湘黔桂相邻区新元古代820～635Ma时期裂谷盆地充填序列与地层格架

湘黔桂相邻区发育一套序列完整、界面清楚的武陵造山运动不整合面之上至震旦纪(820~635 Ma)时期的裂谷盆地沉积地层。通过详细的区域岩石地层划分与对比,结合年代学研究成果,显示其时空展布格局完整,充填序列连续,划分标志清楚,完全可以划分对比。在此基础上建立了其地层格架,为扬子古大陆周缘新元古代820~635 Ma时期地层划分对比研究提供了详实的资料,亦为中国前寒武系新元古代地层划分对比及国际新元古代研究提供了新的资料成果。     

Late Cenozoic Deformation Sequence of a Thrust System along the Eastern Margin of Pamir, Northwest China

A thrust belt formed in the basin along the eastern margin of Pamir. The thrust belt is about 50 km wide, extends about 200 km, and includes three compressive structures from south to north: the blind Qipan structural wedge and Qimugen structural wedge, and the exposed Yengisar anticline. The thrust belt displays a right-stepping en echelon pattern. The Qipan structural wedge dies out northward to the west of the Qimugen structural wedge, and the Qimugen structural wedge dies out northward to the west of the Yengisar anticline. Detailed analysis of seismic reflection profiles of the western Tarim Basin reveal that fan-shaped growth strata were deposited in the shallow part of the thrust belt, recording the deformation sequence of the thrust belt. The depth of the Cenozoic growth strata decreases from south to north. The growth strata of the Qipan structural wedge is located in the middle-lower section of the Pliocene Artux Formation (N2a), the growth strata of the Qimugen structural wedge is close to the bottom of the Pleistocene Xiyu Formation (Q1x), and the growth strata of the Yengisar anticline is located in the middle section of the Xiyu Formation (Q1x). Combined with magnetostratigraphic studies in the western Tarim basin, it can be preliminarily inferred that the deformation sequence of the thrust belt along the eastern margin of Pamir is progressively younger northward. The geometry and kinematic evolution of the thrust belt in the eastern margin of Pamir can be compared with previous analogue modeling experiments of transpressional deformation, suggesting that the thrust belt was formed in a transpressional tectonic setting.     

内蒙古大梁道班地区叠加褶皱构造分析

内蒙古大梁道班地区位于二连-贺根山缝合带和西拉木伦断裂带之间,区内广泛发育大面积浅变质岩和火山岩。该地区横跨叠加褶皱较为典型,通过1:5万区域地质调查和研究横跨叠加褶皱的几何学、运动学特征,并对其形态、组合关系以及产状要素等进行半定量分析,大量统计与不同期次褶皱相配置的线理和面理数据,利用赤平投影,厘定出本区的三期叠加褶皱变形,同时建立本区的构造变形序列。认为第一期褶皱以区域规模的大型紧闭平卧褶皱为特征;第二期褶皱是在第一期褶皱的基础上发生的横跨叠加褶皱;第三期褶皱是以第二期褶皱轴面劈理和面理在走向上的蛇形弯曲为标志形成的宽缓直立褶皱。     

细胞色素b基因序列与7种石首鱼类的系统进化

通过比较一段381bp细胞色素b基因序列，分析了石首鱼科7种石首鱼的系统发育关系．该序列有51个单变异多态位点、128个简约信息多态位点，对应的氨基酸序列有41个氨基酸变异位点．根据Kimura 2参数构建的邻接树(NJ tree)和最大简约树(MP tree)都显示同样的结果：7种石首鱼类构成一个单系群．皮氏叫姑鱼位于单系群的基部，且与其他石首鱼分离时间很早；大黄鱼和棘头梅童鱼亲缘关系最近。并与钩牙皇石首鱼和波纹短须石首鱼构成姐妹群．黄姑鱼和鱿鱼也接近树的基部．     

潮坪层序的粒度特征与沉积相划分--以杭州湾庵东浅滩为例

现代潮滩依据多年平均潮位线划分高、中、低潮滩，这对于古代潮坪沉积相研究无实际意义。本文尝试用潮坪层序粒度参数剖面来划分沉积相。潮坪沉积物以粉砂为主，但敏感地反映沉积动力变化的却是粗、细尾部分。因此，在沉积相划分时主要依据粘土、砂含量及平均粒径的变化特征。分选系数是一重要依据，但要考虑絮凝沉积的影响。偏态和峰态变幅小、较复杂，在相划分中只具参考价值。利用粒度参数剖面进行潮坪沉积相划分可广泛应用于古代潮坪层序研究，而且根据中潮坪沉积厚度(x)与平均潮差(y)存在的显著性相关关系：y=1．8314x 157．31(单位cm)，推算古潮差。     

The inventory and chemical characterization of dissolved proteins in oceanic waters

One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high resolution two-dimensional electrophoresis (2-DE) were applied to separate protein molecules in dissolved organic matter (DOM) from oceanic waters. Results were: (1) The 2-DE distinguished a total of 412 protein spots in 10 samples from five water columns over the Pacific, although fewer than 30 proteins were resolved as bands from the identical samples by SDS-PAGE. (2) Major and ubiquitous protein bands (34 and 39 kDa proteins) on the SDS-PAGE gel were resolved into horizontally spread arrays (trains) of spots on the 2-DE gels, indicating that these bands were a mixture of protein species that have the same molecular weight (MW) but different isoelectric points (pIs). (3) Proteins that exhibited such electrophoretic patterns on the 2-DE gels were glycosylated with variable linkages between the sugar and polypeptide chains. (4) N-terminal amino-acid sequencing demonstrated that individual spots within each train of spots had identical N-terminal amino-acid sequences.The N-terminal amino-acid sequences of the 39 and 34 kDa glycoprotein spots in samples collected at different sites were also identical. Protein isoforms with the same amino-acid sequence but different glycosylation profiles, termed glycoforms, were often observed on the 2-DE gel. Thirty-one and 24 spots on the 2-DE gels were glycoforms of two glycoproteins with MWs of 39 and 34 kDa, respectively; they were one protein species. The glycoforms of the 39 kDa protein were identified as a low molecular weight alkaline phosphatase (L-AP) of Pseudomonas aeruginosa PAO1 by a homology search through five amino-acid sequence databases. The present and earlier work indicates that all identified source organisms of dissolved proteins belong to the Pseudomonas group. We propose the hypothesis that proteins associated with membrane vesicles liberated from a minor member of the bacterioplankton assemblage, the marine Pseudomonas group, are one of the important sources of dissolved proteins in oceanic waters. This hypothesis may apply to the source pathway and survival not only of proteins and also to the universally occurring bacterial peptidoglycan and lipopolysaccharide components in DOM.     

坛紫菜藻红蛋白α,β亚基基因的克隆和序列分析

藻胆蛋白(Phycobiliprotein,PBP)是原核藻类和真核藻类进行光合作用的捕光色素蛋白,占藻体干重的2%左右,主要分为3类:藻红蛋白(phycoer-ythrin,PE)、藻蓝蛋白(phycocyanin,PC)和别藻蓝蛋白(allophycocyanin,APC)[1].藻胆蛋白一般由α亚基和β亚基组成,部分藻胆蛋白中还存在γ亚基.一般由α和β亚基形成稳定的单体(αβ),再由单体聚合为多聚体(αβ)_n.从蓝藻和红藻中分离的藻胆蛋白为三聚体(αβ)₃或六聚体(αβ)₆[2].     

Seismic and sequence stratigraphy of the central western continental margin of India: late-Quaternary evolution

Seismic and sequence stratigraphic architecture of the central western continental margin of India (between Coondapur and south of Mangalore) has been investigated with shallow seismic data. Seismic stratigraphic analysis defined nine seismic units, that are configured in a major type-1 depositional sequence possibly related to fourth-order eustatic sea-level changes, comprising regressive, lowstand, transgressive and highstand systems tracts. The late-Quaternary evolution of the continental margin took place under the influence of an asymmetric relative fourth-order sea-level cycle punctuated by higher frequency cycles. These cycles of minor order were characterised by rapid sea-level rises and gradual sea-level falls that generated depositional sequences spanning different time scales. During the regressive periods, dipping strata were developed, while erosional surfaces and incised valleys were formed during the lowstands of sea level. Terraces, v-shaped depressions, lagoon-like structures observed on the outer continental shelf are the result of the transgressive period. In the study area we have recognised a complex erosional surface that records a long time span during the relative sea-level fall (regressive period) and the following sea-level lowstand and has been reworked during the last transgression. We also infer that sedimentation processes changed from siliciclastic sedimentation to carbonate sedimentation and again to siliciclastic sedimentation, marking an important phase in the late-Quaternary evolution of the western continental shelf of India. We attribute this to an abrupt climate change at the end of the oxygen isotope stage 2, between the Last Glacial Maximum and the Bølling-Allerod event (14?000 yr BP). This sensitive climate change (warming) favoured the formation of reefs at various depths on the shelf, besides the development of Fifty Fathom Flat, a carbonate platform on the outer shelf off Bombay developed prior to 8300 yr BP. The highstand systems tracts were deposited after the sea level reached its present position.     

Tectonic significance of syn-rift sediment packages across the Gabon-Cabinda continental margin

The tectonic development of a continental margin is recorded in the stratigraphic successions preserved along and across the margin in terms of stratal relationships (e.g., onlap, downlap, truncation), lithofacies, biostratigraphy, and paleo-water depths. By using these observations coupled to a kinematic and flexural model for the deformation of the lithosphere, we have elucidated the tectonic significance of the preserved stratigraphy that comprises the Gabon-Cabinda margin of west Africa. Two hinge zones, an Eastern and Atlantic, formed along the Gabon-Cabinda margin in response to three discrete extensional events occuring from Berriasian to Aptian time. The Eastern hinge zone demarcates the eastern limit of a broadly distributed Berriasian extension that resulted in the formation of deep anoxic, lacustrine systems as evidenced by the silts and shales of the Sialivakou and lower Djeno Formations and the regressive packages of the upper Djeno Formation. Approximately 1.5 to 2 km of asymmetric footwall uplift was induced across the Eastern hinge zone in response to the mechanical unloading of the lithosphere during this first phase of rifting. In contrast, the Atlantic hinge, located approximately 90 km west of the Eastern hinge, marks the eastern limit of a second phase of extension that began in the Hauterivian. Footwall uplift and rotation exposed earlier syn-rift and pre-rift sediments to at least wavebase causing varying amounts of erosional truncation across the Atlantic hinge zone along much of the Gabon-Cabinda margins. We interpret the thickness variations of reworked clastic sediment of this age (e.g. the Melania Formation) between the hinge zones as indicative of variations in the degree of uplift and erosional truncation of the Atlantic hinge. For example, the absence of Melania Formation across the Congo margin implies that uplift of the Atlantic hinge was relatively minor compared to that across the Cabinda and Gabon margins, the latter being characterized by significant thicknesses of Melania Formation (or equivalent). Material eroded from the Cabinda and Gabon Atlantic hinge zone may in part account for the thick wedge of sediment deposited seaward of the Gabon-Cabinda Atlantic hinge (the Erva Formation). Our modelling suggests that this wedge of reworked elastics represents deposition by along-axis gravity flows within a deep water (≈2 km) environment. A third and final phase of extension in the late Barremian-early Aptian was responsible for breaching the continental lithosphere to form the ocean/continent boundary and thus the installation of open marine conditions. Elsewhere, the environments will tend to be marginal marine to brackish, depending on the efficiency of the Atlantic hinge zone to act as a barrier to marine enchroachment. This third rift phase reactivated both the Eastern and Atlantic hinge0zones thereby creating accomodation for the Marnes Noires Formation (and equivalent) source rock deposition between the hinges and the Falcão source rock equivalent seaward of the Atlantic hinge. Two possible scenarios exist for the lateral distribution of the Marnes Noires Formation. If the reactivated rift flank topography across the Atlantic hinge was significant, then sedimentation would be restricted between the hinge zones within discrete lacustrine settings (e.g., Congo margin). Alternatively, if hinge zone uplift was relatively minor, then a coral-rimmed archipelago may have developed parallel to the margin with restricted communication across the Atlantic hinge zone (e.g., Cabinda margin). In this latter scenario, dilution of the Marnes Noires source rocks by terrigenous input from the eroding Atlantic hinge zone should be relatively minor thereby enhancing source rock quality. Furthermore, potential marine upwelling outboard of the Atlantic hinge zone is likely the cause for the production and accumulation of organic-rich material associated with the Falcão source rock of the Kwanza basin. By late Aptian time, the remaining accomodation between the hinge zones was partially filled by across- and along-axis prograding deltaic systems of the Argilles Vertes and Tchibota Formations. The progradation and interaction of the Argilles Vertes depositional lobes resulted in the formation of residual paleo-relief. Subsequent marine incursions and flooding of this paleo-relief led to the development of basal conglomerates (the Chela ‘lag’ unconformity) grading upward into fine-grained sands and evaporites. Consequently, an inverse relationship should exist betweeb evaporite thickness (in particular, the lower members) and the thickness of the underlying Argilles Vertes and Tchibota Formations. Variations in Loeme evaporite thickness is a consequence of stratigraphic and structural control with salt instability influencing local variability.Our modelling suggests the occurrence of two distinct evaporite sequences on the Congo margin, an earlier evaporite deposited seaward (west) of the Atlantic hinge during the second and third rift phases and the late Aptian Loeme Formation deposited between the hinge zones. An evaporite sequence seaward of the Atlantic hinge is inferred on the basis of extensive diapirs and salt tectonic structures observed in seismic data. In order to match the distribution and thickness of the observed post-salt stratigraphy across the basin, however, we require large paleowater depths west of the Atlantic hinge during the later Aptian. The existence of large paleowater depths precludes the formation of thick evaporite sequences within the outer basin. Consequently, we propose that the evaporites seaward of the Atlantic hinge were formed during the syn-rift development of the margin and are not contemporaneous with the post-rift Loeme salts deposited between the hinge zones. This double salt hypothesis is consistent with observations from the conjugate Brazilian margin.     

Marine seismics with a pulsed combustion source and Pseudo Noise codes

There has been a long-standing debate concerning how dangerous seismic surveys are with respect to marine life. Marine seismic work today is dominated by airgun technology, where high energy is generated by a release of compressed air into the water. The objective of the “Time coded impulse seismic technique” project is to examine whether a new low energy acoustic source can be used for seismic purposes. If the method turns out to be successful, the low output energy and continuous operation will make the source suitable in environmental sensitive areas. The Low level Acoustic Combustion Source (LACS) is a petrol driven pulsed underwater acoustic source. It operates at a few meters depth, and each shot can be digitally controlled from the surface by a computer located in the mother vessel. A presentation of the recorded LACS signal characteristics, the modulation, the Pseudo Noise coding/decoding principles and field test results, is given. The importance of using an optimized code with fine resolution and of using the near field recording as a correlator sequence is demonstrated. Clear correlation peaks could then be seen from the bottom and sub bottom reflectors.