Growing season evapotranspiration in boreal fens in the Athabasca Oil Sands Region: Variability and environmental controls     

Olena Volik  Eric Kessel  Adam Green  Richard Petrone  Jonathan Price 《水文研究》2021,35(2):e14020

Current efforts to assess changes to the wetland hydrology caused by growing anthropogenic pressures in the Athabasca Oil Sands Region (AOSR) require well-founded spatial and temporal estimates of actual evapotranspiration (ET), which is the dominant component of the water budget in this region. This study assessed growing season (May–September) and peak growing season (July) ET variability at a treed moderate-rich fen and treed poor fen (in 2013–2018), open poor fen (in 2011–2014), and saline fen (in 2015–2018) using eddy covariance technique and a set of complementary environmental data. Seasonal fluctuations in ET were positively related to net radiation, air temperature and vapour pressure deficit and followed trends typical for the Boreal Plains (BP) and AOSR with highest rates in June–July. However, no strong effect of water table position on ET was found. Strong surface control on ET is evident from lower ET values than potential evapotranspiration (PET); the lowest ET/PET was observed at saline fen, followed by open fen, moderately treed fen, and heavily treed fen, suggesting a strong influence of vegetation on water loss. In most years PET exceeded precipitation (P), and positive relations between P/PET and ET were observed with the highest July ET rates occurring under P/PET ~1. However, during months with P/PET > 1, increased P/PET was associated with decreased July ET. With respect to 30-year mean values of air temperature and P in the area, both dry and wet, cool and warm growing seasons (GS) were observed. No clear trends between ET values and GS wetness/coldness were found, but all wet GS were characterized by peak growing seasons with high daily ET variability.  相似文献   

江南造山带(湖南段)金矿成矿规律与资源潜力   总被引：1，自引：0，他引：1  

黄建中  孙骥  周超  陆文  肖荣  郭爱民  黄革非  谭仕敏  隗含涛 《地球学报》2020,41(2):230-252

扬子地块—华夏地块经历武陵期—雪峰期增生造山-碰撞造山形成江南造山带,构成统一的华南板块,进入板内演化阶段。本文从构造-岩浆作用-沉积建造角度,结合地质年代学、古地磁、岩相古地理分析,加里东运动、印支运动属陆内作用,造就了加里东期、印支期两次主要的金矿成矿事件。湖南雪峰山—幕阜山(俗称“金腰带”)加里东期和印支晚期金矿床分区成带产出,构成一条复合型造山型金矿带。区域性构造导矿、次级构造交汇或叠加控矿明显;矿石普遍发育条带状构造,属韧性剪切递进变形的产物。通过对区域成矿背景、金矿成矿理论,金矿床(体)地质特征,结合同位素地球化学、地质找矿成果及深部验证情况等多方面研究表明该成矿带深部找矿潜力巨大,2000 m以浅金远景资源量有望达到3000 t。  相似文献   

Deposition and preservation of fluvio-tidal shallow-marine sandstones: A re-evaluation of the Neoproterozoic Jura Quartzite (western Scotland)     

Bruce K. Levell  Howard D. Johnson  Daniel S. Collins  Marijn van Cappelle 《Sedimentology》2020,67(1):173-206

The 2 to 5 km thick, sandstone-dominated (>90%) Jura Quartzite is an extreme example of a mature Neoproterozoic sandstone, previously interpreted as a tide-influenced shelf deposit and herein re-interpreted within a fluvio-tidal deltaic depositional model. Three issues are addressed: (i) evidence for the re-interpretation from tidal shelf to tidal delta; (ii) reasons for vertical facies uniformity; and (iii) sand supply mechanisms to form thick tidal-shelf sandstones. The predominant facies (compound cross-bedded, coarse-grained sandstones) represents the lower parts of metres to tens of metres high, transverse fluvio-tidal bedforms with superimposed smaller bedforms. Ubiquitous erosional surfaces, some with granule–pebble lags, record erosion of the upper parts of those bedforms. There was selective preservation of the higher energy, topographically-lower, parts of channel-bar systems. Strongly asymmetrical, bimodal, palaeocurrents are interpreted as due to associated selective preservation of fluvially-enhanced ebb tidal currents. Finer-grained facies are scarce, due largely to suspended sediment bypass. They record deposition in lower-energy environments, including channel mouth bars, between and down depositional-dip of higher energy fluvio-ebb tidal bars. The lack of wave-formed sedimentary structures and low continuity of mudstone and sandstone interbeds, support deposition in a non-shelf setting. Hence, a sand-rich, fluvial–tidal, current-dominated, largely sub-tidal, delta setting is proposed. This new interpretation avoids the problem of transporting large amounts of coarse sand to a shelf. Facies uniformity and vertical stacking are likely due to sediment oversupply and bypass rather than balanced sediment supply and subsidence rates. However, facies evidence of relative sea level changes is difficult to recognise, which is attributed to: (i) the areally extensive and polygenetic nature of the preserved facies, and (ii) a large stored sediment buffer that dampened response to relative sea-level and/or sediment supply changes. Consideration of preservation bias towards high-energy deposits may be more generally relevant, especially to thick Neoproterozoic and Lower Palaeozoic marine sandstones.  相似文献   

微生物勘探技术在潮汕坳陷油气勘探中的应用初探     

赵忠泉  孙鸣  万晓明  陈胜红  赵静  宋立军  李辉  强昆生  梁永兴 《中国地质》2020,47(3):645-654

东沙海域潮汕坳陷中生界研究程度相对较低,油气分布规律不明,为了加强对该区油气分布和富集规律的研究,针对潮汕坳陷西部地质目标首次应用微生物地球化学勘探技术(MGCE),探讨其含油气性。MGCE技术以轻烃微渗漏理论为基础,采用地质微生物学方法和地球化学方法检测研究区海底表层的微生物异常和吸附烃异常,预测研究区下伏地层中油气的富集区及其油气性质。检测结果显示研究区西部凹陷的斜坡区微生物异常呈块状发育,轻烃微渗漏强度变化大,可能为潜在油气富集区,酸解吸附烃成果显示可能的油气性质为干气和凝析油气。  相似文献   

城镇增长下的收缩：以武汉为例     

高喆  尹宁玮  童馨仪  李东欣  顾江 《热带地理》2019,39(1):29-36

首先从人口、经济、用地3个维度综合考察武汉市增长与收缩的全貌，并采用县区及街道2个尺度的数据定量描述了武汉市增长与收缩的特征与空间格局，发现武汉市下辖青山区、硚口区、汉阳区和蔡甸区存在局部较严重的收缩现象，空间上形成集聚，形态上呈“穿孔式”。进一步以青山区为案例，着重从资本视角探讨发生局部收缩的内在机制，发现其存在老龄化、少子化趋势，但局部收缩的主因是资本从产业部门的“逃逸”。  相似文献   

Robust numerical implementation of a 3D rate-dependent model for reservoir geomechanical simulations     

Giovanni Isotton  Pietro Teatini  Massimiliano Ferronato  Carlo Janna  Nicolò Spiezia  Stefano Mantica  Giorgio Volonte 《国际地质力学数值与分析法杂志》2019,43(18):2752-2771

A 3D elasto-plastic rate-dependent model for rock mechanics is formulated and implemented into a Finite Element (FE) numerical code. The model is based on the approach proposed by Vermeer and Neher (A soft soil model that accounts for creep. In: Proceedings of the International Symposium “Beyond 2000 in Computational Geotechnics,” pages 249-261, 1999). An original strain-driven algorithm with an Inexact Newton iterative scheme is used to compute the state variables for a given strain increment.The model is validated against laboratory measurements, checked on a simplified test case, and used to simulate land subsidence due to groundwater and hydrocarbon production. The numerical results prove computationally effective and robust, thus allowing for the use of the model on real complex geological settings.  相似文献   

Sedimentary and geochemical characterization of Middle–Late Miocene formations in the Neogene Tsugaru Basin,Japan by means of DTH27‐1 well sediment analysis     

Paolo Martizzi  Shun Chiyonobu  Hiroyuki Arato 《Island Arc》2020,29(1)

Middle–Late Miocene age siliceous formations outcropping along the northwestern side of Honshu Island are considered prospective source rocks for hydrocarbons. An analysis of geophysical, sedimentological, and geochemical properties is essential to evaluate the formations' source potential, and to understand the factors that determined the accumulation and preservation of organic matter. This study investigates the Middle–Late Miocene geological record of the Tsugaru back‐arc basin, located in the western part of Aomori prefecture, through an analysis of a 200 m long portion of a core from the DTH27‐1 well; this core is composed of the diatomaceous siltstones of the Akaishi Formation and the siliceous mudstones of the Odoji Formation. Sedimentological and geophysical characterization showed that the Akaishi Formation's diatomaceous siltstones are mostly massive and bioturbated, have low magnetic susceptibility, and demonstrate moderate natural radioactivity. Although the Odoji Formation's siliceous mudstones are massive, they have exceedingly low magnetic susceptibility and high natural radioactivity. Geochemical data from a Rock‐Eval Pyrolysis such as total organic carbon and generative potential (S1 + S2) revealed that, in the Tsugaru area, only the Odoji Formation is a likely prospective source rock for hydrocarbons. On the other hand, T_max values indicate that both the formations are thermally immature for generating hydrocarbons. The difference between the Akaishi and Odoji Formation in the sedimentological facies, in terms of the degree of bioturbation and the organic carbon content, indicates variations in lithological properties, such as porosity and grain size; moreover, this difference indicates a variation in the paleo‐oxygenation of bottom waters, with the transition from oxygen‐deficient conditions in the Middle Miocene to the more oxygenated conditions in the Late Miocene. Both the lithological and paleo‐environmental factors possibly influenced the organic richness in the two formations.  相似文献   

利用偏光显微镜反射光系统观察黑色生油岩电子探针薄片中的生烃母质特征     

郑庆华  刘行军  刘乔  梁秀玲  张小龙  左琴  杨开艳  马婷  许锋 《岩矿测试》2020,39(3):442-450

鄂尔多斯盆地上三叠统延长组长7油层组的黑色泥岩、油页岩等黑色生油岩薄片中的生烃母质,因黑色石油、沥青等黑色有机质的覆盖或不透明,导致其在偏光显微镜透射光系统下观察常局部或整体呈现为黑色。因此,建立一种黑色生油岩薄片中生烃母质有效观察的方法,对致密油、页岩油的生烃研究具有重要的理论和实际意义。本文提出了一种利用电子探针薄片和偏光显微镜的反射光系统观察黑色生油岩中生烃母质特征的方法。该方法能够克服黑色生油岩薄片中生烃母质因被黑色有机质覆盖或不透明,而在偏光显微镜的透射光系统下局部或整体呈黑色的弊端,能够对生烃母质的大小、形态、结构、分布和物质成分等特征进行整体且清晰的观察。实践表明,本文提出的利用偏光显微镜反射光系统观察黑色生油岩电子探针薄片中生烃母质特征的方法,简单有效,易在致密油、页岩油的生烃研究领域推广使用。  相似文献   

Wintertime rates of net primary production and nitrate and ammonium uptake in the southern Benguela upwelling system     

RF Flynn  JM Burger  K Pillay 《African Journal of Marine Science》2018,40(3):253-266

The elevated levels of primary productivity associated with eastern boundary currents are driven by nutrient- rich waters upwelled from depth, such that these regions are typically characterised by high rates of nitrate-fuelled phytoplankton growth. Production studies from the southern Benguela upwelling system (SBUS) tend to be biased towards the summer upwelling season, yet winter data are required to compute annual budgets and understand seasonal variability. Net primary production (NPP) and nitrate and ammonium uptake were measured concurrently at six stations in the SBUS in early winter. While euphotic zone NPP was highest at the stations nearest to the coast and declined with distance from the shore, a greater proportion was potentially exportable from open-ocean surface waters, as indicated by the higher specific nitrate uptake rates and f-ratios (ratio of nitrate uptake to total nitrogen consumption) at the stations located off the continental shelf. Near the coast, phytoplankton growth was predominantly supported by ammonium despite the high ambient nitrate concentrations. Along with ammonium concentrations as high as 3.6 µmol l^–1, this strongly suggests that nitrate uptake in the inshore SBUS, and by extension carbon drawdown, is inhibited by ammonium, at least in winter, although this has also been hypothesised for the summer.  相似文献   

Greenhouse Gas Emission During Composting and Vermicomposting of Organic Wastes – A Review          下载免费PDF全文

Ankita Swati  Subrata Hait 《洁净——土壤、空气、水》2018,46(6)

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