A Possible Long-tailed Bird with a Pygostyle from the Late Mesozoic Yixian Formation, Western Liaoning, China

An incomplete caudal vertebral series (IVPP V11309) from the Yixian Formation of late Mesozoic, Jianshangou area of Beipiao, western Liaoning Province, may represent a new bird. The tail is composed of at least 12 free caudal vertebrae and the most distal 5 caudal vertebrae co-ossified into a pygostyle. The pygostyle is plate-like and slightly curved dorsally. The anterior free caudals are amphiplatyan. The anterior caudal surfaces of the last three free caudals are concave, but their posterior articular surfaces are convex. The pygostyle is regarded as the first appeared flight apparatus during the evolutionary process from Archaeopteryx to neornithes. The pygostyle appeared in most early fossil birds and almost all the modern birds. Although their morphologies are different, they are basically formed by at least four last caudal vertebrae. The specimen V11309 is regarded as a bird rather than a non-avian theropod dinosaur based on the following characters: short caudal vertebrae, numerous pits present on the surfaces of the centra and, a foramen present between the basal part of the fused neural spines, which is similar to that of Struthio camelus. The discoveries of pygostyles from the therizinosauroids and oviraptorosaurs may provide strong evidence for supporting the origin of birds from small theropod dinosaurs. The structure of the pygostyle in specimen V11309 is different from those of Beipiaosaurus (Therizinosauroid) and Nomingia (oviraptorosaur). The most parsimonious interpretation is that these pygostyle-like structures are independently acquired by Beipiaosaurus and Nomingia during their evolutionary process.

Geochronology and Petrogenesis of Mesozoic Granitoids in the Geological Corridor of Western Liaoning Province, China

The geological corridor of Western Liaoning province is an area of length 100 km and width 20 km and located in the eastern segment of northern margin of North China Craton（NCC）,with the wide distribution of Mesozoic granitic magmatism.It is the ideal area to study the granitic petrogenesis,the nature of magma source and the tectonic attribute.In this paper,we do the systematic researchesaboutthepetrology,geochronology,geochemistry and Zircon Hf isotopic of granitic rocks.Based on the mentioned above,we have built the geochronological framework and have discussed the petrogenesis,the nature of magma source and the tectonic setting of granitic rocks.And according to the information about the crust-mantle interaction recorded in granitic rocks and the regional data,we also discuss the relationship between Mesozoic granitic magma activities and lithosphere thinning,destruction of Craton mechanism in the eastern segment of northern margin of NCC.The Mesozoic granitic magma activities in The geological corridor of Western Liaoning province are divided into four stages（Fig.1）:Late Triassic（230 Ma;28 Ma）,early-middle Jurassic（194 Ma;69 Ma）,Late Jurassic（161 Ma;55 Ma）and Early Cretaceous（139Ma;21 Ma）.The late Triassic granitic rocks are composed of adamellite,monzogranite and diorite.The samples have high Sr,Cr,Ni content and low Yb,Y content,and the sample have high Mg#and high ratio of Sr/Y and La/Yb.The characteristics of inhomogenous negative value ofεHf（t）(-6.40;0.19)in magmatic zircons and ancient crustal TDM2 values of 1.25 Ga;.67 Ga（Fig.2）,indicate that the Triassic granitic rocks were formed in a post-collisional extensional tectonic setting aftersubduction of Paleo-Asian Ocean and the subduction of Yangtze Craton,and they are the product of partial melting of ancient lower crust under the condition of the mantle-derived magma underplating,and geochemical features of the high Sr and low Y are inherited from the source of magma which is also enriched in Sr and depleted in Y.The geochemical features and assemblages of rocks formed during Jurassic-early Cretaceous are similar.The early-middle Jurassic granitic rocks are composed of syenogranite,monzogranite,quartz monzonite,granitic porphyry,granodiorite and quartz diorite.The late Jurassic granitic rocks are composed of monzogranite,granitic porphyry,and quartz diorite.The early Cretaceous granitic rocks are composed of monzogranite,quartz syenite,granitic porphyry,and quartz monzodiorite.The samples are characterized by the high SiO;content and total alkalis and are belonged to the high-K calc-alkaline series.And the characteristics of quasi-aluminous to weakly peraluminous（A/CNK<1.1,A/NK>1.0）and the negative relationship between P;O;and SiO;are similar to the characteristics of I-type granite.The samples are enriched in LREE contents and K,Pb and depleted in Nb,Ta,Ti and P.The characteristics of assemblage and geochemical features indicate the Jurassic-Cretaceous granitic rocks formed in the setting of active continental margin related to the subduction.The magmatic zircons of early-middle Jurassic granitic rocks have negativeεHf（t）(-16.60;4.15)and ancient crustal TDM2 values of 1.49 Ga;.28 Ga which indicates the primary magma is from the partial melting of ancient middle-lower crust（Fig.2）.These rocks formed in the setting of active continental margin of subduction of Paleo-Pacific plate.The magma source of granitic rocks is from partial melting of the ancient lower-middle curst caused by the underplating of mantle magma,which formed in the condition of fluid derived from the dehydration of subducted slab affected on the lithosphere mantle.The magmatic zircons of late Jurassic granitic rocks have negativeεHf（t）(-26.24;18.56)and ancient crustal TDM2 values of（2.39 Ga;.87 Ga）which indicates the primary magma is from the partial melting of ancient upper-middle crust（Fig.2）.And these rocks may be formed in the setting of active continental margin of intense subduction of Paleo-Pacific plate.In the intense subduction,the mantle magma is formed in the interaction of fluid derived from the dehydration of subducted slab with the lithosphere mantle,then further underplated the ancient middle-upper crust and make the ancient middle-upper curst partial melting.In this setting,the late Jurassic rocks are distributed widely in eastern North China.The samples in early Cretaceous have a wide range of values of Hf isotope:-24.92;20.88（139 Ma）,-4.72;6.22（130 Ma）,-17.30;11.56（125 Ma;21 Ma）,and the characteristics of Hf isotope indicate the source of earlyCretaceousmagma（middle-uppercrust,middle-lower crust or juvenile crust）is very complicated（Fig.2）.The early Cretaceous granitic rocks were formed in the lithosphere extensional environment when the Paleo-Pacific plate subducted/roll-backed quickly in the direction of NNW with high angle.The regional extension made the asthenosphere upwell and be unstable,and the magma of mantle was formed.Then wide mantle-crust interactions make the crust partial melt,as a result,the source of early Cretaceous igneous rocks which are distributed widely in eastern North China Craton.The participation of depleted mantle components in the process of Late Triassic rock formation in western Liaoning area indicate the time of the lithosphere thinning in the eastern segment of northern margin of NCC begin from the late Triassic（;30 Ma）.The double subduction of Paleo-Asian Ocean and Yangtze Craton in the early period is the reason of the lithosphere thinning.After the double subduction,the mantle-derived magma upwell and underplate the lithosphere mantle and lower crust in a post-collisional extensional tectonic setting.As a result,the lithosphere began to thin but the Craton destruction was not obviously in this period.The participation of depleted mantle components makes the continental crust slightly reforms and grows.The eastern segment of northern margin of NCC was in the setting of active continental margin in Jurassic,and the continuing dehydration and metasomatism of subduction slab changed the physical and chemical properties of the lithosphere mantle.The initial weak subduction in early-middle Jurassic makes the lithosphere become thin but no obvious destruction of Craton.And in this period,the continental crust reformed and grew slightly.As the subduction became stronger during late Jurassic,the thickness of lithosphere in eastern segment of northern margin of NCC become thinner and the destruction of Craton occurred locally and the continental crust reformed and grew to some extent.In early Cretaceous,the change of direction and angle of subduction of Paleo-Pacific led to the regional extension,which is the reason for massive mantle material upwelling and intense crust-mantle interaction.And the lithosphere thinning and destruction of Craton reached the peak.As a result,the effects of reconstruction and hyperplasia of continental crust are obviously.In our opinions,the underplating mechanism of mantle-derived magma occurred mainly in the initial stage（early Mesozoic）oflithosphere thinning,and the delamination of lithosphere mantle or lower crust coexisted while erosion action of mantle material occurred in the stage（late Mesozoic）of strong lithosphere thinning and destruction of Craton.

Early Cretaceous precious fossil-bearing beds in Weijialing—Yaolugou of Jianchang Basin,western Liaoning

The Jianchang Basin is one of the main localities of the precious fossils of Jehol Biota in western Liaoning.The fossil-bearing horizons are mainly in the Yixian-and Jiufotang formations.In the Weijialing--Yaolugou of southwest Jianchang Basin,many precious fossils have been found at Luojiagou Bed of the 2nd Member of the Yixian Formation and at Xidian Bed of the 1st member of the Jiufotang Formation.The geologic setting,sedimentary environment and paleogeography of the precious fossil-bearing beds were also studied.

Evolution, Migration, Controlling Factors and Forming Setting of Mesozoic Basins in Western Shandong

The distinctive topography in western Shandong province consists of several NW-WNW-trending mountain ranges and intervening basins. Basins, in which late-stage sediments to the south have progressively overlapped the earlier sediments and ＂basement＂ rocks of the hanging-wall block, are bounded by S-SW-dipping normal faults to the north. Basin analysis reveals the Jurassic-Cretaceous sedimentary rocks accumulated both within the area of crustal extension and during extensional deformation; they contain a record of a sequence of tectonic events during stretching and can be divided into four tectonic-sequence episodes. These basins were initially developed as early as ca. 200 Ma in the northern part of the study area, extending dominantly N-S from the Early Jurassic until the Late Cretaceous. Although with a brief hiatus due to changes in stress field, to keep uniform N-S extensional polarity in such a long time as 130 Ma requires a relatively stable tectonic controlling factor responsible for the NW- and E-W-extensional basins. The formation of the extensional basins is partly concurrent with regional magmatism, but preceded magmatism by 40 Ma. This precludes a genetic link between local magmatism and extension during the Mesozoic. Based on integrated studies of basins and deformation, we consider that the gravitational collapse of the early overthickened continental crust may be the main tectonic driver for the Mesozoic extensional basins. From the Early Jurassic, dramatic reduction in north-south horizontal compressive stress made the western Shandong deformation belt switch from a state of failure under shortening to one dominated by extension and the belt gravitationally collapsed and horizontally spread to the south until equilibrium was established; synchronously, the normal faults and basins were developed based on the model of simple-shear extensional deformation. This may be relative to the gravitational collapse of the Mesozoic plateau in eastern China.

辽西于寺盆地膨润土矿地质特征及控矿因素分析

于寺盆地为一中生代小型火山岩构造盆地,轴向北西西—南东东。盆地内膨润土资源量较为丰富,矿床、矿点众多,主要分布在盆地的南北两翼。总体上,蒙脱石含量呈现“北翼高南翼低”、矿石属性“浅部钙基深部钠基”的特点。矿床类型为火山碎屑岩—熔岩蚀变改造型膨润土矿床。构造样式、地层岩性、水化学条件、蚀变作用是膨润土矿床的主要控矿因素。

辽西地区中生代构造格局及其形成演化

在横穿辽西地区构造变形剖面及重点区段的详细构造解析的基础上 ,结合构造变形、沉积组合、岩浆岩特征及同位素年代学等资料 ,对辽西地区中生代以来的总体构造格局进行了厘定 ,认为辽西地区中生代主要构造格局由印支期的东西向褶皱 -逆冲构造、早燕山期的北东向叠瓦状逆冲推覆构造、晚燕山期早期的北东向“盆 -岭”构造。

辽西中生代晚期岩石圈地幔的性质:来自玄武岩和地幔捕虏体的证据

辽西中生代玄武岩中幔源橄榄岩捕虏体的岩石学、矿物学和地球化学研究表明 ,中生代岩石圈地幔是由古老富集型的岩石圈地幔和新增生的岩石圈地幔所组成。前者以角闪尖晶二辉橄榄岩为代表 ,它经历了富钠质的地幔交代作用。橄榄岩类捕虏体富含轻稀土元素 ,并具有较高的w(87Sr) /w(86Sr)比值 ;后者以二辉石岩为代表 ,具典型堆积结构 ,与本区尖晶石二辉橄榄岩相比 ,具有较高的稀土元素丰度。在矿物成分和稀土元素丰度上 ,本区辉石岩捕虏体类似于中国东部新生代玄武岩中幔源辉石岩捕虏体 。

松辽盆地外围油气新区中生代地层研究新进展

通过对松辽盆地外围西部中生代重点盆地的调查分析,重新划分了龙江盆地的中生代地层,特别是重新解释了甘河组的含义;解体了突泉盆地的付家洼子组,将其分别划归为付家洼子组、满克头鄂博组、玛尼吐组;重新划分了扎鲁特盆地的火山岩地层,根据同位素年龄测试结果,将一部分划归古生界大石寨组的火山岩地质体分别划归中生界塔木兰沟组、玛尼吐组;建立了松辽盆地外围西部中生代重点盆地,包括龙江盆地、突泉盆地、扎鲁特盆地和乌兰盖盆地中生代地层的对比关系。

辽西中生代粗面玄武岩中地幔和下地壳捕虏体的发现及其地质意义

辽西中生代粗面玄武岩的K-Ar同位素年龄为84.76±1.67Ma,其中含有丰富的超镁铁质岩和深部壳源捕虏体,主要有角闪尖晶二辉橄榄岩、尖晶石二辉橄榄岩、二辉橄榄岩、含斜长石的角闪二辉石岩、二辉麻粒岩和辉石斜长片麻岩等。包体的组构及矿物化学研究表明超镁质岩捕虏体来源于上地幔,麻粒岩和片麻岩则为深部壳源捕虏体。该类包体的发现对中国东部中生代上地幔和下地壳的研究具有重要意义。

柴达木盆地西部中生界原型盆地及其演化

柴达木中生界盆地形成时间及其盆地原型研究存在很大争议,主要原因在于对盆地内有无三叠系陆相沉积及其与上覆下侏罗统地层接触关系和中生界原型盆地形成的构造背景等问题认识不清。区域地质调查在盆地西部月牙山北发现中、上三叠统陆相地层与上覆下侏罗统地层整合接触,在此基础上,结合地表露头、古流分析及地震解释资料研究认为:柴达木中生界盆地起始于中三叠世。中生代在古阿拉巴斯套山与古昆仑山间发育一个大的近东西向展布的活动型山间盆地,盆地经历了中—晚三叠世、早—中侏罗世和晚侏罗世—白垩纪三个演化阶段,分别对应发育了中—晚三叠世坳陷型盆地、早—中侏罗世断陷型盆地和晚侏罗世—白垩纪坳陷型盆地三种原型盆地类型。中—晚三叠世盆地分布比较局限,沉积以氧化环境下的红色碎屑岩建造为主,不具生烃能力;早—中侏罗世盆地范围扩大,沉积物以暗色含煤建造为主,主要分布于现今的阿尔金山地区及其山前地带,沉积中心在阿尔金山地区。晚侏罗世—白垩纪阿尔金山快速隆升,成为主要物源区,开始分割塔里木和柴达木盆地沉积,沉积物为红色磨拉石建造。该研究对于准确评价柴达木盆地生烃潜力及合理进行勘探部署具有重要意义。

鄂尔多斯盆地西缘北段中生代构造演化

鄂尔多斯盆地西缘构造带处于独特的大地构造位置,具有复杂的构造特征。长期以来,不同学者对北段构造特征和属性、构造演化和形成机制等开展了大量的研究工作,观点不尽相同。本文在系统研究西缘北段构造带几何学的基础上,通过沉降史分析与岩石类型分析等方法,对其运动学进行解释。研究认为西缘构造带的冲断活动以及盆地的沉降与青藏高原地体增生事件以及伊泽奈琦板块的俯冲关系非常密切。盆地西缘南北向逆冲推覆带在晚三叠世——白垩纪时期内构造基本定型,相应的西缘发育陆内前陆盆地,并发育多套同构造的粗碎屑的沉积。

晚中生代中国东部高原北界探讨

中国东部高原的界线主要是依据埃达克岩的分布确定的。现已知道,高原最北部的中生代埃达克岩主要分布在辽西-冀北-内蒙古南部一带。该区可靠的埃达克岩仅发育在晚侏罗世或早白垩世的早期(如132±5Ma的安家营子花岗岩)。现有资料表明,大致以赤峰-开原断裂为界,埃达克岩分布于其南,其北为非埃达克岩分布区,暗示中国东部高原的北界大体沿赤峰-开原一带分布,代表的是侏罗纪时期的高原边界。辽西义县组地层位于高原范围内,众所周知,义县组第2段(124～127Ma)是热河生物群集中发育的阶段,说明当时的气候温湿、植物繁茂、水草丰盛、地势低洼、湖沼发育,不大可能为动植物贫瘠的高寒山区。义县组火山岩的研究表明,早白垩世(135～120Ma)的义县组主要由玄武岩和赞岐岩(高镁安山岩)组成,并非埃达克岩。因此,至少在127Ma左右,在热河生物群分布的地区,已经不存在高原了,高原的界线南移了,可能移到热河生物群发育区之南的宣化-滦平-锦州一线,其南仍然处于高原环境。高原抬升的直接结果是导致同时代沉积物的缺少,或有一些沉积盆地发育,但是厚度很薄。在中-晚侏罗世时,高原上的沉积盆地很少,且缺失上白垩统地层,总体上反映高原处于抬升状态。高原北缘和西北缘早白垩世冰筏和冰川泥石流沉积的出现,暗示高原的北缘可能具有相当的高度,可能类似现今的喜马拉雅山。该区中生代构造特征表明,该区侏罗纪和早白垩世的构造特点有着巨大的差异:侏罗纪,尤其是晚侏罗世末期以南北向的挤压构造为主,而早白垩世中期以后演变为以伸展构造为特征,古地理古环境明显改变。研究表明,中国东部中生代埃达克岩形成的时限大致限定了高原的起始和消亡时间。据最近几年发表的资料,埃达克岩的时代大体限定在170～120Ma之间,表明中国东部高原在170Ma之前开始出现,大约在晚侏罗世达到顶峰,在早白垩世中期(120Ma)以后消失。辽西-冀北的构造、地层和火山岩资料表明,侏罗纪时期本区属于挤压构造环境,高原处于抬升状态;至早白垩世(大体从127Ma左右开始)转变为伸展构造背景,含有丰富热河生物群的阜新-义县-朝阳-丰宁一带已经沉陷,暗示中国东部高原的垮塌可能先从北缘开始,至120Ma左右,高原才整体垮塌。

燕山造山带东段——辽西地区薄皮逆冲推覆构造

辽西地区为华北北缘中生代燕山造山带东延部分。地表地质调查和新的地震剖面资料的构造解释表明辽西地区逆冲推覆构造系为大型薄皮构造组成的楔形体,主要由凌源—北票逆掩断层、牛营子—郭家店逆掩断层、汤神庙逆掩断层和建昌—朝阳逆掩断层,以及在这些逆掩断层上盘发育的大型推覆体组成。逆冲构造的扩展方式为背驮式,逆冲指向南东,定型时代为早白垩世中期,即早白垩世义县组火山碎屑岩(110Ma)和早白垩世九佛堂组之间。中侏罗世—早白垩世中期形成的辽西地区道冲推覆构造系既与西伯利亚板块与华北板块之间蒙古—鄂霍茨克大洋最终闭合碰撞有关,同时也与古太平洋板块向西俯冲在东亚大陆之下有关。

柴达木盆地西部中生界原型盆地恢复

勘探实践表明,对柴达木盆地西部中生界原型盆地认识不够,是导致该区侏罗系油气勘探难以取得重大突破的主要原因。以古流分析为主要手段,结合地表露头及地震解释资料研究认为,中生界在古阿拉巴斯套山与古昆仑山间发育一个大的近EW向展布的内陆山间坳陷(古泛茫崖坳陷)。坳陷演化可分为早—中侏罗世和晚侏罗世—白垩纪两个阶段,分别对应发育了伸展断陷和挤压坳陷两种原型盆地类型。早、中侏罗世,阿尔金山尚未隆升,为主要沉积区。沉积环境比较动荡,沉积物以暗色含煤建造为主。沉积中心在现今的阿尔金山区,坳陷西北部边界越过阿尔金山区与塔东南地区相通;东北部边界位于阿拉巴斯套山前;南部边界在煤沟—采石岭—黑石山—月牙山一线。晚侏罗世—白垩纪,阿尔金山快速隆升为物源区,开始分割塔东南和柴达木盆地西部沉积。坳陷沉积物以干旱气候下的红色粗碎屑岩建造为主,沉积、沉降中心由阿尔金山区向盆地内部发生迁移,南部边界已迁移至阿拉尔—红柳泉—红沟子—月3井一带。该研究对柴达木盆地资源潜力评价及勘探部署具有重要意义。

柴西阿尔金山南缘中生界古流特征

柴达木盆地西部（柴西）的阿尔金山南缘自三叠系到白垩系发育了一套陆源碎屑岩,厚度可达3～4 km,露头条件非常好。其中,中、上三叠统及中、下侏罗统的陆源碎屑岩中发育了一些指示古流的沉积构造,主要有板状交错层理、槽状交错层理、爬升层理、槽模、炭化植物茎干及砾石。这些沉积构造指示柴西中生代古流格局比较复杂：在月牙山一带,中生代古流自北东流向南西,表明其物源区在北东方向,极有可能是以阿拉巴斯套为主体的古阿尔金山；在犬牙沟与采石岭一带,中生代的古流主要来自于南东方向和北东方向。前者可能与昆仑山和芒崖坳陷腹地的古隆起有关；后者可能与中部的砾石梁一带在中生代某些时期隆升形成＂陆桥＂而接通了来自北东方向阿拉巴斯套的水系有关。在砾石梁一带,中生代的古流格局则非常紊乱,表明其可能具有多个物源区。在阿拉巴斯套与昆仑山之间中生代发育了一个大的沉积坳陷（古泛芒崖坳陷）,这个坳陷呈近东西向,坳陷中心在砾石梁与月牙山南侧一带。

辽西晚中生代热河生物群中首次发现具胚胎的软壳蛋化石

本文详细记述了辽宁省锦州市义县晚中生代热河生物群中两类爬行动物的蛋化石 ,其中离龙类蛋化石发现于早白垩世九佛堂组上部 ,翼龙类蛋化石发现于早白垩世义县组上部的金刚山层。经研究 ,离龙类蛋化石不仅含有胚胎 ,而且为软壳蛋。翼龙类蛋化石没有显示硬壳结构 ,很可能同样为软壳蛋。这些蛋化石的发现对于我们了解这两类爬行动物的生殖方式和发育演化历史将具有重要科学意义。

川西两期前陆盆地南北两段构造演化的地球物理特征

区域构造演化研究结果表明 ,川西前陆盆地经历了早中生代和晚新生代两期前陆盆地演化过程。无论是前陆盆地的发育程度还是前陆变形特征及前渊带沉积作用 ,盆地的南、北两段都存在明显的差异。根据川西地区及邻区的重磁场特征 ,获得了川西地区基底性质及主要断裂带分布的研究成果。德阳—绵阳一带刚性基底对新生代变形由南向北的传播起了阻挡作用 ,奠定了新生代变形南强北弱的格局。同时 ,一系列北西向走滑断裂带的存在进一步削弱了新生代变形作用。基底性质的差异和北西向走滑断裂带的存在是造成川西前陆盆地南、北两段差异的主要制约因素 ,直接造成了南、北两段新生代变形的差异。

辽西阜新中生代玄武岩中深源捕虏体的岩石学和矿物化学研究

辽西阜新中生代碱性玄武岩的Ｋ－Ａｒ同位素年龄为８４．７６±１．６７Ｍａ， 其中含有丰富的深源岩石捕虏体， 包括角闪尖晶二辉橄榄岩、尖晶石二辉橄榄岩、含长角闪二辉石岩、二辉麻粒岩和辉石斜长片麻岩等。与新生代玄武岩中的同类捕虏体相比， 橄榄岩类捕虏体中橄榄石的成分相似 （Ｆｏ＝ ８６～９１）， 透辉石具有富Ａｌ、贫Ｃｒ 和Ｃａ 的特点， 尖晶石的成分以ＭｇＡｌ２ Ｏ４ 为主， 有的橄榄岩捕虏体中含少量韭闪石。二辉麻粒岩捕虏体中的斜方辉石为紫苏辉石， 单斜辉石为普通辉石， 斜长石属于更长石。橄榄岩类捕虏体的平衡温度为１０１２．６℃～１２７２．１℃； 压力为１．８２５～２．９３５ＧＰａ， 二辉麻粒岩和片麻岩的平衡温度为８９２℃～１１５７℃。该类深源岩石捕虏体的发现对中国东部中生代上地幔和下地壳的研究均具有重要意义。

辽西中生代沉积岩稀土、微量元素地球化学特征及其构造背景

辽西地区在中生代时期经历了三次火山—沉积旋回,形成的沉积岩中蕴含大量的地壳演化信息。采用电感耦合等离子体质谱(ICP-MS)测定了该区中生代沉积岩的稀土、微量元素含量,应用微量元素La—Sc—Th、Th—Co—Zr/10沉积构造背景判别图解对区域构造背景进行了探讨。结果表明:1中生代沉积岩稀土元素含量较高,具有后太古宙沉积岩特征;2三叠纪不同时期沉积岩具有相同的微量元素曲线分布型式,侏罗纪、早白垩世期间沉积岩的稀土元素曲线相对分散,分别具有两种、三种微量元素分布曲线型式,反映沉积物源的变化和活化的沉积构造背景;3中生代时期,构造环境复杂,大陆岛弧型为主,三叠纪—侏罗纪期间处于转型期,兼有稳定的被动大陆边缘型特征,早白垩世兼有活动大陆边缘型特征,构造环境更为活化。

东海陆架盆地西部坳陷带中生界分布特征及其有利区探讨

对东海陆架盆地西部坳陷带中生界分布特征及其油气勘探方向的研究认为:研究区中生界分布广、厚度大,主要沉积在南部地区,最大厚度超过6 000 m,除凹陷内有分布外,隆起区也有分布。白垩系主要发育在长江凹陷、海礁低凸起、瓯江凹陷、闽江凹陷和台北低凸起地区;侏罗系主要发育在闽江凹陷。闽江凹陷的中生界厚度大,烃源岩条件好,局部构造圈闭发育,既有区域性盖层又有局部盖层,生储盖条件优越。因此,闽江凹陷是东海陆架盆地西部坳陷带油气勘探前景最好的区域。