石生藻类,地衣,苔藓与碳酸盐岩持水性及生态意义

对藻类,地衣,芭藓生物财溶校样品及相应岩石样品进行了室内蒸发失水,主动吸水试验,结果表明：与无生物覆盖的岩石相比,有藻类生物覆盖的岩石表面失水量,吸水量分别提高１８．８,１．６倍,蒸发失水,主动吸水的时间分别延长４８％,５７％,持水量提高１６．６倍,有地衣生物覆盖的岩石表面失水量,吸水量分别提高２．９,１９．１倍,蒸发失水,主动吸水的时间分别延长３１％,１１９％,持水量提高２．９倍;有苔藓生物覆盖     

Salinity reflux and dolomitization of southern Australian slope sediments: the importance of low carbonate saturation levels

Anomalously saline waters in Ocean Drilling Program Holes 1127, 1129, 1130, 1131 and 1132, which penetrate southern Australian slope sediments, and isotopic analyses of large benthic foraminifera from southern Australian continental shelf sediments, indicate that Pleistocene–Holocene meso‐haline salinity reflux is occurring along the southern Australian margin. Ongoing dolomite formation is observed in slope sediments associated with marine waters commonly exceeding 50‰ salinity. A well‐flushed zone at the top of all holes contains pore waters with normal marine trace element contents, alkalinities and pH values. Dolomite precipitation occurs directly below the well‐flushed zone in two phases. Phase 1 is a nucleation stage associated with waters of relatively low pH (ca 7) caused by oxidation of H₂S diffusing upward from below. This dolomite precipitates in sediments < 80 m below the sea floor and has δ¹³C values consistent with having formed from normal sea water (? 1‰ to + 1‰ Vienna Pee Dee Belemnite). The Sr content of Phase 1 dolomite indicates that precipitation can occur prior to substantial metastable carbonate dissolution (< 300 ppm in Holes 1129 and 1127). Dolomite nucleation is interpreted to occur because the system is undersaturated with respect to the less stable minerals aragonite and Mg‐calcite, which form more readily in normal ocean water. Phase 2 is a growth stage associated with the dissolution of metastable carbonate in the acidified sea water. Analysis of large dolomite rhombs demonstrates that at depths > 80 m below the sea floor, Phase 2 dolomite grows on dolomite cores precipitated during Phase 1. Phase 2 dolomite has δ¹³C values similar to those of the surrounding bulk carbonate and high Sr values relative to Phase 1 dolomite, consistent with having formed in waters affected by aragonite and calcite dissolution. The nucleation stage in this model (Phase 1) challenges the more commonly accepted paradigm that inhibition of dolomitization by sea water is overcome by effectively increasing the saturation state of dolomite in sea water.     

Carbonate deposition in a fluvial tufa system: processes and products (Corvino Valley – southern Italy)

In a multi‐scale approach to the study of the organic and mineral components in an active barrage‐type tufa system of southern Italy, neo‐formed deposits, in both natural depositional sites and on inorganic substrates placed in the stream for this study, were observed and compared through one year of monitoring. Dams and lobes representing the basic morpho‐facies of the deposits are composed of two depositional facies: vacuolar tufa (a mixture of phytoclastic and framestone tufa) and stromatolitic tufa (phytoherm boundstone tufa). Three petrographic components comprise both facies: micrite and microsparite, often forming peloidal to aphanitc, laminar and dendrolitic fabrics, and sparite, which occurs as isolated to coalescent fan‐shaped crystals forming botryoids or continuous crusts. All fabrics occurring in all depositional facies are organized into layers with a more or less well‐developed cyclicity, which has its best expression in stromatolitic lamination. The precipitation of all types of calcite (with Mg 1·0 to 3·2 mole % and Sr 0·5 to 0·8 mole %) takes place more or less constantly during all seasons, in spite of the low saturation state of the water (the saturation index range is 0·75 to 0·89) within the active depositional zone; the latter extends for a few hundred microns through the external surface of the deposit. The active depositional zone has a particular micro‐morphology composed of porous micro‐columns (50 to 150 μm in size), separated by interstitial channels. Mineral precipitation occurs upon both external surfaces and within internal cavities of the micro‐columns, while further point sites of precipitation occur suspended within the masses of cyanobacterial tufts. Sub‐spherical mineral units, ‘nano‐spheres’ (10 to 20 nm in diameter) are the basic biotic neo‐precipitate; they commonly form by replacing non‐living degrading organic matter and at point sites along the external surface of living cyanobacterial sheaths. Nano‐spheres agglutinate to form first rod‐shaped aggregates (100 to 200 nm) which then evolve into triads of fibres or polyhedral structures. Successively, both triads and polyhedral solids coalesce to form larger calcite crystals (mainly tetrahedrons tens of microns in size) that represent the fundamental bricks for the construction of the micro‐columns in the active depositional zone. Precipitation is attributed to the presence of a widespread biofilm that occurs in the active depositional zone; this is composed of a heterogeneous community comprising epilithic and endolithic filamentous cyanobacteria, green algae, unicellular prokaryotes, actinobacteria and fungi, with a variable amount of extracellular polymeric substances. No precipitation takes place where the biofilm is absent, indicating that the biological activities of the biofilm are crucial, with its living organisms and non‐living organic matter. Basic aggregates of neo‐precipitates do not form in association with any one particular type of organic matter substrate, but appear to be related to the seasonal temperature variation: polyhedral micro‐crystals mainly precipitate in the colder season, short triads in the intermediate seasons, and long triads in the warmest conditions. These three basic crystal aggregates have a petrographic counterpart, respectively, in the spar, microspar and micrite.     

Integrated biostratigraphy and carbon isotope stratigraphy of the Lower Cretaceous (Barremian to Albian) Adriatic-Dinaridic carbonate platform deposits in Istria, Croatia

The Adriatic-Dinaridic carbonate platform (ADCP) was one of the largest and relatively well preserved Mesozoic platforms in the Mediterranean region (central Tethys). The peninsula Istria, in the northwestern part of the ADCP, is built up predominantly of shallow-water carbonates of the Middle Jurassic (Dogger) to Eocene age and, to a lesser extent, of Paleogene clastic deposits (flysch and calcareous breccia). This study focuses on a Lower Cretaceous (Barremian to Albian) succession of strata at five localities in western Istria. Stratigraphic determinations are based on identification of nine microfossil assemblages (benthic foraminifera and calcareous algae Dasycladales) and on using their taxa as index fossils. The age of strata with these microfossil assemblages, however, is questionable. Most of the age uncertainties are associated with a regional emersion, which occurred on the ADCP during the Aptian or close to the Aptian-Albian transition. It is unclear what portions of the Upper Aptian and/or Lower Albian are missing along this unconformity. A stable isotope study was conducted on homogenous micritic matrix samples in an attempt to resolve some of these uncertainties. Variations in carbon isotope compositions proved useful for stratigraphic correlation between the examined successions of strata, for improving their age determination, and for relating them to other coeval successions that span an important time interval of major oceanographic changes and carbon-cycle perturbations associated with the Early Aptian oceanic anoxic event (OAE 1a).     

Biomarkers in the Molar Tooth （MT）-Bearing Limestones in the Jilin-Liaoning Area of China

The origin of Molar Tooth (MT) carbonates has been argued for more than 100 years, which are a kind of Proterozoic carbonates especially composed of microsparite with ptygmatically folded and sheet-like structures. Biomarkers detected in the microcalcsparite from the Wanlong and Xingmincun formations in the Jilin-Liaoning area showed there are abundant normal alkanes, isoprenoids, hopanes, steranes, alkylmethylcyclohexanes, and alkyleyclohexanes, indicating a diversity of biological source: long-chain isoprenoids, the major components of chlorophyll, such as C19, C20, a kind of major biomarkers synthesized early by isoprenoid monomers; hopanes a type of characteristic biomarkers from prokaryote, such as archaebacteria and cyanobacteria; sterane a biomarker for eukaryote; and two kinds of alkanes with C17, C18 as the main peaks representing aquatic bacteria and with C23, C24 as the main peaks representing fungi, respectively. Biomarker analysis showed that MT is the result of bacterial and algal activities, which is a kind of organisms between aerobic and anaerobic bacteria, reproducing well in normal or slightly saline sea water under weak oxidation-reduction conditions, resulting in rapid deposition of calcite as microsparite clue to some mechanisms.     

广西灌阳地区碳酸盐岩层滑断裂构造地球化学系统

灌阳地区碳酸盐岩中的层滑断裂构造地球化学系统具有典型的结构分带性、变形二重性和成分互补性。在这个系统中存在着Cu→Fe3 →V→Si→Al→Mn→Ba→Ni→Sr→Ag→Bi→Ga→In→Pb→Fe2 →Cr→Co→Zn→Mg→Ca→CO2的稳定性递减序列。影响构造地球化学分异的因素是原岩的性质、应力、温度和流体。构造地球化学作用的基本类型有：动力分异作用、压溶作用和氧化还原作用。层滑断裂带并非还原环境，碳质富集源自有机碳的氧化。Sr是高应力环境同构造重结晶方解石带的特征元素，Zn是低应力环境裂隙充填型方解石脉的特征元素。     

Larger Foraminiferal Biostratigraphy and Facies Analysis of the Oligocene–Miocene Asmari Formation in the Western Fars Sub-basin, Zagros Mountains, Iran

The Oligocene–Miocene carbonate record of the Zagros Mountains, known as the Asmari Formation, constitutes an important hydrocarbon reservoir in southern Iran. This marine carbonate succession, which developed under tropical conditions, is explored in terms of larger foraminiferal biostratigraphy, facies analysis and sequence stratigraphy in a new section at Papoon cropping out in the western Fars sub-basin, in the south-east of the Zagros belt. Facies analysis shows evidence of re-working and transport of skeletal components throughout the depositional system, interpreted here as a carbonate ramp. The foraminifera-based biozones identified include the Globigerina–Turborotalia cerroazulensis–Hantkenina Zone and Nummulites vascus–Nummulites fichteli Zone, both of Rupelian age, the Archaias asmaricus–Archaias hensoni–Miogypsinoides complanatus Zone of Chattian age and the ‘Indeterminate’ Zone of Aquitanian age. The vertical sedimentary evolution of the formation exhibits a progressive shallowing of the facies belts and thus the succession is interpreted as a high-rank low-order regressive systems tract. This long-lasting Rupelian–Aquitanian regressive event is in accordance with accepted global long-term eustatic curves. Accordingly, long-term eustatic trends would have been a factor controlling accommodation during the deposition of the Asmari Formation studied in the western Fars sub-basin.     

雄安新区牛东断裂带碳酸盐岩热储探测及其对地热勘探的启示

雄安新区在暂不考虑开采砂岩热储地热资源的前提下,探明碳酸盐岩热储东部边界断裂牛东断裂带的分布位置与地热资源品质,对新区地热资源开发利用规划的编制与整体能源利用布局均有着重要意义。以雄安新区高铁片区第一口碳酸盐岩热储勘探井D09孔的探测数据为依据,结合地震剖面解释成果,分析了牛东断裂带内碳酸盐岩热储的空间展布特征、储集层物理性质与单井产能参数,并简述其对地热勘探的指导意义。探测结果表明,牛东断裂带的碳酸盐岩热储主要为蓟县系雾迷山组含硅质的白云岩,分布在断裂西侧基岩宽缓背斜顶部,层状稳定,厚约2000m,顶板埋深1000~1200m,井口水温约70℃,单井水量约102m3/h。D09孔揭示,在距风化壳顶部678m的地层内共发育122个裂隙带,累计厚度达251.20m,裂隙发育率37%,平均孔隙度9.26%,裂隙发育率与平均孔隙度明显比断裂带外地热井高出50%。D09孔与牛东断裂带周缘地热井的地层地温梯度、地热水水化学特征、储集层导水系数等对比分析表明,垂直断距达7000m的牛东断裂带是一条导水导热的盆内隐伏型深断裂,其限定了雄安新区碳酸盐岩热储含水系统的东部边界,构成了西侧牛驼镇凸起的导水通道与东侧霸县凹陷油气运移的阻隔屏障,控制了牛驼镇凸起面积达1000km2的整装地热田的形成。     

Sinian-Cambrian Tectonic Framework in the Tarim Basin and its Influences on the Paleogeography of the Early CambrianEI北大核心CSCD

Due to strong remodification and sparse trace remnants, tectonic restoration is critical for the reconstructing of the paleography and basin-prototype in the multiple-cycles superimposed basin, which is also fundamental for the hydrocarbon exploration of the deep marine carbonate in the Tarim Basin. This study presents the tectonic framework of the transition phase from the Sinian to the Cambrian Period and its constrains on the paleography of the Cambrian in the Tarim Basin based on comprehensive analysis of new geochronology data, seismic data and regional tectonic data. The results showed that (1) there is a large regional unconformity between the Cambrian and Precambrian, suggesting a discontinuous deposition from the Sinian to the Cambrian that is contrary to the major view; (2) a broad flattened paleotopography formed before Cambrian Period, which is favorable for the wide epicontinental sea environment and a gentle homoclinal ramp platform development in the early Cambrian, and the residual basement low relief uplifts that influence the microfacies differentiation in the carbonate platform; (3) the Cambrian carbonate platform has been involved much into the marginal orogenic belts, and the proto-platform is probably of 200 km out of the present basin in S-N direction; (4) there is a weak extensional setting in the Cambrian-Early Ordovician rather than a strong rifting setting with a large aulacogen into the platform, in which a inter-platform shallow depression and stable ramp platform developed in the Cambrian; (5) there is not troughs, but rather low relief uplifts developed in the Early Cambrian in the southwestern Tarim Basin, and lack of large uplifts along the carbonate platform margins; (6) it is showed a broad architecture of platform-wide slope-ocean basin from the inner Tarim plate to its margin in the Cambrian Period. Considering the basin prototype, the restoration of the tectono-paleography in the early Cambrian in the Tarim Basin is distinct from those of the previously proposed. We propose that a gentle pattern with “two platforms and one inter-depression” in E-W striking other than multiple small platform constrained in the basin, and further subdivision of the western platform with inner platform low uplift and sag in N-S striking, which is possibly inherited from the basement architecture. On the outer of the united platform, there is probably broad gentle slope for transition to ocean basin. We therefore argue that tectonic restoration is crucial for reconstruction of the paleogeography and basin prototype, especially for basins experienced multiphase of tectonic cycles. © 2018, Science Press. All right reserved.     

全球碳酸锂贸易格局与供应危机传播研究

随着新能源产业的快速发展, 全球碳酸锂贸易量逐渐增长, 但其出口集中于少数国家, 这意味着全球碳酸锂供应存在一定的风险。为了深入了解全球碳酸锂贸易格局演变、供应危机传播路径及影响, 本文构建了2000—2021年全球碳酸锂贸易网络和级联失效模型, 概述了主要出口国贸易流向和贸易格局演变过程, 并模拟了不同供应危机来源的雪崩规模、传播路径及其影响。我们得到: (1)20多年来全球碳酸锂贸易集中度逐渐增加, 出口前三位国家保持稳定, 而主要进口大国变化明显, 贸易格局已由南美供应全球转变为南美供应东亚; (2)碳酸锂贸易供应危机的影响范围逐渐扩大, 间接传播逐渐占据主导地位; (3)智利供应危机对中日韩的影响程度逐渐扩大, 但对欧洲的影响时间最长; 阿根廷和中国的雪崩规模在上升、传播次数增加, 而美国则相反。本文将贸易格局演变与危机传播结合, 明确了全球碳酸锂主要贸易国智利、阿根廷、中国、德国等作为供应危机来源的影响程度及其传播路径。以上分析结果将有利于维护全球碳酸锂贸易稳定和主要贸易国采取应对策略缓解供应危机。