Quaternary Gravel Deposits Research Articles

Structural geology of the Upper Cretaceous Chalk Central Mass, Isle of Wight, U.K.

Remapping the Chalk of the Central Chalk Mass of the Isle of Wight between Carisbrooke (Newport), Calbourne and Shalcombe, including the Bowcombe Valley, has identified a complex series of tectonic ‘rolls’ and ‘flats’ in a region that has been interpreted to be a relay ramp between the Needles and the Sandown faults. A major new WNW trending fault at Cheverton throws the Chalk down by >50 m to the SW in a 80–100 m wide zone of faulting within which some chalk blocks have near vertical dips. The fault location and trend closely follows the edge of the Cranbourne–Fordingbridge High and could also reflect, for the first time, the surface expression of part of the Needles Fault, a major inversion reverse fault. Located along this fault zone deep Quaternary weathering of the Chalk and Quaternary gravel deposits are present. The trend of the Cheverton Fault brings it towards Gotten Leaze where a groundwater pumping station is located and groundwater springs regularly cause flooding on the Brighstone–Calbourne Road. Analyses of the jointing in the Chalk show that stratabound fracture patterns typical of the Chalk formations elsewhere in Southern England are present in the Central Mass. In addition, there are numerous small faults along which valleys have formed. Tectonic structure and lithology have had a profound influence on the geomorphology and groundwater flow in the Chalk in the Central Mass.

満洲における日本の石油探鉱

Japan hunted oil in Manchuria before World War II. In 1927 Japanese geologist found scattered asphalt in vugs of basalt and quaternary gravel deposits on the north western shore of Hulun Nur (lake), NW Manchuria. Geological Survey of China made a check survey of the area, and found the same asphalt in 1931.After establishment of Manchukuo, geological survey, tortion balance and refraction seismograph survey, and drilling were conducted during 1932-1941. One deep well (1,114 m TD) and 21 core holes were drilled on the northern shore of the lake, but no potential oil were found.That the core hole drilled in Fuxin coal mine hit oil shows in 1938, led to extensive oil exploration program. Geological field party mapped a broad anticline located on east of Fuxin, and the core hole drilled on the anticline recovered some 30 m thick sandstones (100-200 m in depth) impregnating with oil. To explore this oil called on massive drilling campaign, and 47 or more wells were drilled on this anticline, but the reservoir quality was not good enough to establish commercial production. It is noteworthy to point out that the geologists engaged in Fuxin oil exploration thought that the oil came from Jurassic shales deposited in fresh water lake.In 1940 oil shows were found in the water wells near Chengde, and a one-month field check survey was conducted, and mapped a small anticline in Jurassic shales, but no further exploration was conducted.

Hierarchical dynamic stratigraphy in various Quaternary gravel deposits, Rhine glacier area (SW Germany): implications for hydrostratigraphy

The approach of ‘dynamic stratigraphy’ aims to understand genetic processes that form stratigraphic units in a hierarchy of spatial and temporal scales. This approach was used to investigate Quaternary gravel deposits in terms of their sedimentology and in order to characterize the various sedimentary units in terms of their hydrogeological properties. Facies analysis within 62 gravel pits, laboratory permeability measurements of field samples and geophysical surveys (3-D georadar, 2-D seismic reflection) led to the detection and classification of sedimentary heterogeneity according to the following six scales whereby each scale can be translated into defined hydrostratigraphic units. (1) Particles and pores (micro scale) that reflect depositional and diagenetic fluid dynamics as well as source material behaviour (e.g. grain-size, roundness, lithological composition). This was found to be important for the hydrogeochemistry of groundwater in gravel aquifers (e.g. higher sorption capacity of carbon-rich limestone particles for organic pollutants). (2) Strata (meso scale) contain the recognition of sorting, fabric, texture and stratinomic features, which can give an indication of transport and depositional dynamics. Five major lithofacies groups, for example, were distinguished within fluvial gravel-bed deposits. Their variable hydraulic properties led to their subdivision into 12 hydrofacies types. They form the smallest mappable hydrostratigraphic units, which may result in either preferred pathways for fluid flow or flow barriers. (3) Depositional elements (macro scale) enable reconstruction of sedimentary/geomorphic elements and their dynamics within a depositional system (e.g. gravel-bed braided river systems are dominated by gravel sheet, gravel dunes and scour pool depositional elements). Hydrostratigraphically, the architecture of depositional elements influences the hydraulic connectivity and local permeability structure/distribution within an aquifer body. Five types of depositional elements in fluvial gravel-bed deposits were distinguished and their geometries/dimensions quantified. (4) Facies bodies (mega scale) composed of a stack of depositional elements and strata recording distinct environmental systems and their dynamics (e.g. a coarse-grained prograding delta system). Hydrostratigraphically, facies bodies represent major compartments of an aquifer. Six major types of meltwater-controlled facies bodies were identified in the study area. (5) Genetic sequences (mega scale) reflect the shifts of depositional environments caused by allocyclic changes (e.g. glacial advance recorded by a coarsening upward sequence) or autocyclic changes of landscape shaping events. These sequences may form separate hydrostratigraphic units or aquifer storeys. (6) Basin fill (giga scale) comprising the lateral and vertical stacking of facies bodies and genetic sequences controlled by either long-term glacier dynamics or short term flood events. The regional distribution of permeable gravel units and, for example, less permeable diamicts builds the larger scale hydrostratigraphy.

Sulfate Reduction at a Lignite Seam: Microbial Abundance and Activity.

In a combined isotope geochemical and microbiological investigation, a setting of multiple aquifers was characterized. Biologically mediated redox processes were observed in the aquifers situated in marine sands of Tertiary age and overlying Quaternary gravel deposits. Intercalated lignite seams define the aquitards, which separate the aquifers. Bacterial oxidation of organic matter is evident from dissolved inorganic carbon characterized by average carbon isotope values between ?18.4 per thousand and ?15.7 per thousand (PDB). Strongly positive sulfur isotope values of up to +50 per thousand (CTD) for residual sulfate indicate sulfate reduction under closed system conditions with respect to sulfate availability. Both, hydrochemical and isotope data are thus consistent with the recent activity of sulfate-reducing bacteria (SRB). Microbiological investigations revealed the presence of an anaerobic food chain in the aquifers. Most-probable-number (MPN) determinations for SRB and fermenting microorganisms reached highest values at the interface between aquifer and lignite seam (1.5 x 103 cells/g sediment dry mass). Five strains of SRB were isolated from highest MPN dilutions. Spore-forming bacteria appeared to dominate the SRB population. Sulfate reduction rates were determined by the 35S-radiotracer method. A detailed assessment indicates an increase in the reduction rate in proximity to the lignite seam, with a maximum turnover of 8.4 mM sulfate/a, suggesting that lignite-drived compounds represent the substrate for sulfate reduction.

Relating lithofacies to hydrofacies: outcrop-based hydrogeological characterisation of Quaternary gravel deposits

Abstract A considerable part of today's drinking water supplies in Europe and North America rely on clean groundwater from gravelly valley aquifers of Quaternary age. The sedimentary architecture, the distribution of lithofacies and of architectural elements in such heterogeneous deposits are of fundamental importance for the analysis of groundwater flow and contaminant transport. As the aquifers are not directly accessible for observation, representative outcrop analogues were used to study the sedimentology on a local scale. Conventional sedimentological classification schemes were adapted for the purpose of hydrogeological evaluations. Measurements of hydraulic properties were then used to define a set of 5 hydrofacies from 23 possible sediment lithofacies. A digital-photographic mapping procedure was developed to allow fast data acquisition in the field. The sedimentologically interpreted outcrops were stored in a GIS style database and thus allow the output for further sedimentological or hydrogeological analysis.

The use of dating techniques to constrain the age of fault activity: a case history from north Somerset, United Kingdom

Abstract Attempts were made to obtain absolute ages constraining the most recent episode of fault activity in the North Somerset Coastal Fault Belt as part of the seismic hazard assessment for the proposed Hinkley Point ‘C’ power station. Radiometric (uranium series, 14 C) and palaeomagnetic dating techniques were applied to calcite from vein systems which cut the Hinkley Point Fault and 14 C dating was applied to bone material from undeformed Quaternary gravel deposits overlying faults in Liassic bedrock at Helwell Bay. Detailed field mapping and microscopy indicated that the samples chosen for dating had not undergone any significant fault-related deformation. Dates obtained from the radiometric techniques ranged from c . 33 ka to greater than 300 ka and reflect the influences of isotopic exchange and contamination as well as the inherent age limitations of the techniques. Palaeomagnetic dating techniques identified reverse polarizaton in a calcite sample from the Hinkley Point Fault, indicating an age greater than 730 ka, the time of the last geomagnetic field reversal. Palaeomagnetic vectors suggest a pre-Pliocene (and conceivably an early Jurassic) age for the calcite vein emplacement.

Mass Classification of Quaternary gravel deposits

Abstract A mass Classification index was devised to determine the variability of highly variable Quaternary gravel deposits in the Netherlands. To classify the “mass” properties trials have been carried out using the “scanline” concept. The scanline concept was verified in Spain to classify river gravel and glacial deposit mass properties such as grading, particle shape and rock type. Using a mass Classification system called the Scanline Quantification of Uniformity for Aggregate Designation or SQUAD, the scanline concept was adapted to determine representativeness of a sample with respect to the surrounding soil mass e.g. for aggregate assessment. When mapping the Quaternary gravel deposits the SQUAD values can be used to determine the confidence levels of contour lines.

Geological structure of Wairarapa Valley, New Zealand, from seismic reflection profiling

Abstract Three Mini-Sosie™ seismic reflection profiles across part of southern Wairarapa, North Island, with a combined length of 22 km roughly normal to the main structural trend, reveal shallow crustal structure down to a depth of 1.5 km in upper Cenozoic strata hidden below upper Quaternary gravel deposits. Our stratigraphic correlation of the seismic data is based on the closest mapped outcrops, as there are no deep drill-holes. (™ Trademark of Societe Nationale Elf Aquitane). A profile across the Huangarua Valley, 5 km southeast of Martinborough (Line 101,3 km long) defines an asymmetrical syncline verging southeastward and formed during the last one million years, as previously described from geological outcrop. Profiles across the Wairarapa Plain, intersecting Highway 2 at a point 3.5 km southwest of Masterton (Lines 201 and 202, combined length c. 19 km) reveal the following structures south-eastward from the Alfredton Fault at the north-western edge of the Wairarapa Plain. 1. Chester Anticline formed in upper Miocene-basal Pliocene strata, buried under the north-west flank of the Taratahi Syncline (see below). 2. Taratahi Syncline, 7 km wide, its north-west flank unconformably overlying Chester Anticline, its bottom flat and nearly level for 5 km, and its south-eastern flank rising in a concentric curve to the adjacent Peter Cooper Anticline. 3. Peter Cooper Anticline and on its south-east side the complementary Fern Hill Syncline, both concentric folds, and strongly developed in Upper Miocene and Pliocene strata, but weakly developed in Quaternary strata. We have mapped in outcrop two growing structures at the south-east side of the Wairarapa Valley (south-east end of Line 201) as the active Gladstone Anticline and Huangarua Syncline, which are well displayed in the profile. Subsidence of the region commenced near the beginning of Late Miocene time, c. 10 million years bp. There was a brief folding event in latest Miocene and/or earliest Pliocene time. There was little tectonic activity other than regional subsidence during most of Pliocene and early Quaternary time. An increase of the folding rate of nearly an order of magnitude commenced in the middle of the Quaternary, c. 1 million years ago, and continues at the present day.