Use of drones to analyse sedimentary successions exposed in the foreshore

Drones have revolutionised the gathering of geoenvironmental data over the last decade. To date, the majority of drone studies of sedimentary rock successions have focussed on well-exposed vertical to subvertical cliff sections. Here, we describe a fundamental method to obtain new data and perspectives on sedimentary successions exposed in partially-obscured foreshore or other horizontal to subhorizontal outcrop surfaces using drones. We illustrate the technique using an example from foreshore exposures of Jurassic strata near Helmsdale, Scotland, UK. Our method aims to make the process of safely collecting drone footage accessible and covers practical considerations from pre-field preparation to data processing. Capturing drone imagery in a foreshore setting involves trade-offs between the time of day which constrains the lighting, the time of year which determines algal cover and tidal range, and the flight time available which indirectly governs image resolution. We show how: (1) orthomosaic images can be used to view sedimentary deposits at different scales and angles enabling identification of large-scale sedimentary features marked by small-scale changes in orientation and lateral variability; (2) production of digital elevation models permits differentially weathered features covered by water or algae to be distinguished, and (3) drones can be used for close up photography of inaccessible features.     

Analysis of lineaments within the Wajid Group,SW Saudi Arabia,and their tectonic significance

The Wajid Group is a Cambro-Permian sedimentary succession in southwest Saudi Arabia. This group is a well-known groundwater aquifer in the Wadi Al-Dawasir and Najran areas. The group also represents siliciclastic hydrocarbon reservoirs in the Rub' Al-Khali Basin. The Wajid Group is exposed in an area extending from Wadi Al-Dawasir southward to Najran city. This study aims to map and characterize the lineament traces of the Wajid Group outcrops. Landsat-8 OLI/TIRS satellite images with 30-m resolution, Spot-5 satellite images with 2.5-m resolution and SRTM digital elevation models (DEM) with 30-m resolution were used for lineament trace detection. Those lineament traces supplemented by aeromagnetic lineaments detected from reduced to pole magnetic anomaly map of the studied outcrop. Multi-scale lineament trace maps were generated, and the lineament datasets, including orientation and length, were analyzed statistically. Eight lineament trace trends were identified including NW-SE, NNW-SSE, N-S, NNE-SSW, NE-SW, ENE-WSW, E-W, and WNW-ESE. The northerly, northwesterly, and northeasterly trending lineament traces are predominant. The lineament trace lengths are generally followed the power law distribution. The lineament trace trends were validated through field investigation of the Wajid Group outcrop. The reported outcrop fracture trends are consistent with major lineament trace trends. Lineaments within the Wajid Group outcrop are also consistent with those of the southern portion of the Arabian Shield. The results of this study provide insight into the tectonic origin of the Wajid Group outcrop lineaments, and understanding of the lineaments distribution which can help to predict the fluid flow behavior within the groundwater fractured aquifers or hydrocarbon fractured reservoirs in Rub’ Al-Khali Basin.     

The discovery of Isocrinus cf. robustus from the Lias Group (Lower Jurassic) near Dunrobin Castle, Sutherland, Scotland

A single stem section (pluricolumnal) belonging to a post-Palaeozoic crinoid (sea lily) is reported from a small outcrop of Lower Jurassic Lias Group strata exposed in low cliff near Dunrobin Castle. This is the first Jurassic crinoid recorded from Eastern Scotland and the small fragment has enough diagnostic characters to be assigned to the species Isocrinus cf. robustus; a crinoid found commonly in the Lower Jurassic of England. The Scottish form collected has unusual morphology that is atypical of the genus.     

The exposures of Ludlow rocks and associated beds at Tites Point and near Newnham,Gloucestershire

The Leintwardine and Whitcliffe Beds of the Ludlow Series outcropping at Tites Point and near Newnham, Gloucestershire, are described and compared with similar beds exposed at May Hill. Data from the Brookend Borehole, 1 ½ miles (2.41 km) south of Tites Point, reveal that southward thickening affects all subdivisions of the Ludlow Series. The occurrence of the Ludlow Bone Bed in the Tites Point outcrop is also recorded.     

谈女星介(Cypridea)在我国出现的最低层位

Cypridea(女星介 )分布在世界许多国家和地区。它的最早出现时代 ,除欧洲为中侏罗世外 ,都见于晚侏罗世。在我国Cypridea分布广泛 ,已在辽、吉、黑、京、冀、晋、蒙、沪、鲁、苏、皖、浙、赣、闽、豫、鄂、湘、粤、桂、琼、滇、川、陕、甘、宁、青、新等 2 7个省、市、自治区以及渤海、黄海海域发现。关于Cypridea在我国出现的最低层位有着不同的意见 ,或上侏罗统或下白垩统。究其原因 ,或是对生物群认识上的分歧 ,或是对含化石地层划分上的异议。通过对四川、湖北、冀北、辽西、甘肃河西走廊、青海、陕甘宁盆地、新疆及东南沿海Cypridea出现最低层位的分析 ,将它们中女星介出现的相同、相似的属种与英国Purbeck层CinderBedsMember上下层位的带化石对比 ,确定了我国晚侏罗世及晚侏罗—早白垩世临界时的生物群 ,从而确认Cypridea在我国出现的最低层位为上侏罗统。     

翼龙类翼膜的折叠，褶皱以及物质特性

Preservation of wing membranes in pterosaurs is only reported from a few localities in the world, namely from the Karatau Hills, Kazakhstan (Upper Jurassic), from the Solnhofen Lithographic Limestone, Germany (Upper Jurassic), the Daohugou Beds of China (Upper Jurassic or Lower Cretaceous) and the Crato and Santana Formations, Chapada do Araraipe, NE Brazil (Lower Cretaceous).     

The Jurassic orthopteran Allaboilus gigantus Ren and Meng, 2006 (Prophalangopsidae) from Beipiao,Northeast China and its biostratigraphical significance

The orthopteran Allaboilus gigantus Ren and Meng, 2006 (Prophalangopsidae) is reported based on a male forewing from the Middle-Upper Jurassic Haifanggou Formation of Beipiao, western Liaoning, China. This discovery greatly extends the distribution of the species from Daohugou in Inner Mongolia eastwards to Beipiao in western Liaoning. It further provides new evidence for correlation of the Daohugou Beds with the Haifanggou Formation indicating a Callovian-early Oxfordian age for the Daohugou Beds.     

Ordovician and Silurian lithofacies and base‐metal deposits of the Lachlan Fold Belt

Two lithofacies maps of the Lachlan Fold Belt, one for the Ordovician and one for the Silurian, are illustrated. Both maps indicate shorelines in western New South Wales, Victoria and Tasmania.

The Ordovicoan map suggests open‐sea conditions eastwards from the shoreline with one major and two minor andesitic volcanoes (or volcanic centres). The Silurian map suggests segmentation of the Lachlan Fold Belt into the Melbourne Basin, Omeo Land, Newell Basin, and Budawang Land. The Newell Basin displays a nearshore (Louth‐Mitta Mitta) coarse clastics facies and an offshore (Wellington‐Cooma) platform carbonate facies. Acid volcanism was widespread over the Newell Basin in Silurian time, but did not occur in the Melbourne Basin.

The Louth‐Mitta Mitta and Wellington‐Cooma facies boundary coincides with the position of the Coolac‐Honeybugle Serpentine Belt and the outcrop area of the Girilambone Beds, suggesting that these features were already in some way prominent during the Silurian Period: the Serpentine Belt may have been a fault, and the Girilambone Beds may have been land.

The origin of base‐metal deposits in the Silurian rocks is thought to be somehow related to the heat generated in the subsurface during Silurian time as is indicated by the volcanism and granite intrusion; and also to the fact that the deposits occur in a transgressive sequence which contains the first phase of acid volcanism in the known geological history of the Lachlan Fold Belt.     

利用Q型聚类分析研究鄂尔多斯盆地多种能源矿产间的关系

为揭示鄂尔多斯盆地多种能源矿产间的关系,根据盆地石油、油气伴生水以及煤、煤层夹矸、铀矿及围岩样品的氯仿沥青中57种元素的分析结果,进行了Q型聚类分析。结果表明：侏罗系下统延安组石油、侏罗系中统直罗组石油与三叠系延长组石油有相近的成因特征;三叠系延长组石油沥青、三叠系延长组含油砂岩沥青与侏罗系中统直罗组石油沥青具有类似的成因特征;神木侏罗系下统延安组煤沥青、东胜侏罗系中统直罗组煤沥青、铜川陈家山侏罗系下统延安组煤层石油以及铜川陈家山侏罗系下统延安组煤沥青成因特征相近;铜川陈家山侏罗系下统延安组煤层石油沥青可能与准格尔黑岱沟石炭二叠系煤沥青具有成因上的联系;侏罗系下统延安组石油沥青与放射性铀矿的形成具有密切关系;天然气的物质来源复杂,且与石油和煤的进一步演化有一定关系。鄂尔多斯盆地多种能源矿产成因较复杂、相互问关系密切,且具有多源性成藏（矿）特征。     

The Hellenic ophiolites: eastward or westward obduction of the Maliac Ocean, a discussion

Ophiolitic bodies in the Dinaro-Hellenic mountain belt are among the most important ones in the Peri-Mediterranean Alpine chains. The characteristic feature of this ophiolitic belt is its Middle to Late Jurassic age of obduction. The ophiolitic bodies form two major belts on each side of the Pelagonian zone: an east Pelagonian belt in the Vardarian domain and a Supra-Pelagonian ophiolitic belt (SPO) to the west. The different hypotheses relative to the origin of the SPO present geodynamic evolution models accounting for most of the available data: a mid-Triassic episode of rifting; a Ladinian–Jurassic episode of sea-floor spreading forming notably the Maliac Ocean; a Middle to Late Jurassic convergent period with subduction and obduction episodes, and finally, a late episode of Tertiary compressional deformation responsible for the westward thrusting of the Jurassic ophiolitic nappes over the external zones. Despite many studies dating from the early 1970s, the eastern or western Pelagonian origin of these ophiolites, especially the SPO, is still under dispute. Whatever the adopted hypothesis, we consider that the main SPO bodies (N-Pindos, Vourinos, Othris, Evia, Argolis) have the same origin because of their geographic continuity and of the similarities in their geological characteristics. We propose that this ocean corresponds everywhere to the Maliac Ocean, defined in Othris from the well-preserved sedimentary (oceanic margin) and ophiolitic nappes thrust during the Late Jurassic obduction onto the Pelagonian platform. There is strong evidence for the existence of two deep basins on both sides of the Pelagonian continental ridge during Triassic–Jurassic times. They correspond, respectively, to the Vardar area to the east and the Pindos domain to the west, one of these domains being at the origin of the SPO. The hypothesis of an eastward emplacement of the SPO from the Pindos domain is based mainly on sedimentological data from the margin series and on structural analyses of ophiolitic bodies. However, we conclude the westward obduction of the Maliac Ocean, originating from the Vardar area, to be the best fitting model. This westward model is supported by paleogeographic and structural constraints on regional scale. Notably, the absence of obducted ophiolites in the Jurassic series of the Koziakas units (units attributed to the western Pelagonian margin) and of the Parnassus domain (on the eastern side of the Pindos basin) is difficult to reconcile with an eastward obduction from the Pindos domain. Other observations, such as the distribution of ophiolitic detritus in the internal and external zones, also promote the westward Late Jurassic obduction of the Maliac Ocean. Our preferred model offers a consistent explanation for the mechanism and timing of the emplacement of the SPO, as well as providing insight on the origin and emplacement of the Vardarian ophiolites. Following this hypothesis, there is no need for a clear boundary between the SPO and the west Vardarian ophiolitic bodies as they were obducted from the same oceanic basin and during the same Jurassic tectonic event. In this paper, we develop evidence in favor of the eastern Pelagonian origin for the SPO (our adopted model) and provide discussion on the data supporting the main alternative hypothesis (western origin for the SPO).     

西北侏罗纪盆地沉积层序演化与储层特征

笔者研究了西北侏罗纪盆地沉积层序及储层特征,根据露头观察,井下实钻资料及实验室内分析结果,提出中,下侏罗统主要为湖沼相含煤碎屑岩沉积,主要发育河流中冲积相及三角洲相的砂岩集集体,上统为红色或杂色碎屑岩,侏罗纪计导氏孔低渗为主的富含火山岩屑的碎屑岩,局部可发育较好砂岩储层,侏罗系本身可构成妨好的生储盖组合。     

Integration of sedimentology and ground‐penetrating radar for high‐resolution imaging of a carbonate platform

Ground‐penetrating radar has not been applied widely to the recognition of ancient carbonate platform geometries. This article reports the results of an integrated study performed on an Upper Jurassic outcrop from the south‐east Paris basin, where coral bioherms laterally change into prograding depositional sequences. Ground‐penetrating radar profiles illustrate the different bedding planes and major erosional unconformities visible at outcrop. A ground‐penetrating radar profile conducted at the base of the cliff displays a palaeotopographic surface on which the outcropping bioherms settled. The excellent penetration depths of the ground‐penetrating radar (20 m with a monostatic 200 MHz antenna) images the carbonate platform geometries, ranging between outcrop workscale (a few metres) and seismic scale (several hundreds of metres). This study supports recent evidence of icehouse conditions and induced sea‐level fluctuations controlling the Upper Jurassic carbonate production.     

Stratigraphic subdivision and correlation of the upper part of the Willyama Complex,New South Wales

Within the complexly deformed and metamorphosed middle Precambrian Willyama Complex in western New South Wales, two distinct sedimentary sequences are recognized at the top of the succession. The fine‐grained carbonaceous Bijerkerno Beds conformably overlie a very thick psammopelitic unit termed the Wookookaroo Beds. These two sequences record different depositional histories, though they probably have similar source areas. The base of the Wookookaroo Beds is terminated against a significant tectono‐stratigraphic boundary, which may represent a major stratigraphic break within the Willyama Complex. Beneath this boundary, felsic and mafic gneisses and high‐grade metasediments are correlated with mine‐sequence rocks such as are developed within the vicinity of the main Broken Hill lode. Correlations between the stratigraphy, as established at Bijerkerno, and other areas from the Willyama Complex, help provide a fuller understanding of this Precambrian terrain.     

Laminaset geometries in fine grained shallow marine sequences: core data from the Rannoch Formation (North Sea) and outcrop data from the Kennilworth Member (Utah, USA) and the Bencliff Grit (Dorset, UK)

Sandbodies from storm-dominated marine and marginal marine environments commonly contain intervals of laminated fine sandstones. A characteristic of such lamination is the presence of low angle cross lamination. In order to model correctly the effects of such lamination on a waterflood of an oil-bearing shoreface sequence it was necessary to quantify the geometry of the laminaset elements. This challenge has been greatly complicated by the lack of outcrop of the formation of interest. The Middle Jurassic Rannoch Formation of the North Sea only occurs in the subsurface where it is not possible in core to measure the aspect ratio of laminasets directly. In this study, the laminaset geometry data that can be obtained from core (e.g. apparent set thicknesses) were collected for the Rannoch Formation. These data were compared with similar data from potential outcrop analogues in (1) the Cretaceous Kennilworth Member of the Blackhawk Formation in Utah, USA and (2) the Upper Jurassic Bencliff Grit from the Dorset coast, UK. A quantitative analysis of laminaset geometries has been used to compare subsurface core with potential outcrop analogues. The Rannoch Formation core is characterized by numerous low angle truncations. We have measured these features in two wells (means of 7.2° and 12.1°). Mean apparent set thicknesses were 0.24 and 0.19 m. In the outcrop sections studied, truncation angles ranged from 9.6° to 13.4° and mean set thicknesses from 0.24 to 0.34 m. Mean bounding surface dips of 5.8° and 8.6°, and mean laminaset lengths of 2.3 and 4.1 m were also measured. directly in the field and by using photomosaics. On the basis of this comparison, the Kennilworth Member in Utah was found to be the most suitable and the geometries (i.e. aspect ratios) measured there were used to generate an appropriate geometry of Rannoch laminaset geometries for use in engineering studies: laminaset length, 2.0 m; laminaset thickness, 0.2 m.     

Architectural element analysis within the Kayenta Formation (Lower Jurassic) using ground-probing radar and sedimentological profiling, southwestern Colorado

A well exposed outcrop in the Kayenta Formation (Lower Jurassic) in southwestern Colorado was examined in order to delineate the stratigraphy in the subsurface and test the usefulness of ground-probing radar (GPR) in three-dimensional architectural studies.

Two fluvial styles are present within the Kayenta Formation. Sandbodies within the lower third of the outcrop are characterized by parallel laminations that can be followed in the cliff-face for well over 300 m. These sandbodies are sheet-like in appearance, and represent high-energy flood deposits that most likely resulted from episodic floods. The remainder of the outcrop is characterized by concave-up channel deposits with bank-attached and mid-channel macroforms. Their presence suggests a multiple channel river system.

The GPR data collected on the cliff-top, together with sedimentological data, provided a partial three-dimensional picture of the paleo-river system within the Kayenta Formation. The 3-D picture consists of stacked channel-bar lenses approximately 50 m in diameter.

The GPR technique offers a very effective means of delineating the subsurface stratigraphy. Its high resolution capabilities, easy mobility, and rapid rate of data collection make it a useful tool. Its shallow penetration depth and limitation to low-conductivity environments are its only drawbacks.     

Geomechanical paleostress inversion using fracture data

We describe a fast geomechanically-based paleostress inversion technique that uses observed fracture data to constrain stress through multiple simulations. The method assumes that the local stress field around individual fractures is heterogeneous and derives the far field tectonic stress, that we also call the far field boundary conditions. We show how such far field tectonic stress can be recovered through a mechanical stress inversion technique using local observations of natural fractures (i.e. mechanical type, orientation and location). We test the paleostress inversion against outcrop analogues of fractured carbonates from both Nash Point, U.K., where there are well exposed faults and joints and the Matelles, France, where there are well exposed faults, veins and stylolites. We demonstrate through these case studies how the method can be efficiently applied to natural examples and we highlight its advantages and limitations. We discuss how such method could be applied to subsurface problems and how it can provide complementary constraints to drive discrete fracture models for better fractured reservoir characterization and modelling.     

准噶尔盆地四棵树剖面孢粉组合及三叠系-侏罗系界线

在实测四棵树剖面的基础上,详细研究了其孢粉组合特征,建立了5个孢粉组合:1)Cameratitriletes和Zonotriletes-Protopinus-Cycadopites组合,2)Cyatheaceae-Pinaceae-Cycadopites组合,3)Cyatheaceae-Pinaceae-Quadraeculina-Cycadopites组合,4)Cyatheaceae-Quadraeculina-Piceaepollenites组合和5)Cyatheaceae-Clas-sopollis-Pinaceae组合,分别产于上三叠统的小泉沟群、下侏罗统的八道湾组和三工河组、中侏罗统的西山窑组和头屯河组。根据孢粉组合特征,结合岩性和沉积及区域资料,将三叠系-侏罗系界线定于38层和39层之间。     

Vitrinite reflectance as a tool for determining level of thermal maturity for the Upper Jurassic Naokelekan and Barsarin Formations in Sargelu location,Kurdistan Region,NE Iraq

Ten samples from the Upper Jurassic Naokelekan and Barsarin Formations in an outcrop section near Sargelu Village were studied to evaluate their thermal maturity using vitrinite reflectance method. The studied beds appeared to be mature and within the oil generation window (0.79–1.25 % vitrinite reflectance in immersion oil (Ro)). Some of the reflectance histograms showed bimodal distribution indicating existence of nonindigenous populations which were all ignored during the measurements of the mean value of Ro. Comparison between the results obtained from vitrinite reflectance method and some other methods like pyrolysis and gas chromatography showed variations which finally more reality believed to be for the vitrinite reflectance method.     

Eruptive environments and inferred exploration potential of metabasalts from New South Wales

The Honeysuckle Beds, Jindalee Beds, Woolomin Beds and Nambucca Beds all contain metavolcanic units of dismembered ophiolite suites in the Palaeozoic of New South Wales. It is assumed that no major changes in the distribution of stable trace elements have taken place during metamorphism. Geological evidence and stable trace element data indicate that the Honeysuckle and Jindalee Beds may contain metabasalts of marginal basin origin whereas the Woolomin and Nambucca Beds may contain metabasalts erupted during the opening phase of a major ocean. Comparison with massive sulphide-bearing metabasalts elsewhere suggests that the Honeysuckle Beds and Jindalee Beds, which chemically resemble metabasalts from the Troödos Massif of Cyprus, have the greatest exploration potential.