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1.
Amik Lake or, historically, Lake of Antioch, was a large freshwater body in the lower Orontes River basin (Hatay Province, Turkey) that was drained in the 1940s–1970s. Several endemic animal species were described from this lake, including the freshwater mussel Anodonta pseudodopsis Locard, 1883 (Bivalvia: Unionidae) characterized by a large rounded shell covered by a peculiar yellow or yellowish-brown periostracum. Molecular analyses of topotypes of this nominal taxon collected from the former lake’s tributaries in the Amik Plain indicate that it is an intra-specific lineage of the widespread Anodonta anatina (Linnaeus, 1758) based on the mitochondrial COI and 16S rRNA, and the nuclear 28S rRNA gene fragments. Geometric morphometric analyses using the lectotype and topotypes of Anodonta pseudodopsis support our DNA-based hypothesis on the status of this nominal taxon. A new synonymy is provided as follows: Anodonta anatina = Anodonta pseudodopsis syn. nov. The syntype of Anodonta pseudodopsis SMF 5129 “See von Antiochia” (Senckenberg Research Institute and Natural History Museum, Frankfurt, Germany) is designated here to be the lectotype of this nominal taxon. Finally, we conclude that Anodonta anatina range covers the Orontes River basin in Turkey and Syria and the Nahr al-Kabir al-Shamali River in the Latakia Governorate of Syria. This intraspecific lineage of Anodonta anatina and other freshwater mussels of the Middle East are highly threatened due to multiple anthropogenic impacts and must be a focus of international conservation efforts. The Karasu River in eastern Turkey hosts viable populations of all freshwater mussel species of the Orontes’s fauna and can be considered one of the most important water bodies for the conservation of these imperiled animals in the region.  相似文献   
2.
滇西地区二叠纪—三叠纪岩浆岩展布还不清楚,导致相关古特提斯构造演化模型还存在争议。本文对兰坪-思茅盆地西缘水泄地区的辉长岩开展了LA-ICP-MS锆石U-Pb定年、锆石Hf同位素、全岩主微量元素及Sr-Nd同位素分析,探讨了岩石成因及地质意义。水泄辉长岩2件样品的锆石U-Pb年龄分别为237.8±3.4 Ma和240.8±3.3 Ma,代表其结晶年龄,属于中三叠世。样品具有较高的Na2O/K2O(3.81~49.14),明显富集Ba、Rb、Th、U等大离子亲石元素,相对亏损Nb、Ta等高场强元素,稀土元素弱分馏,轻稀土弱富集,δEu值为0.87~1.07,无明显的Eu异常。锆石εHf(t)值全为正值,主要介于+5.67~+15.75,全岩初始87Sr/86Sr比值为0.70453~0.70776,εNd(t)值全为正值,介于+4.9~+5.2。地球化学特征显示水泄辉长岩来源于亏损地幔的部分熔融,在岩浆演化过程中发生了镁铁质矿物和铁钛矿物的分离结晶作用。水泄...  相似文献   
3.
西拉木伦构造带北部双井地区发育一套巨厚的、成熟度低的快速堆积的粗碎屑沉积建造,为同造山磨拉石沉积,前人称其为克德河砂砾岩带并将其时代分别划为中二叠世(哲斯组)、晚二叠世(林西组)。本次工作对该套地层进行了大比例尺剖面测量,对取自剖面第下、中、上(1、25、86层)三个部分的砂岩样品进行LA-ICP-MS U-Pb年代学研究,结果显示:3个样品具有相似的主要年龄区间,依次为405-485Ma、401-463Ma、363-520Ma,其峰值年龄分别为427Ma、445Ma、440Ma,锆石数量分别占总量的48%、52.5%和38.75%;其次为大于1000Ma的年龄,锆石数量分别占30.7%、22.5%、45%,且均具有1800Ma和2500Ma左右的峰值年龄,明显具有华北板块基底年龄信息;自下而上3个测年样品最年轻峰值年龄分别为312Ma、376Ma,282Ma,最年轻的锆石年龄分别为304Ma、244Ma和245Ma。在第85层杂色复成分砾岩的灰岩砾石中发现晚石炭-早二叠世阿木山组的蜓和珊瑚化石,在41及43层发现中生代孢粉化石。综合碎屑锆石测年及生物化石研究结果,克德河砂砾岩带的时代应为中三叠世。推测西拉木伦构造带经历了一个较长的演化过程,中二叠世开始华北板块和西伯利亚板块进入碰撞造山阶段, 同造山磨拉石建造(克德河砂砾岩带)标志着中亚造山带演化的终止,华北板块和西伯利亚板块的碰撞拼合造山一直延续到中三叠世才结束。  相似文献   
4.
商志文  李建芬  姜兴钰  李琰  王宏 《地质学报》2020,94(8):2433-2445
大凌河河口地区LZK06孔40m以浅岩心的沉积学、古生物学和年代学等综合研究以及该地区LZK02- 04钻孔资料,揭示了研究区中更新世晚期以来经历了两次海侵- 海退旋回,依次形成了中更新世晚期湖相/河流相 SymbolnB@ 晚更新世海相- 湖相/河流相 SymbolnB@ 全新世海相- 河流相地层。全新世早中期由于物源供给很少,研究区处于长达约10ka的饥饿滞留相沉积环境,平均沉积速率仅约0. 02~0. 05cm/a。全新世晚期约1500a cal BP以来,由于人类活动导致水土流失,河流输砂量增加,研究区开始了快速加积过程,平均沉积速率约0. 9~1. 2cm/a,下辽河平原被快速充填,开始成陆。与全球海面变化时空分布特征的对比,推断辽东湾的第II海相层发育于MIS 5- MIS 3早期,第I海相层发育于MIS 1阶段高海面时期。晚更新世以来频繁的海面升降是辽东湾泥质海岸带地层和环境演化的主要控制因素。  相似文献   
5.
报道了突泉盆地南部牤牛海地区发现的植物大化石15属26种,主要包括有节类Noecalamites sp.、Equisetites sp.,真蕨类Todites goeppertianusT.williamsoniCladophlebis argutulaC.hsiehianaC.shansiensis,松柏类Pityospermum staratschiniP.nordenskioldiPodozamites schenkiP.lanceolotus,银杏类Czekanowskia rigidaGinkgo huttoniGinkgoites cf.SibiricusG.sibiricusG.cf.marginatusG.lepidusVittifoliolum paucinervePhoenicopsis speciosaSphenobailra sp.,苏铁类Nilssonia sinensis以及裸子植物花果和种子Carpolithus sp.等,其中以真蕨类(26.9%)和银杏类(38.5%)占优势,松柏类(19.2%)占一定比重,含少量的木贼类(7.7%)、苏铁类(3.8%)以及裸子植物花果和种子化石(3.8%).结合前人在该地区发现Raphaelia diamensis,指示该套含可采煤层的细碎屑岩组合具有浓厚的中侏罗世早期的时代特征,应为中侏罗世万宝组.根据植物组合中主要发育真蕨纲的Cladophlebis,银杏纲银杏目的GinkgoGinkgoitesSphenobailra以及松柏纲苏铁衫杉科的Podozamites等分子,结合当时整个万宝组植物群面貌以及地层中含煤、发育沉积铁矿等特征,可推测研究区当时具有温暖潮湿的古气候环境.  相似文献   
6.
The upper portion of the Cuyo Group in the Zapala region, south‐eastern Neuquén Basin (Western Argentina), encompasses marine and transitional deposits (Lajas Formation) overlain by alluvial rocks (Challacó Formation). The Challacó Formation is covered by the Mendoza Group above a second‐order sequence boundary. The present study presents the stratigraphic framework and palaeophysiographic evolution of this Bajocian to Eo‐Calovian interval. The studied succession comprises the following genetic facies associations: (i) offshore and lower shoreface–offshore transition; (ii) lower shoreface; (iii) upper shoreface; iv) intertidal–subtidal; (v) supratidal–intertidal; (vi) braided fluvial to delta plain; (vii) meandering river; and (viii) braided river. The stratigraphic framework embraces four third‐order depositional sequences (C1 to C4) whose boundaries are characterized by the abrupt superposition of proximal over distal facies associations. Sequences C1 to C3 comprise mostly littoral deposits and display well‐defined, small‐scale transgressive–regressive cycles associated with fourth‐order depositional sequences. Such high‐frequency cycles are usually bounded by ravinement surfaces associated with transgressive lags. At last, the depositional sequence C4 delineates an important tectonic reorganization probably associated with an uplift of the Huincul Ridge. This is suggested by an inversion of the transport trend, north‐westward during the deposition of C1 to C3 depositional sequences (Lajas Formation) to a south‐west trend during the deposition of the braided fluvial strata related to the C4 depositional sequence (Challacó Formation).  相似文献   
7.
This study presents new zircon U–Pb geochronology, geochemistry, and zircon Hf isotopic data of volcanic and subvolcanic rocks that crop out in the Bayanhushuo area of the southern Great Xing’an Range (GXR) of NE China. These data provide insights into the tectonic evolution of this area during the late Mesozoic and constrain the evolution of the Mongol–Okhotsk Ocean. Combining these new ages with previously published data suggests that the late Mesozoic volcanism occurred in two distinct episodes: Early–Middle Jurassic (176–173 Ma) and Late Jurassic–Early Cretaceous (151–138 Ma). The Early–Middle Jurassic dacite porphyry belongs to high-K calc-alkaline series, showing the features of I-type igneous rock. This unit has zircon εHf(t) values from +4.06 to +11.62 that yield two-stage model ages (TDM2) from 959 to 481 Ma. The geochemistry of the dacite porphyry is indicative of formation in a volcanic arc tectonic setting, and it is derived from a primary magma generated by the partial melting of juvenile mafic crustal material. The Late Jurassic–Early Cretaceous volcanic rocks belong to high-K calc-alkaline or shoshonite series and have A2-type affinities. These volcanics have εHf(t) and TDM2 values from +5.00 to +8.93 and from 879 to 627 Ma, respectively. The geochemistry of these Late Jurassic–Early Cretaceous volcanic rocks is indicative of formation in a post-collisional extensional environment, and they formed from primary magmas generated by the partial melting of juvenile mafic lower crust. The discovery of late Mesozoic volcanic and subvolcanic rocks within the southern GXR indicates that this region was in volcanic arc and extensional tectonic settings during the Early–Middle Jurassic and the Late Jurassic–Early Cretaceous, respectively. This indicates that the Mongol–Okhotsk oceanic plate was undergoing subduction during the Early–Middle Jurassic, and this ocean adjacent to the GXR may have closed by the Late Middle Jurassic–Early Late Jurassic.  相似文献   
8.
Water Flows Toward Power: Socioecological Degradation of Lake Urmia,Iran   总被引:1,自引:0,他引:1  
Water is an invaluable resource, and equitable access to it is a fundamental human right. Disenfranchised groups often lose access to water resources because their interests are not well represented by decision makers. Excluding these groups from resource management policy often results in myopic decisions that contribute to further ecosystem damage. We describe the ecological degradation of Lake Urmia in Iran, which has recently experienced increased salinity and declining water quantity. The lake is a UNESCO Biosphere Reserve and Ramsar site, and supports unique biodiversity in the region. The lake's decline is driven by the destruction of Zagros forests and the government's water policies, which diverted water to more politically connected agricultural land users, increasing social inequity and prompting more deforestation. The most straightforward restoration solution is to discontinue the diversions and allow critical inflows to recharge Lake Urmia, preserving the lake and wetlands for migratory birds, tourists, and local communities.  相似文献   
9.
高岭岩体位于吉林省延边地区和龙市东侧,大地构造位置上位于华北板块北缘东段,岩性主要为似斑状二长花岗岩,基质为中粒-中细粒结构。LA-ICP-MS锆石U-Pb测年结果显示,样品YH04和N-5的加权平均年龄分别为172.25±0.97Ma和170.9±0.68Ma,表明岩体侵位时代为中侏罗世。岩石地球化学特征上,高岭岩体样品具有高硅(69.60%~74.30%)、富铝(13.90%~15.80%)、富钾(3.05%~4.50%)和低镁(0.22%~0.82%)及Mg#(26~37)的特点。样品富集轻稀土元素,相对亏损重稀土元素(LREE/HREE=13~21),具有微弱的负Eu到正Eu异常(δEu=0.78~2.14),其稀土元素配分模式图与埃达克岩稀土元素配分模式图类似。高岭岩体样品富集大离子亲石元素Cs、Rb、Ba、K、Sr和高场强元素Th、U和Zr,同时亏损高场强元素Nb、Ta以及P元素。同时样品具有较低的初始87Sr/86Sr值(0.7039~0.7051)和负的εNd(t)值(-0.6~-0.3),且其t DM1和t DM2模式年龄分别为922~928Ma和984~1011Ma,表明研究区新元古代存在地壳增生事件。Sr-Nd同位素特征及岩石地球化学特征表明高岭岩体母源岩浆来源于加厚下地壳基性岩石部分熔融且受到了新元古代增生物质的影响。结合区域构造演化,中侏罗世高岭岩体侵位构造环境可能受到环太平洋构造体系和华北板块与西伯利亚板块持续碰撞的叠加影响。  相似文献   
10.
Although the evidence of insect oviposition on plant organs has been reported from the late Paleozoic to the Miocene, record from the middle Jurassic is still blank. This paper reports a significant evidence of insect oviposition on plant leaf from the middle Jurassic for the first time. The ovipositional scar is distributed on the abaxial surface of Sphenobaiera leaf(Ginkgoales) from the middle Jurassic Daohugou Formation of Inner Mongolia, China. A new ichnospecies Paleoovoidus venustus sp. nov. is described. The scar is elliptic to oval, arranged in longitudinal rows between leaf veins with almost regular distance, with its long axis paralleling to the leaf venation. This discovery adds new information to the morphology of insect endophytic oviposition probably produced by Odonata existed in a terrestrial ecosystem ~165 Ma ago. The new materials also provide important data for the study of insect reproductive biology, plant-insect interaction and coevolution, as well as understanding the paleoclimate and palaeoenvironment during that time in northeast China.  相似文献   
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