔源岩(泥质片麻岩)在野外空间上渐变过渡、密切共生。石榴花岗岩中含有大量的源岩包体、残留体、残留矿物相/转熔矿物相,深熔源岩中也存在大量的石榴花岗岩团块,这些混合岩的岩性在宏观上具有不均一性。岩相学研究表明,石榴花岗岩与泥质片麻岩矿物组成相近,二者具有特征十分相似的石榴石,主要为残留矿物相/转熔矿物相。地球化学研究表明,石榴花岗岩与泥质片麻岩拟合程度较好,均具有高TFeO/MgO值和Al_(2)O_(3)质量分数,K_(2)O/Na_(2)O值和CaO质量分数存在较大变化,相对富集轻稀土元素和大离子亲石元素,相对亏损Ta、Nb、Ti和P等元素。与世界上典型的S型花岗岩成分偏离,大青山地区和集宁—凉城地区石榴花岗岩具有低SiO_(2)质量分数(50.30%~73.10%)和高MgO+TFeO质量分数(1.6%~14.8%)。研究认为偏离正常S型花岗岩的成分范围与石榴石残留体带入和幔源物质添加有关。结合前人资料,认为大青山地区和集宁—凉城地区石榴花岗岩由2.45~2.37 Ga和1.95~1.90 Ga两期深熔事件形成,与区域上幔源岩浆底侵时代相近,指示大青山地区和集宁—凉城地区石榴花岗岩是幔源基性岩浆侵入麻粒岩相变质沉积岩中引起变沉积岩发生大规模部分熔融的产物。

新疆哈密大青山金矿床成矿期构造特征及找矿方向

东天山-北山金矿集区是我国重要的金矿集区之一。近年来,该矿集区东部的大青山金矿综合运用多种勘查方法,取得了显著的找矿成果。为了查明成矿期构造特征,进一步指导找矿,通过对已取得勘查资料的综合整理及矿区成矿构造的详细观测解剖,采用野外观察与室内分析相结合、宏观与微观相结合的研究方法,对控矿结构面、成矿期的构造特征及矿体分布规律进行研究。研究表明:大青山金矿床主矿体均位于NEE走向的压扭性逆断层中,主含矿断层受控于矿区北西部的F13;主矿体具有薄而富、尖灭再现的特征,整体向SW侧伏,矿体围岩蚀变强烈,主要为绢云母化、绿泥石化、碳酸盐化;成矿期构造应力场为NW-SE方向挤压,自现有矿体向SW寻找深部新矿是有意义的。

大青山山羊肉品质特点及其产业发展前景

大青山山羊是自然散养放牧,多以丰富的野生植被为食,使其具有适应性强、觅食能力强、抗病力高等特点。本文对大青山山羊肉的营养特征、质量指标和风味特点进行了综述,发现其肉质细嫩、蛋白质含量高、脂肪含量低、营养价值高,最佳宰杀年龄为2.5~3.5岁。依据大青山山羊肉风味浓郁、嚼劲十足等特点,围绕大青山山羊肉的价值优势和经济优势,提出了加强品牌建设、加快山羊肉产品开发、加快电商销售力度、建立健全的追溯系统等发展新思路,以期为更好地促进大青山山羊肉产业发展提供支持。

阴山山脉大青山星象岩刻遗址调查简报

2021年3月11日至2022年5月1日,内蒙古鸿德文理学院中国北方岩画研究所、内蒙古师范大学历史文化学院、内蒙古自治区文物考古研究院组成联合调查队,普查了阴山山脉大青山星象岩刻遗址。此次调查共发现三组16个杯壮星穴岩画,岩画刻磨在富含石英晶体的板岩之上,凹穴最大直径8厘米,最小3厘米,深度1.5~3厘米,制作方法均为先用砾石凿錾后期钻磨,制作十分精细,经过精准测量,排列有序的杯壮星穴形制,酷似南天三星系及北天北斗星系。经过科学的微晶体透视测年,两处星座制作时期为4620-5488年。这一发现为中华民族早期记载天象轨迹研究、天文观的形成研究,天象与季节、天象与时运关系的研究提供了较为珍贵的第一手资料。

大青山国家级自然保护区珍稀濒危保护种子植物组成及区系特征

【目的】厘清大青山国家级自然保护区珍稀濒危保护种子植物组成及区系特征,为该自然保护区种子植物资源的有效保护与合理开发利用提供参考。【方法】基于野外调查数据及文献资料,形成大青山国家级自然保护区珍稀濒危保护种子植物名录,并通过区系研究方法对其区系地理成分进行分析。【结果】大青山国家级自然保护区共有珍稀濒危保护种子植物53种,隶属24科38属,其中,国家二级重点保护野生植物12种、内蒙古珍稀濒危保护植物22种、内蒙古珍稀林木29种。种子植物的生活型以木本植物为主,共29种,占大青山国家级自然保护区珍稀濒危保护种子植物总种数的54.7%;草本植物23种,占总种数的43.4%。水分生态型以中生植物为主,共43种,占总种数的81.1%。植物区系以华北分布种和东亚分布种为主。【结论】大青山国家级自然保护区区系地理成分较为丰富,具有明显的温带性质,反映了大青山植物区系的特征。

公元849年内蒙古包头地震补充研究

公元849年10月20日(唐宣宗大中三年十月辛巳),在内蒙古包头附近发生了一次大地震,造成城堡、军营和民房破坏等严重震害和数千人死亡。目前对本次地震的震中位置、烈度和震级等基本参数认识尚存疑。通过对相关史料的系统梳理,重点对位置存疑的云伽关或云伽镇等进行进一步分析论证,重新核定了主要破坏地点及其地震烈度,修绘了地震等震线图,校核了地震震级、震中位置等基本参数。结果表明,公元849年地震等震线呈不对称的纺锤形,长轴方向为近东西向,短轴呈近南北向,极震区烈度可达X~X+度,震中位置大约在今内蒙古包头市附近,即40.6°N、110.3°E,震级达(7.8±0.3)级或7级。其中,等震线南侧地震影响范围大(包括河套盆地及其以南较大区域)、震害重、烈度衰减慢,而北侧几乎无震害记载,地震烈度衰减快,影响范围小。本次地震烈度等震线属于典型的正断层地震类型,其发震构造为大青山山前断裂中西段。文章依据历史地震史料校核结果与前人基于活动断裂研究结果所确定的震中位置和震级大致相当。综合研究认为鄂尔多斯北缘发生的公元849年地震震级约为7级,该区未来地震震级上限及其大震风险值得继续深入研究。

广西大青山南亚热带马尾松、杉木混交林生态系统碳素积累和分配特征

选取广西大青山3个13年生马尾松、杉木混交林样区,研究其生态系统的碳素积累和分配特征.结果表明,混交林中两个树种的碳素含量各异.马尾松干、根、枝的碳素含量较高,分别为58.6%、56.3%、51.2%,叶和皮含量较低,变化幅度为46.8%～56.3%.各器官中按碳素含量的高低排列顺序为：干＞根＞枝＞皮＞叶;杉木皮、叶、干的碳素含量较高,分别为52.2%、51.8%、50.2%,碳素含量从高到低依次为：皮＞叶＞干＞根＞枝.从两个树种各器官碳总含量来看,马尾松要高于杉木.灌木层、草本层及地表凋落物层碳素平均含量分别为44.1%、33.0%及48.3%.土壤3个层次（60cm深）碳素含量为1.45%～1.84%,各层次碳素含量分布不均,表层（0～20cm）土壤碳素含量较高.针叶混交林乔木层生物量（t·hm^-2）为85.35～101.35,平均为93.83,且均以马尾松生物量居多（占75.7%～82.6%）.混交林生态系统碳库的空间分布序列为土壤层＞植被层＞凋落物层.植被层的碳贮量平均为51.91t·hm^-2,占整个生态系统碳总贮量的29.03%;乔木层碳贮量占整个生态系统的23.90%,占植被层碳贮量的97.7%.乔木层碳贮量中,马尾松占的比例较大,为65.39%.碳贮量在两个树种各器官中的分配,基本与各自的生物量成正比例关系,树干的碳贮量均最高,马尾松、杉木的树干碳贮量分别占各自碳贮量的53.23%、55.57%,树干的碳总贮量占乔木层碳总贮量的54%.其次,两个树种根也占较大比例,树根碳总贮量占乔木层碳总贮量的19.22%.马尾松、杉木枝、皮在各自碳的贮量中分配不同,马尾松枝占的比例要大于皮,而杉木则相反;凋落物层碳贮量平均为3.25 t·hm^-2,仅占1.82%;林地土壤层（0～60cm）碳贮量是相当可观的,平均为123.43 t·hm^-2,占69.02%.马尾松、杉木混交林年净生产力为11.46t·hm^-2·a^-1,有机碳年净固定量为5.96 t·hm^-2·a^-1,折合成CO2的量为21.88 t·hm^-2·a^-1.