Geothermal gradients and heat flow in the Beaufort-Mackenzie Basin,Arctic Canada

Thermal gradients have been calculated and heat flow estimates made for 34 petroleum exploration wells along four regional profiles crossing the Mesozoic-Cenozoic Beaufort-Mackenzie Basin of northern Canada. The geothermal gradients vary from 22 mKm^–1 to 44 mKm^–1. Four sets of possible thermal conductivity values were used to calculate a range of heat flow values for each well. Generally low heat flow is observed in wells within the deeper portions of the basin and higher heat flow values occur in wells along the Aklavik Arch Complex which forms the southeastern margin of the basin.The contribution to heat flow by heat generation below the Mesozoic-Cenozoic basin fill sediments has been considered. The heat flow contribution from sub-Mesozoic sedimentary strata and underlying basement is highest along the basin-bounding Aklavik Arch Complex. The decrease in heat flow from below the basin fill sediments toward the basin depocenter may be related to basinward crustal thinning and corresponding reductions in intra-crustal radiogenic heat production.     

Isotope hydrology of the Oldman River basin,southern Alberta,Canada

The partially semi-arid Oldman River basin (OMRB), located in southern Alberta (Canada), has an area of 28 200 km², is forested in its western headwater part, and is used for agriculture in its eastern part. Hydrometric measurements indicate that flow in the Oldman River has decreased by ∼34% between 1913 and 2003, and it is predicted that water withdrawals will increase in the next 20 years. The objective of this study was to determine whether isotope ratio measurements can provide further insight into the water dynamics of the Oldman River and its tributaries. Surface water samples were collected monthly between December 2000 and March 2003. Groundwater samples were taken from 58 wells during one-time sampling trips. Runoff within the OMRB is currently about 70 mm year⁻¹, with a corresponding runoff ratio of 0·18. Seasonal flow characteristics are markedly different upstream and downstream of the Oldman River reservoir. Upstream, sharp increases in flow in late spring and early summer are followed by a rapid decrease to base flow levels. Downstream, a prolonged high flow peak is observed due to the storage effect of the Oldman River reservoir. The seasonal variation in the isotopic composition of surface water from upstream sites is small. This suggests that peak runoff is not predominantly generated by melting snow accumulated during the preceding winter, but mainly by relatively well-mixed young groundwater. A significant increase in the δ¹⁸O and δ²H values in the downstream part of the basin was observed. The increase in the isotopic values is partly due to surface water and groundwater influx with progressively higher δ¹⁸O and δ²H values in the eastern part, and partly due to evaporation. Hence, the combination of hydrometric data with isotope measurements yields valuable insights into the water dynamics in the OMRB that may be further refined with more intensive measurement programmes in the future. Copyright © 2006 John Wiley & Sons, Ltd.     

Terrestrial heat flow in Hungary

Summary The geothermal gradient in the Carpathian Basin lies between 40–70 C/km. According to careful measurements in shafts the value of terrestrial heat flow in the southern part of Hungary is (2.055–3.066)·10^–6 cal/cm² sec. These measurements are believed the first ever attempted in continental Europe. Systematic heat flow measurement are being extended to other part of this country.     

Terrestrial heat flow in Japan

Terrestrial heat flow, Q=K×ΔT/ΔZ cal/cm² sec has been determined at 51 localities (39 on land and 12 in the sea) in and around the Japanese Islands. The average values of observed heat flow in land and sea are 1.53µ cal/cm²sec and 1.48µcal/cm²sec respectively. These value do not differ greatly from the world’s averages. The outstanding features of the heat flow distribution are as follows:a) High heat flow region (Q>2.0µcal/cm²sec) exists in the Inner Zone of the Honshu Arc. This region of high heat flow is more distinct in the northeastern Japan than in the southwestern Japan.b) The High heat flow region seems to extend, through the Fossa Magna area, down to the Izu-Mariana Arc.c) It is also probable that a similar high heat flow zone exists in the inner side of the Kurile Arc.d) These zones of high heat flow precisely coincide with the zones of the Cenozoic orogeny in the area concerned.e) Far off the coast of the northeastern Japan, the area at about 150° E may be a high heat flow region.f) Low heat flow (Q<1.0µcal/cm²sec) prevails in the Pacific coast side of the northeastern Japan and in the oceanic area directly east of it, including the area of the Japan Trench.g) The region bounded by the above mentioned high and low heat flow regions has heat flow which is more or less normal. Based on these measurements, a « steady state ” temperature distribution in the crust has been calculated for each of the above regions of high, low and intermediate heat flow, and it was found that there is a large temperature differences between the bottom of the crust of the high and low heat flow regions: the temperature at the Moho boundary in the high heat flow regions should be as high as some 800～1000°C (d=27 km), whereas that under the low heat flow region should be only about 200°C (d=23 km). The high general temperature at the Moho under the high heat flow region seems to favor a production of magma in the upper mantle. Calculated Moho temperatures disfavor the hypothesis that the Moho boundary is due to phase transition.     

查干凹陷大地热流

查干凹陷是银根—额济纳旗盆地最具勘探潜力的凹陷, 但是查干凹陷及整个银根—额济纳旗盆地的大地热流研究仍为空白, 严重制约该盆地的油气资源的评价. 本文通过测试19口井107块岩芯的岩石热导率和岩石热导率原位校正, 利用协和平均公式计算得到查干凹陷各地层的岩石热导率大小; 并利用9口井的温度数据, 结合岩石热导率数据对查干凹陷的地温梯度和大地热流进行了计算. 研究结果表明查干凹陷具有构造稳定区和构造活动区之间的中温型地温场特征, 其平均地温梯度和大地热流分别为33.6℃/km, 74.5 mW/m2. 本文的研究成果为查干凹陷及银根—额济纳旗盆地油气资源评价提供地热参数.     

Depositional process and alluvial fan-drainage basin morphometric relationships near banff,Alberta, Canada

Two distinct types of alluvial fans occur in the Bow River Valley, Alberta, Canada: fluvially dominated and debris flow dominated. Large, gently sloping fans dominated by fluvial processes are associated with large and less rugged drainage basins, and small rugged basins have produced small, steep fans dominated by debris flow processes. Quantitative analysis demonstrates that strong fan-basin morphometric relationships occur despite a short fan history. Statistical analysis of fan area-basin area relationships indicate that debris flow fan areas do not increase in size as quickly as contributing basins. The relationship of fluvial fan area to basin area is not statistically significant. However, this relationship is probably affected by fan erosion. Examination of fan slope to basin ruggedness relationships indicates that fan slope increases more rapidly than basin ruggedness for both fan types. This is likely related to non-linear discharge and sediment size effects on fluvial fans, and reworking of larger fan surfaces by fluvial processes on debris flow fans.     

Terrestrial heat flow in Hungarian Permian strata

Summary Latest measurements of terrestrial heat flow in the Hungarian and Russian parts of the Carpathian basin confirm previously measured high flow values between 2.0–3.3 cal/cm² sec. Recent measurement in the Permian anticline structure of the Mecseck. Mts. in Hungary gave 2.4 cal/cm²sec, whereas in the Russian part of the basin, near to the Hungarian border 2.6 cal/cm² sec was measured in Miocene sediments. For more than 100000 km² surface of the Carpathian basin covered by Hungary and parts of Slovakia and Russian the high heat flow is an established fact.     

Terrestrial heat flow in various parts of India

Results of heat flow studies made in different parts of India including Kolar Gold Field, Cuddapah basin, Singhbhum thrust zone, Aravalli mountain system of Precambrian age, Godavary valley of Mesozoic age and Cambay basin of Cenozoic age are discussed. Heat flow has been found to be low in the southern part of the Preambrian shield. Relatively higher values have been obtained along the northeastern (Singhbhum) and the northwestern parts of the shield (Aravallies). High heat flow has been found along the southeastern part of the Godavary valley and the Cambay basin. The correlation of heat flow with geology and tectonic history in the respective areas is discussed.     

Terrestrial heat flow in the natural steam field at Larderello

Summary Measurements of thermal gradients and rock conductivity in the steam field of Larderello, along a cross section of about 12 km length, reveal a great anomaly of terrestrial heat flow. Heat flow varies between 6 and 14 cal-cm² sec, while thermal gradients are between 200 and 800 deg C-km. The measurements show that heat flow values characterize better the productive areas than thermal gradient anomalies. Knowing the heat flow it is possible to set up the thermal balance of the steam producing area, which is of considerable importance in planning the production of the steam field.     

Terrestrial heat flow in the North Island of New Zealand

Large variations in terrestrial heat flow from 21 to 209 mW/m² have been observed over the North Island, New Zealand. This is generally in good agreement with the pattern of existing geological and geophysical observations. A high heat flow zone with a value of 92 ±3 mW/m², which corresponds to melting temperatures near the base of the crust, is delineated in the northern part of the Taranaki Basin. In the rest of the island, heat flow appears to be low to normal, but some isolated high values are also found. Observed results are interpreted in terms of crust and mantle structure in a region of plate subduction.     

Terrestrial heat flow from project CESAR, Alpha Ridge, Arctic Ocean

During two months in spring, 1983, a multidisciplinary study, project CESAR, was undertaken from the sea ice across the eastern Alpha Ridge, Arctic Ocean. In the geothermal program, 10 gradiometer profiles were obtained; 63 determinations of in situ sediment thermal conductivity were obtained with the same probe, and 714 measurements of conductivity using the needle probe method were obtained on nearby core.Weighted means of the thermal conductivity of the sediment are 1.26 W/mK (in situ) and 1.34 W/mK (core), consistent with the compacted sediment encountered across the ridge and with the lithology. Calculated terrestrial heat flow values, corrected for the regional topography, range from 37 to 72 mWm⁻²; the average is 56+/−8 mWm⁻².Some temperature and heat flow versus depth profiles exhibit non-linearities that can be explained by physically reasonable (but otherwise unsubstantiated) variations in bottom water temperatures preceding the measurements; models are hypothesized that reduce the curvatures. Two heat flow values considerably higher than others in the area may be explained by higher bottom water temperature over several years, while the low value is consistent with a recent deposition from a slump. This hypothetical modelling reduces the scatter of heat flows and reduces the average to 53+/−6 mWm⁻².The CESAR heat flow is somewhat greater than expected for a purely continental fragment but is consistent with crust of oceanic origin. The heat flow is similar to values obtained in Cretaceous back-arc basins. Based on the oceanic heat flow-age relationship, the heat flow constrains the age of the ridge to 60–120 million years. The heat flow observed on other aseismic features in the world's oceans suggests that the Alpha Ridge has experienced no significant tectono-thermal event in the last 100 million years.     

Terrestrial heat flow at Hirabayashi on Awaji Island, south-west Japan

Abstract Terrestrial heat flow at Hirabayashi in Awaji Island, south-west Japan, was investigated using the deep borehole penetrating through the Nojima Fault, which was activated during the 1995 Hyogo-ken Nanbu earthquake, by measuring the thermal conductivity of basement rocks. Using the temperature logging data, the value of terrestrial heat flow in Hirabayashi was found to be 56.6 ± 5.2 mW/m². The relationship between cut-off depth of aftershocks of the Hyogo-ken Nanbu earthquake in Hirabayashi and terrestrial heat flow are discussed. The cut-off depth roughly corresponds to isotherms of 300°C.     

Lees's topographic correction in heat flow and the geothermal flux in Tasmania

Summary Lees's topographic correction for a simple idealized hill is discussed and extended to a monoclinal structure. It is valuable as giving very simply the order of magnitude of the correction. A number of new measurements of temperature in Tasmanian boreholes has been made and the previous rather high value of over 2 cal/cm² sec for the heat flux has been confirmed. The variation of thermal conductivity through the thickness of a differentiated tholeiite sheet has been measured and found to be in reasonably good agreement with values calculated from chemical and modal analyses.     

Lateral flow thresholds for aspen forested hillslopes on the Western Boreal Plain,Alberta, Canada

To predict the long‐term sustainability of water resources on the Boreal Plain region of northern Alberta, it is critical to understand when hillslopes generate runoff and connect with surface waters. The sub‐humid climate (P ≤ ET) and deep glacial sediments of this region result in large available soil storage capacity relative to moisture surpluses or deficits, leading to threshold‐dependent rainfall‐runoff relationships. Rainfall simulation experiments were conducted using large magnitude and high intensity applications to examine the thresholds in precipitation and soil moisture that are necessary to generate lateral flow from hillslope runoff plots representative of Luvisolic soils and an aspen canopy. Two adjacent plots (areas of 2·95 and 3·4 m²) of contrasting antecedent moisture conditions were examined; one had tree root uptake excluded for two months to increase soil moisture content, while the second plot allowed tree uptake over the growing season resulting in drier soils. Vertical flow as drainage and soil moisture storage dominated the water balances of both plots. Greater lateral flow occurred from the plot with higher antecedent moisture content. Results indicate that a minimum of 15–20 mm of rainfall is required to generate lateral flow, and only after the soils have been wetted to a depth of 0·75 m (C‐horizon). The depth and intensity of rainfall events that generated runoff > 1 mm have return periods of 25 years or greater and, when combined with the need for wet antecendent conditions, indicate that lateral flow generation on these hillslopes will occur infrequently. Copyright © 2008 John Wiley & Sons, Ltd.     

北京平原区西北部大地热流与深部地温分布特征

北京平原区蕴藏着丰富的中-低温水热型地热资源,其西北部分布着小汤山地热田和京西北地热田,两大地热田以南口—孙河断裂带为界.地热田及其外围地区基础的地热地质研究工作较少.为给地热学研究和地热资源精细勘探提供科学依据,本文基于前人23眼钻孔的温度测量数据以及近期完成的548件热导率和100件放射性生热率实测数据,研究了区域大地热流和0~4 km深部地温特征.结果表明：（1）研究区现今地温梯度为11.31~94.89℃·km^-1,平均值为31.79℃·km^-1;岩石热导率为0.895~5.111 W·（m·K）^-1,放射性生热率为0.257~2.305 μW·m^-3,大地热流为48.1~99.1 mW·m^-2,平均值为68.3 mW·m^-2,热流的分布受基底形态和断裂构造控制.研究区东部南口—孙河断裂带两侧小汤山和郑各庄地区为高热流异常区,中部马池口地区也存在局部高热流异常区.（2）在南口—孙河断裂带的不同位置,不同深度地层温度差异明显,体现出区域现今地温场不只受控于该活动断裂,更是多期次构造事件复合叠加的结果.（3）南口—孙河断裂带南侧存在两处有意义的较高地温异常区,分别为郑各庄异常区和马池口异常区,其中马池口异常区是未来地热开发利用有一定潜力的地区.

     

延庆盆地大地热流异常及其构造背景

基底构造探测对地热成因机理研究十分重要.对近期完成的区域重力测量数据开展了场源边缘检测和密度界面反演等处理, 获得了延庆盆地新生界基底形态及断裂展布特征.同时收集钻孔测温和热导率资料计算了17眼钻孔的大地热流, 分析了热流异常及其构造成因, 得到结论如下: (1)延庆盆地的基底形态为"一凸四凹一单斜", 即东五里营凸起、姚家营凹陷、张老营凹陷、田宋营凹陷、卓家营凹陷、康庄—沈家营单斜带.延庆盆地由2条NE向断裂控制, 6条近SN向断裂连通山区补给区并切割NE向断裂, 构成纵横交错的浅部断层网络.(2)延庆盆地大地热流平均值为65.8±13.0 mW·m-2, 略低于渤海湾盆地热流均值, 相对高热流区有两处, 一是康庄—沈家营断裂和靳家堡断裂交汇区, 二是西卓家营凹陷和东五里营凸起之间的过渡带.(3)延庆盆地地表热流异常主要与蓟县系碳酸盐岩高热导率地层分布及其厚度变化、多体系浅部断裂组合控制地下水热活动促使热流再分配有关, 盆地北缘佛峪口—黄柏寺断裂发育和燕山期花岗岩侵入影响较小.     

沁水盆地大地热流与地温场特征

分析了20口井的温度数据和39个岩石样品的热导率数据,计算了20个大地热流值.结果表明：沁水盆地具有偏高的大地热流背景,现今热流变化于44.8～101.8 mW/m2之间,平均62.7±15.2 mW/m2,现今地温梯度介于20.9～47.6 ℃/km之间,平均地温梯度28.2±10.3 ℃/km. 热流的分布与本区上、下主煤层含气量的分布特征相似,在一定程度上反映了现代热流继承了煤层气生气期的古地热背景.