西南天山托云地区白垩纪-早第三纪玄武岩地球化学及其成因机制

托云玄武岩主要分布于托云盆地东侧，按形成时代可分为白垩纪玄武岩和早第三纪玄武岩。白垩纪玄武岩包括早白垩世玄武岩和晚白垩世玄武岩，以碱玄岩和碱性橄榄玄武岩为主，碱性程度高；早第三纪玄武岩包括早第三纪玄武岩及脉岩，以碱性橄榄玄武岩、碱性橄榄辉绿岩为主，碱性程度低。所有岩石稀土元素(REE)、微量元素分布模式相似，REE均为向右陡倾型，富集不相容元素。白垩纪玄武岩的∑REE、Rb、Ba、Th、K、Sr、Nb和Ta等元素富集程度均高于早第三纪玄武岩，相容元素富集程度大体较低。微量元素和同位素特征显示，玄武岩起源于与洋岛玄武岩源区相似的富集地幔源。玄武岩中赋存有交代地幔捕虏体，这表明玄武岩浆可能是交代地幔经不同程度部分熔融的产物。微量元素的特征同时显示，早白垩世玄武岩部分熔融程度较低，早第三纪玄武岩部分熔融程度较高，且在不断的部分熔融过程中，形成的岩浆又有结晶分异作用发生。托云玄武岩形成于大陆板内拉伸环境，在形成过程中经历了较弱的壳幔相互作用。     

大别山沙村和椒子岩基性-超基性岩锆石U-Pb定年、元素和碳氧同位素地球化学研究

对大别山北部沙村和椒子岩基性 -超基性岩进行了锆石U Pb定年、全岩主量和微量元素分析 ,全岩和单矿物氧同位素分析以及全岩碳含量及其同位素组成的测定。结果表明 ,这些基性 -超基性岩表现出强烈的轻稀土富集 ,高场强元素 (Nb ,Zr和Ti)负异常以及Pb和Ba正异常。锆石U Pb年龄指示了早白垩世 (12 2～ 12 8Ma)的岩浆结晶年龄 ,但是在 10 5～ 116Ma期间受到了热液蚀变。全岩和单矿物氧同位素比值变化较大 (全岩 :1.1‰～ 6 .6‰ ,单斜辉石 :3.85‰～5 .7‰ ,斜长石 :2 .8‰～ 7.3‰ ,锆石 :3.85‰～ 6 .0 4‰ ) ,大多数锆石具有与正常地幔锆石 ((5 .3±0 .3)‰ )不同的δ18O值 ,部分样品矿物对之间保存了氧同位素平衡分馏 ,而部分样品则表现出明显的氧同位素不平衡分馏 ,指示它们受到了岩浆期后亚固相水 -岩相互作用的扰动。全岩碳含量和同位素组成具有较大的变化范围 ,分别为 0 .0 3%～ 0 .18% ,δ13 C值为 - 2 7.0‰～ - 5 .8‰。将这些中生代基性 -超基性岩的元素和同位素数据与大别 -苏鲁榴辉岩比较后发现 ,它们之间具有较为一致的地球化学特征 ,因此可能具有一定的成因联系。这些榴辉岩的原岩为基性火成岩 ,对应于扬子板块北缘与新元古代裂谷构造有关的岩浆活动。古老富集岩石圈地幔及其上覆地壳部分     

祁连党河南山北坡中-基性火山岩地质特征及时代

根据地质研究、区域对比，结合首次获得的Rb-Sr等时线年龄数据，从祁连党河南山(又称乌兰达坂山）北坡原中奥陶统地层中厘定出晚震旦纪中－基性火山岩系。根据这一新成果，认为该区中基性火山岩，斜长角闪岩基底以及侵入其中的扎子沟等花岗闪长岩岩基在大地构造分区上应划归中祁连地块；晚震旦纪该区无疑有过扩张、地壳减薄的地质事件，震旦纪晚期有过挤压闭合事件。     

大别山北部榴辉岩的退变质特征及其地质意义

研究了大别山北部榴辉岩的变质岩岩石学。结果表明，该区榴辉岩相变质作用可分为早期(超高压)和晚期(高压)两个阶段，并在折返过程中形成了一系列特征性的退变质显微构造。其中，退变质结构主要包括：(1)由于压力降低而出溶形成的一些定向针状或叶片状矿物包裹体，如钠质单斜辉石中石英及石榴子石中的金红石、单斜辉石和磷灰石等；(2)冠状体或后成合晶，特别是石榴子石外围发育两期(“双层”)后成合晶；(3)反应边或退变边，如绿辉石的透辉石退变边、透辉石的角闪石退变边和金红石的钛铁矿退变边等。这些退变质结构为本区榴辉岩高级变质岩的快速折返过程和抬升历史提供了强有力的岩石学依据；石榴子石中针状矿物出溶体进一步证明研究区榴辉岩早期经历了超高压变质作用，峰期变质压力应大干4．0GPa，甚至可能达到5～7GPa或更高。     

Ice-distal Upper Miocene marine strata from inland Antarctica

ABSTRACT Glacimarine strata of the Battye Glacier Formation (≈ 130 m thick), Pagodroma Group, exposed in the Amery Oasis of East Antarctica, provide a record of Late Miocene palaeoenvironmental conditions in an ice‐distal setting. The formation overlies the Amery Erosion Surface (≈ 300 m to ≈ 270 m above sea level) that formed during an advance of the Lambert Glacier into Prydz Bay (ODP Site 739), at least 750 km further north than today. Two lithological members: a grey and muddier Lower Member and a brown, sand‐rich Upper Member, reflect variation in proximity to the terminus of the Lambert Glacier. Ice‐distal, glacimarine, diatom‐bearing mud (up to 12% biogenic silica) and in situ articulated molluscs occur in the Lower Member. The Battye Glacier Formation is significant because of its inland location, which indicates that ice‐distal marine conditions existed 250 km inland from the current Amery Ice Shelf edge. Similar Neogene strata are known on land only from the Pliocene Sørsdal Formation in the Vestfold Hills, near the Antarctic coast. Three stratigraphic intervals of diatom‐bearing mud are recognized from glacially reworked clasts and from in situ strata informally referred to as the McLeod Beds and ‘Bed A’. The diatom‐bearing mud also contains sponge spicules and minor silicoflagellates and ebridians. Marine diatom biostratigraphy constrains the age of the beds to between 10·7 and 9·0 Ma (late Miocene). Abundant benthic diatoms suggest deposition within shallow euphotic waters. The high abundance of intercalary valves of Eucampia antarctica from an interval of the McLeod Beds suggests that there was less winter sea‐ice than in Prydz Bay today. It is unlikely that sea‐ice was perennial because the presence of Thalassionema spp. and Stellarima stellaris (Roper) Hasle et Sims suggests that summer sea‐surface temperatures were too warm (> 0°C and > 3°C respectively). The palaeoclimate at the time of deposition appears to have been analogous to that in modern fjords of East Greenland (e.g. Kangerdlugssuaq Fjord), which is consistent with the depositional model proposed previously for the Pagodroma Group. The three diatom‐bearing mud intervals were deposited in the Amery Oasis, ≈ 250 km inland of the current Amery Ice Shelf edge, when the East Antarctic Ice Sheet was reduced in size relative to today.     

Intraplate mountain building in response to continent–continent collision—the Ancestral Rocky Mountains (North America) and inferences drawn from the Tien Shan (Central Asia)

The intraplate Ancestral Rocky Mountains of western North America extend from British Columbia, Canada, to Chihuahua, Mexico, and formed during Early Carboniferous through Early Permian time in response to continent–continent collision of Laurentia with Gondwana—the conjoined masses of Africa and South America, including Yucatán and Florida. Uplifts and flanking basins also formed within the Laurentian Midcontinent. On the Gondwanan continent, well inboard from the marginal fold belts, a counterpart structural array developed during the same period. Intraplate deformation began when full collisional plate coupling had been achieved along the continental margin; the intervening ocean had been closed and subduction had ceased—that is, the distinction between upper versus lower plates became moot. Ancestral Rockies deformation was not accompanied by volcanism. Basement shear zones that formed during Mesoproterozoic rifting of Laurentia were reactivated and exerted significant control on the locations, orientations, and modes of displacement on late Paleozoic faults.Ancestral Rocky Mountain uplifts extend as far south as Chihuahua and west Texas (28° to 33°N, 102° to 109°W) and include the Florida-Moyotes, Placer de Guadalupe–Carrizalillo, Ojinaga–Tascotal and Hueco Mountain blocks, as well as the Diablo and Central Basin Platforms. All are cored with Laurentian Proterozoic crystalline basement rocks and host correlative Paleozoic stratigraphic successions. Pre-late Paleozoic deformational, thermal, and metamorphic histories are similar as well. Southern Ancestral Rocky Mountain structures terminate along a line that trends approximately N 40°E (present coordinates), a common orientation for Mesoproterozoic extensional structures throughout southern to central North America.Continuing Tien Shan intraplate deformation (Central Asia) has created an analogous array of uplifts and basins in response to the collision of India with Eurasia, beginning in late Miocene time when full coupling of the colliding plates had occurred. As in the Laurentia–Gondwana case, structures of similar magnitude and spacing to those in Eurasia have developed in the Indian plate. Within the present orogen two ancient suture zones have been reactivated—the early Paleozoic Terskey zone and the late Paleozoic Turkestan suture between the Siberian and East Gondwanan cratons. Inverted Proterozoic to early Paleozoic rift structures and passive-margin deposits are exposed north of the Terskey zone. In the Alay and Tarim complexes, Vendian to mid-Carboniferous passive-margin strata and the subjacent Proterozoic crystalline basement have been uplifted. Data on Tien Shan uplifts, basins, structural arrays, and deformation rates guide paleotectonic interpretations of ancient intraplate mountain belts. Similarly, exhumed deep crustal shear zones in the Ancestral Rockies offer insight into partitioning and reorientation of strain during contemporary intraplate deformation.     

Pan-African Alkali Granitoids from the Sør Rondane Mountains, East Antarctica

Alkali granitoids (500-550 Ma) representing a prominent Pan-African magmatic event are widely distributed in the Sør Rondane Mountains, Dronning Maud Land, East Antarctica. Geochemically, they are granitic to syenitic in composition and show an alkaline affinity of A-type granites. They are characterized by high K₂O+Na₂O (7-13 wt%) and K₂O/Na₂O (1-2), low to intermediate Mg#, wide ranges of SiO₂ (45-78 wt%), Sr (20-6500 ppm) and Ba (40-13000 ppm) and have Nb and Ti depletion in the primitive mantle normalized diagram. The granitoids are subdivided into Group I granites, Group II granites, Lunckeryggen Syenitic Complex and Mefjell Plutonic Complex. The Group I granites have higher Mg#, Sr/Ba, Sr/Y, (La/Yb)_N and LREE/HREE, lower A/CNK, SREE and initial ⁸⁷Sr/⁸⁷Sr ratios and lack Eu anomalies compared to those with negative Eu anomalies in the Group II granites. The syenitic rocks from the Mefjell Plutonic Complex are higher in alkali, Ga, Zr, Ba, and have lower Mg#, Rb, Sr, Nb, Y, F and LREE/HREE with positive Eu anomaly, whereas the granites from the Mefjell Plutonic Complex have high LREE/HREE ratios with negative Eu anomaly. The Lunckeryggen syenitic rocks have intermediate Mg#, higher K₂O, P₂O₅, TiO₂, Fe₂O₃/FeO, Ba, Sr/Y and LREE/HREE ratios with lack of Eu anomalies and are lower in Al₂O₃, Ga, Y, Nb and Rb/Sr ratios. Based on chemical characteristics combined with isotopic data, we suggest that the Lunckeryggen syenitic body and Group I granitic bodies may be derived from the mantle-derived hot basic magma by fractional crystallization with minor assimilation. We also suggest that the Group II granites may be derived from assimilation with crustal rocks to varing degrees and then fractional crystallization in higher crustal levels (ACF model). The Mefjell Plutonic Complex seems to be derived from a heterogenetic magma source compared with other granitoids from the Sør Rondane Mountains. The syenitic rocks in the Mefjell Plutonic complex have a unique source (iron-enriched) and have a chemical affinity with the charnockites in Gjelsvikjella and western Mühlig-Hofmannfjella, but not like the Yamato syenites in adjacent areas.     

赞皇变质窍隆黑云母^40Ar／^39Ar年代学研究及其对构造热事件的约束

太行山南段赞皇变质杂岩中黑云母给出了1827～1793Ma的~(40)Ar/~(39)Ar坪年龄,代表了变质基底在经历高温热扰动后冷却到300℃时的热事件年龄。结合华北克拉通变质岩的其他年代学资料,认为1800Ma士华北克拉通内经历了一次广泛而强烈的构造热伸展事件,致使克拉通基底岩石快速抬升到中上地壳,其冷却速率>6℃/Ma,隆升速率>200m/Ma。赞皇变质杂岩内苍岩寺、岗西-榆底-黑水河东和坡底-郝庄韧性剪切带内糜棱岩中黑云母分别给出了1689Ma、1633Ma和1645Ma的~(40)Ar/~(39)Ar坪年龄,代表了剪切带变形的主变形时代,这一年龄也为约束长城系的底界年龄提供了新的信息。结合已有的热年代学资料,推断华北克拉通内部赞皇变质地区中元古代的冷却速率约0.4℃/Ma,隆升速率为15m/Ma。由此也表明,自中元古代以来华北克拉通内部未受到后期构造热事件的强烈扰动,赞皇变质杂岩并非中生代变质核杂岩,而是早元古代变质穹隆。     

祁连山西段第四纪环境变迁研究

祁连山西段地处青藏高原西北缘，自更新世以来的环境变迁是青藏高原隆升过程的环境响应。笔者根据对CaCO3、古地磁、孢粉等资料的分析，初步划分了12个寒冷期和12个温暖期，并根据气候变迁的研究，认为青藏高原隆升至少有三次加速时期。     

From Flysch to Molasse——Sedimentary and Tectonic Evolution of Late Caledonian-Early Hercynian Foreland Basin in North Qilian Mountains

The Late Caledonian to Early Hercynian North Qilian orogenic belt in northwestern China is an elongate tectonic unit situated between the North China plate in the north and the Qaidam plate in the south. North Qiilan started in the latest Proterozoic to Cambrian as a rift basin an the southern mar-gin of North China, and evolved later to an archipelagic ocean and active continental margin during the Ordovician and a fardand basin from Silurian to the Early and Middle Devonian. The Early Silurian fly-sch and sulmmrine alluvial fan, the Middle to Late Silurian shallow marine to tidal flat deposits and the Early and Middle Devonian terrestrial.molasse are developed along the corridor Nansimn. The shallo-wing-upward succession from subabyssal flysch, shallow marine, tidal flat to terrestrial molasse and its gradually narrowed regional distribution demonstrate that the foreland basin experienced the transition from flysch stake to molasse stake during the Silurian and Devonian time.