Holocene coastal evolution and uplift mechanisms of the northeastern Raukumara Peninsula,North Island,New Zealand

The coastal geomorphology of the northeastern Raukumara Peninsula, New Zealand, is examined with the aim of determining the mechanisms of Holocene coastal uplift. Elevation and coverbed stratigraphic data from previously interpreted coseismic marine terraces at Horoera and Waipapa indicate that, despite the surface morphology, there is no evidence that these terraces are of marine or coseismic origin. Early Holocene transgressive marine deposits at Hicks Bay indicate significant differences between the thickness of preserved intertidal infill sediments and the amount of space created by eustatic sea level rise, therefore uplift did occur during early Holocene evolution of the estuary. The palaeoecology and stratigraphy of the sequence shows no evidence of sudden land elevation changes. Beach ridge sequences at Te Araroa slope gradually toward the present day coast with no evidence of coseismic steps. The evolution of the beach ridges was probably controlled by sediment supply in the context of a background continuous uplift rate. No individual dataset uniquely resolves the uplift mechanism. However, from the integration of all evidence we conclude that Holocene coastal uplift of this region has been driven by a gradual, aseismic mechanism. An important implication of this is that tectonic uplift mechanisms do vary along the East Coast of the North Island. This contrasts with conclusions of previous studies, which have inferred Holocene coastal uplift along the length of the margin was achieved by coseismic events. This is the first global example of aseismic processes accommodating uplift at rates of >1 mm yr⁻¹ adjacent to a subduction zone and it provides a valuable comparison to subduction zones dominated by great earthquakes.     

Holocene coastal change at Luce Bay,South West Scotland

Coastal change during the Mid- to Late Holocene at Luce Bay, South West Scotland, is examined using morphological, stratigraphic and biostratigraphical techniques supported by radiocarbon dating. Deglaciation left extensive sediments, providing a source for depositional coastal landforms. Glacio-isostatic uplift resulted in the registration of evidence for former relative sea levels (RSLs), which support the pattern of Holocene RSL change for the northern Irish Sea as determined by shoreline-based Gaussian trend surface models. The rate of RSL rise was rapid from before ca. 8600 to ca. 7800 cal a bp , but then slowed, changing by <3 m over the next 3000 years, a pattern reflected in the convergence of shorelines predicted in the models. By ca. 4400 cal a bp RSL was falling towards present levels. As these changes were taking place, coastal barriers developed and dunes formed across them. In the West of the Bay, a lagoon forming to landward of the barriers and dunes acted as a sediment sink for dune sand. Changes in the coastal landscape influenced the occupation of the area by early human societies. This study illustrates the value of combining an understanding of process geomorphology, RSL and archaeology in studies of coastal change.     

河流输沙与中国海岸线变化

我国沿海地区构造升降使入海河流沉积物分布不均，９５％于构造下降地区入海，构造上升区接纳的河流泥沙不足５％，入海河流泥沙分布不均是我国海岸基本类型和海岸线变化差别的主要原因。在此基础上讨论了最大海侵的范围及时间，海岸线变化的趋势、速度和周期以及河流输沙对未来海岸线变化预测的影响。     

中国海岸带地质资源与环境评价研究

海岸带是中国社会经济发展的前沿地带,人口密度最大、城镇化程度最高,在中国海洋强国战略中发挥重要的支撑作用,同时也是中国资源环境压力最大的区域。本文在全面分析近20年来中国海岸带地质资源环境调查成果的基础上,系统梳理了海岸带地区地质资源环境优势和存在的地质环境问题。中国海岸带地质资源环境优势突出,为绿色发展提供了良好条件,重要地质资源环境优势包括:1.2×10~4km~2滩涂后备土地资源可适度开发,以缓解海岸带建设用地紧张局面;2.8×10~4km~2绿色富硒土地和4.1×10~5km~2绿色渔场,适宜发展绿色特色农业和建设海洋牧场;浅层地温能和地热水年可开采量折合标准煤4.2×10~8t,对改善能源结构、减少大气污染有重要作用;5.8×10~4km~2滨海湿地和134处国家级和世界级地质遗迹资源,为海岸带生态文明建设提供了条件;90%的陆域适宜城镇和重大工程规划建设,地下空间开发条件较好,为海岸带地质安全提供了保障。存在的主要环境问题包括:海岸带局部存在活动断裂、地面沉降、地面塌陷、海岸侵蚀淤积、风暴潮等重大地质问题,对部分城市与重要基础设施形成威胁,局部地区水、土污染及海水入侵严重,需要高度重视。建议加大海岸带多学科综合地质调查,构建多要素、多圈层、多维度地质模型,查明自然灾害发生的规律和原因,减轻对人民生命财产造成的损失。     

Origin,geomorphology and geoheritage potential of Australia’s longest coastal cliff lines

Abstract

Two spectacular cliff lines occur along Australia’s south and west coasts: the Great Southern Scarp (new name) and the Zuytdorp Cliffs. Detailed measurements of their length show that they are exceptionally long and unusually continuous. The Great Southern Scarp is the southern edge of the Nullarbor Plain’s Bunda Plateau; it is cut into shallow marine sediments and extends for 820?km. Once a continuous sea-cliff, local uplift has isolated two sections from the ocean, so it now comprises the Bunda Cliffs (210?km of coastal cliff, 180?km of which is uninterrupted cliff line), Hampton Range (inland; 300?km), Baxter Cliffs (160?km of coastal cliff) and Wylie Scarp (inland; 160?km). The Zuytdorp Cliffs are coastal cliffs cut into eolianite, and extend for 210?km with an uninterrupted section of 120?km. The length of the Great Southern Scarp and the Zuytdorp Cliffs results from an unusual combination of circumstances. They are both composed of poorly jointed, relatively homogenous biogenic calcarenites, presented to high-energy ocean waves by regional uplift. The carbonates are sufficiently well cemented to maintain a steep vertical cliff face, but susceptible to disintegration under direct wave attack. Cliff retreat has been fairly uniform because of the broad spatial scale of both lithology and erosion. The arid climate, absence of nearby non-karstic catchments and karstic nature of the cliffs’ hinterlands has discouraged integrated drainage development, so no significant fluvial systems dissect the cliffs; this is a key factor in cliff edge preservation. In the case of the Great Southern Scarp, these processes have formed the longest continuous cliff line in Australia and probably the world. Referenced against criteria from Australia’s National Heritage List, the cliffs have potentially international/national levels of significance for the rarity of their scale, their demonstration of landscape evolution, and their spectacular beauty.

1. KEY POINTS

2. Australia’s longest coastal cliffs, the Bunda (SA) and Zuytdorp (WA) cliffs, are equal in length (210?km, within defined confidence levels).

3. The Bunda Cliffs are part of the Great Southern Scarp (new name), an 820 km-long feature of the Nullarbor Plain that also includes the coastal Baxter Cliffs (160?km in length) and two paleocoastal scarps.

4. The unusual continuity of the cliff lines results from a landscape history specific to the Australian continent, and the Great Southern Scarp is likely to be unusual on a global scale.

5. The Great Southern Scarp and the Zuytdorp Cliffs have potentially national and/or international levels significance for geoheritage values in the criteria of events and processes, rarity and aesthetics.

     

Application of226Ra,228Ra,223Ra, and224Ra in coastal waters to assessing coastal mixing rates and groundwater discharge to oceans

The fate of dissolved material delivered to the coastal ocean depends on its reactivity and the rate at which it is mixed offshore. To measure the rate of exchange of coastal waters, we employ two short-lived radium isotopes,²²³Ra and²²⁴Ra. Along the coast of South Carolina, shore-perpendicular profiles of²²³Ra and²²⁴Ra in surface waters show consistent gradients which may be modeled to yield eddy diffusion coefficients of 350–540 m²s⁻¹. Coupling the exchange rate with offshore concentration gradients yields estimates of offshore fluxes of dissolved materials. For systems in steady state, the offshore fluxes must be balanced by new inputs from rivers, groundwater, sewers or other sources. Two tracers that show promise in evaluating groundwater input are barium and²²⁶Ra. These tracers have high relative concentrations in the fluids and low-reactivity in the coastal ocean. Applying the eddy diffusion coefficients to the offshore gradient of²²⁶Ra concentration provides an estimate of the offshore flux of²²⁶Ra. Measuring the concentrations of²²⁶Ra in subsurface fluids provides an estimate of the fluid flux necessary to provide the²²⁶Ra. These estimates indicate that the volume of groundwater required to support these fluxes is of the order of 40% of the surface water flow.     

Landscape evolution of the Blue Mountains revealed by longitudinal river profiles and Cenozoic basalts and gravels

Abstract

For the past 200?years, there have been numerous investigations and much speculation concerning the formation of the dramatic valleys of the Blue Mountains of NSW. In this paper, further evidence for the uplift and erosional history of the Blue Mountains is obtained from longitudinal river profiles, detailed mapping of the Rickabys Creek Gravel on the Lapstone Structural Complex and consideration of the topographical position of Miocene basalts. Knickpoints on the main rivers flowing east from the Great Dividing Range are identified and interpreted to be due to uplift events linked to the northward movement of the Australian continent over mantle inhomogeneities. At the Lapstone Structural Complex on the eastern range front, the occurrence of the Rickabys Creek Gravel and the nature of the over-steepened reaches on the rivers and streams crossing the Complex, suggest a more recent ongoing phase of uplift and antecedent river erosion. The Miocene basalts provide evidence of this landscape 20–15?Ma. Their locations with respect to the current rivers and ridges are interpreted to show additional evidence for recent uplift that has resulted in the formation of the Lapstone Structural Complex. It is suggested that this uplift commenced 10–5?Ma when the contemporary compressive stress field was established.

• KEY POINTS

• Longitudinal profiles for major rivers in the Blue Mountains are consistent with a model of initial Cretaceous uplift followed by further Cenozoic uplift associated with dynamic topography.

• Mapping of Rickabys Creek Gravel within the Lapstone Structural Complex suggests the presence of antecedent rivers.

• Within the Lapstone Structural Complex, stream profiles, gravels and nearby outcrops of Miocene basalts are interpreted to indicate a third phase of uplift, possibly since 10?Ma.

     

Geomorphological,stratigraphic and geochronological evidence of fast Pleistocene coastal uplift in the westernmost part of the Corinth Gulf Rift (Greece)

Rapid extension and active normal faulting in the western extremity of the Corinth Gulf are accompanied by fast coastal uplift. We investigate Pleistocene uplift west of Aigion, by attempting to date remains of marine terraces and sedimentary sequences by calcareous nannoplankton and U‐series analyses. Net uplift initiated recently, due to abandonment of an older rift‐bounding fault zone and increase in activity on the presently active, coastal fault zone. This change apparently coincides with an abrupt slow down (or, termination) of secondary fault block tilting within the broader hangingwall block of the older zone, indicated by an angular unconformity that dates in the early part of MIS10 (∼390–350 ka BP, preferably, in the earlier part of this period). Net uplift driven by the coastal zone resulted in the formation of MIS9c (330 ka) and younger terraces. The formation of the unconformity and the initiation of net uplift coincide temporally with a ∼300–400 ka unconformity recognized by recent studies in a wide area offshore Aigion i.e. they could be part of an evolutionary event that affected the entire western part of the Corinth Rift or, a large area therein. Uplift rate estimates at four locations are discussed with reference to the morphotectonic context of differential uplift of secondary fault blocks, and the context of possible increase in uplift rate with time. The most reliable and most useful estimate for uplift rate at the longitude of the studied transect is 1.74–1.85 mm/year (time‐averaged estimate for the last ∼240 ka, based on calcareous nannoplankton and sequence‐stratigraphic interpretation). Copyright © 2009 John Wiley & Sons, Ltd.     

近20年来长江三角洲海岸带典型区土地利用变化与生态环境效应研究

【研究目的】近20年来,长江三角洲海岸带地区土地类型结构发生显著转化,海岸带开发与保护的矛盾凸显。本文旨在开展长江三角洲海岸带典型区土地利用变化与生态环境效应研究,为海岸带地区的土地资源可持续利用、海岸带环境保护提供科学依据。【研究方法】利用美国Landsat卫星系列遥感影像和中国资源卫星系列遥感影像,采用自动监督分类并结合目视解译,获取了研究区1995—2015年共5期土地利用分类数据,分析土地利用变化特征和趋势,探讨长江三角洲海岸带典型区城镇发展、围填海时空变化及生态环境效应。【研究结果】长江三角洲海岸带典型区（南通、上海、嘉兴、宁波和舟山）1995年至2015年,土地利用变化明显,耕地大幅度减少,比例从1995年的68.8%降为2015年的55.7%;城镇建设用地迅速扩张,年平均增加192.8 km²。【结论】在快速城市化过程中,人口、单位面积能源消耗等快速增加,环境问题凸显,大量的耕地转为建设用地,围填海使滨海湿地面积快速减小和消失,导致CO₂和污染物释放与吸收严重失衡,海洋环境受流域和沿海城镇化建设的影响明显,长江口及邻近海域近20年来赤潮频发,研究区陆域和海洋环境压力增加。创新点：选取长江三角洲海岸带典型区,首次以1995—2015年5期序列遥感影像数据为基础,采用空间叠加分析方法,着重分析了建设用地和围填海区域的时空演化特征;以人类活动为主线,综合多种海洋环境指标,分析快速城市化进程中,建设用地和围填海导致的生态环境效应。     

Uplift rate and landscape development in southwest Fiordland, New Zealand, determined using Be and Al exposure dating of marine terraces

We demonstrate that cosmogenic nuclide surface exposure dating can be used to provide the first well-constrained age for a Fiordland bedrock surface that was created by coastal erosion and has since been uplifted. Tight clustering of ¹⁰Be and ²⁶Al apparent exposure ages between 102-119 kyr on a terrace with strandline at 65 ± 8 m gives a last interglacial age of terrace formation of 130-120 ka, and an uplift rate of 0.52 ± 0.08 mm/yr. Apparent exposure ages from a higher (92-130 m), more incised region of remnant coastal morphology fall in the range 53-111 kyr. The anomalously low ages and large variance demonstrate that weathering and fluvial or rockfall erosion rates are too extreme at the higher sites to determine an age of coastal erosion. Sea level samples have apparent exposure ages in the range 2-11 kyr, with an uncertainty of about 3 kyr. This is consistent with surface exposure during the present sea level high-stand, indicates minimal inheritance of ancient cosmogenic nuclides, and is in accord with geomorphic arguments. Mean ²⁶Al/¹⁰Be ratios of 6.6 for each sample set is consistent with the actively exhuming late Quaternary tectonic setting. Large boulders and gently convex rocky outcrops formed during coastal erosion preserve surfaces that are least modified during later uplift, and are hence the best sites for determining the age of coastal erosion.     

Provenance and sediment characteristics of contemporary gravel deposits at Sellicks Beach,eastern shore of Gulf St Vincent,South Australia

Sellicks Beach, located on the eastern shore of Gulf St Vincent, South Australia, is subject to wave-dominated processes and northward longshore transport. During winter, when wave energy is typically vigorous, gravel deposits are exposed across most of the beach, and three step-like berms are well developed. Sand is restricted to a narrow strip that is exposed only at low tide. In contrast, during summer, when wave energy is generally moderate to low, much of the gravel is covered by a thin veneer of sand and only the high berm, on the landward edge of the beach, remains as an obvious feature. Steeply dipping Neoproterozoic to Cambrian strata that outcrop strongly across Sellicks Hill are the original source rocks for the beach gravel; distinctive sedimentary textures, structures and fossils in the cobble-size clasts can be confidently matched with those of the provenance rocks. Much of the sediment entered the modern beach environment as a consequence of coastal erosion of transitional alluvial fan sediments. The oldest alluvial fan sediments are of late Pliocene to earliest Pleistocene age. Mount Terrible Gully provides a conduit for the input of fluvial sediment at the mouth of Cactus Canyon, where clasts as large as boulders accumulate across the beach. Sellicks Beach gravels are subject to longshore transport northwards. Relatively softer clasts, such as those derived from the Heatherdale Shale, are rare beyond Cactus Canyon. In contrast, quartzite clasts are more abundant towards the north. This lithological differentiation is attributed to preferential survivorship of clasts that are physically harder and chemically less reactive. The change in the shapes of clasts northwards, from predominately shingle-like ‘very platy’ and ‘very bladed’ at Cactus Canyon, to more ‘compact’ towards the boat ramp, is in accord with the more massive fabric of the surviving quartzite clasts. At Sellicks Beach, preservation of uplifted, coarse gravels, with entire and comminuted marine molluscan shells, of last interglacial age, provides evidence of neotectonism. At the landward margin of the beach, imbricated gravels in which pore spaces have been infilled with mud, and which show no evidence of modern coastal erosion, may provide evidence of continuing uplift during the recent Holocene. The geological setting, geomorphic framework and modern sedimentary regime at Sellicks Beach combine to provide an exceptionally useful outdoor laboratory for education in field geology.     

Effects of differential tectonic uplift on Late Quaternary coral reef diagenesis,Huon Peninsula,Papua New Guinea

Mineralogical, petrological and geochemical analyses of corals and associated skeletal limestones taken from three transects across the Late Quaternary raised coral reefs of the Huon Peninsula, Papua New Guinea, show that tectonic uplift can be related to the degree of subaerial diagenesis of the reefs. Where the uplift rate is high, Pleistocene corals frequently retain their aragonite mineralogy, even though the annual rainfall is relatively high. In contrast, similar age corals from low‐uplift areas are consistently altered neomorphically to calcite. The transformation of reef skeletal limestones shows a similar, but less pronounced, trend to the corals. Chemical analysis shows that the neomorphic calcite crystals of coral skeletons from the low‐uplift areas have relatively higher Sr and Mg concentrations, compared with those in high‐uplift areas. This may indicate that neomorphism of corals in the low‐uplift terraces takes place at a relatively higher rate and an earlier stage than that in the high‐uplift areas. The pattern of diagenesis of the Huon reefs can be explained by the effects of tectonic uplift on the regional hydrological regime. First, lower uplift rates allow a raised reef or any part of it to remain in the meteoric phreatic zone for a relatively long time. Second, river gorge slopes from low‐uplift regions have lower gradients and reef terraces in these areas have more extensive raised lagoon depressions than in high‐uplift areas. Thus, there is less runoff and consequently more extensive vadose percolation in the former areas. Third, the resulting low‐relief topography in low‐uplift areas prompts formation of soils on the terraces, and further increases the ability of interaction between coral reefs and formation water.     

Detection of large,Holocene earthquakes using diatom analysis of coastal sedimentary sequences,Wellington, New Zealand

Paleoenvironmental reconstructions of three coastal waterbodies in Wellington, New Zealand, reveal that sites were isolated from the sea within the last 7500 years through coseismic uplift and barrier growth. Evidence for coseismic uplift consists of distinct transitions in diatom assemblages representing large changes in relative sea-level or water-table level, commonly in association with sedimentological evidence for catchment disturbance or marine influx. Transitions are abrupt, laterally extensive and synchronous within each waterbody. Amount of change across transition horizons is assessed using quantitative estimates of paleosalinity and waterbody type as proxies for relative sea-level change. Seven transitions involve large paleoenvironmental changes and provide evidence for earthquakes occurring at approximately 5100, 3200 (recorded at two sites), 2300 (recorded at two sites), 1000 cal years BP and 1855 AD. Five other transitions involve smaller paleoenvironmental changes and are considered to be consistent with effects of earthquakes but do not provide independent evidence for earthquake occurrence. These smaller transitions occur at approximately 6800, 3600, 2200, 1000 (coincident with a large transition) and 500 cal years BP. The data refine ages and provide information about the extent and effects of past large earthquakes in the region. These are the first paleoecologically derived earthquake signatures for Wellington and they contribute to the sparse collection worldwide of off-fault sedimentary earthquake records for predominantly strike-slip faults.     

Climate shifts and coastal changes in a geological perspective. A contribution to integrated coastal zone management

This Special Issue deals with the impact of climate change on western European coastal systems. Notwithstanding the inherent problems of studying geological data in terms of climate shifts, the results show that on the meso- and the macroscale of time, climatic forcing is a major drive for coastal change. However, its impact is largely influenced by other factors. Sediment availability plays a dominant role in the evolution of coastal systems and it can be considered one of the most important thresholds at the land-ocean interface. Sea-level changes are expected to have a significant impact on most European coasts. There is particular concern for the tidally influenced flats and marshes, and for those coastal areas known to have already a net sediment deficit and to be threatened by erosion. Areas where isostatic uplift has countered sea-level rise until now, are expected to become subject to coastal erosion in the near future under an accelerated sea-level rise scenario. The sensitivity and vulnerability of coastal systems to climate shifts is shown to be largely controlled by storm magnitude and fetch. A particular case of vulnerability is the impact of tsunamis. Finally, the consequences of human interference have been demonstrated in many cases. The implementation of geoscientific studies for rational, comprehensive and cost-effective strategies on a regional or national level of integrated coastal zone management is reviewed.     

Control factors on turbidite sedimentation in a deep-sea trench setting. – The example of the Schlieren Flysch (Upper Maastrichtian-Lower Eocene,Central Switzerland)

Abstract

Deep-sea turbidite sedimentation in convergent margin settings generally is controlled by tectonic uplift, climate and eustatic sea-level variations. The rate of tectonic uplift governs the relief of the source area and the position of the base level (coinciding with sea-level), climate influences the rate and style of weathering and continental runoff and eustatic seal-level additionally shifts the base level, functioning with the concurrently working tectonic movements. Thus, these factors primarly determine the availability of sediment (yield and nature of material and the site of intermittent storage) at the basin margin which is unlocked periodically to flow downslope to the basin.

This paper attempts to decipher quantitatively the importance of the individual factors in the Late Maastrichtian to Early Eocene Schieren Flysch Croup. The flysch was deposited in a moderately converging remnant oceanic trench basin. Mean parameters are calculated on the basis of formations and the duration of nannofossil zones comprised in. For transposing these zone into absolute age intervals the problem of inconsistent durations in current time scales had to be solved by a best-fit approach. Frequencies and periodicities of turbidite events, decompacted and compacted sedimentation rates (the latter are considered as apparent denudation rates) are calculated to reveal the dynamics of sedimentation. Climatic evidence is deduced from clay mineralogy. Changing uplift rates in the drainage area are indirectly interpreted from back-stripped tectonic subsisdence rates in the basin.

The obtained data point to an immediate control of sub-duction-Iinked tectonic uplift in the bordering drainage and shelf area on turbidite sedimentation, as frequency and thickness of the turbidite events are closely correlated with the increasing tectonic subsisdence in the basin (assumed to match the rate of subduction and underplating). This general trend is modified by the temporary migration of the oceanic hinge zone towards the trench causing periodically the starvation of outer portions of the basin at the transition from Early to Late Paleocene and Late Paleocene to Eocene. Regional climatic trends additionnaly rule the turbidite facies development and apparent denudation rates. In the upper part of Early Eocene series high rate mud dominated sediments correlate with warm/humid conditions and in Late Paleocene deposits low rate sandy sediments coincide with cool ones. During the Late Paleocene period the global 2nd-order sea-level lowering probably may be responsible for the by-passing of the shelf by the coarse grained sediments.     

Evidence for 17th-century tsunamis generated on the Kuril–Kamchatka subduction zone, Lake Tokotan, Hokkaido, Japan

In the seventeenth century, two tsunamis that were generated by earthquakes on the Kuril–Kamchatka subduction zone inundated the eastern coast of Hokkaido, northern Japan. Stratigraphic evidence for these two tsunamis and related land-level change in coastal Hokkaido consists of two landward-thinning sand layers in the sediments of Lake Tokotan, a coastal lagoon on the Hokkaido coast. The marine origin of these sand layers is indicated by the presence of brackish–marine diatoms. The rarity and high degree of fragmentation of diatom valves suggests that the sands were transported in a short time over a considerable distance. Tsunamis at this site were probably generated by great earthquakes along the Kuril–Kamchatka Trench. Volcanic ash deposits lying just above the sands suggest that tsunamis occurred in the late 17th century. Tsunamis during the historic period are not recorded in Lake Tokotan, which suggests that the sand layers were deposited by tsunamis substantially larger than historic tsunamis.     

Late Pleistocene records of littoral processes at the Tyrrhenian Coast (Central Italy): depositional environments and luminescence chronology

Two cliff-sites on the Tyrrhenian coast of central Italy have been investigated in order to investigate late Pleistocene depositional environments by microfacies analysis and chronostratigraphy by luminescence age estimations. Both sections cover the period from the Last Interglacial to the end of the Last Glaciation. In the Buca dei Corvi site an increasing rate of uplift is recognised, which is responsible for significant environmental change and formation of the modern coastal fault scarp at around 9 ka. In the Golfo di Baratti site the vertical succession of three marine horizons, previously recognised by Cortemiglia et al., (1983), is attributed to the OIS stages ⩾5c, 5a and 3 respectively. This cliff-section is affected by NNE–SSW orientated normal faults, confirming that extentional structural processes are still active. The coastal deposit of Stage 3, today located at 7 m a.s.l., suggests abnormal high uplift rate if the position of the palaeo-shoreline was assumed at −40 to −50 m. Both central Mediterranean coastal records strongly suggest that the eustatic sea-level has dropped to a smaller amount than that of the open oceans.     

沿海地区复杂地层抗拔桩在深基坑中的试桩实例

通过沿海地区复杂地层中抗拔桩试桩实例,介绍了抗拔试验桩试验参数与方法以及深基坑中的抗拔桩施工技术：填石夹填土层成孔技术、桩端岩心取样技术与桩基清孔技术。试验表明,抗拔试验参数较为可靠且能满足结构设计的抗拔要求,为抗拔桩在深基坑中的应用研究提供了数据支撑。     

Thermotectonic evolution of a rifted continental margin: fission track evidence from the Kangerlussuaq area, SE Greenland

Fission track analyses of apatites from sediments, Precambrian gneisses and Caledonian to Tertiary intrusive rocks from the Kangerlussuaq region reveal its post-Caledonian thermotectonic history. Inland the history involves cooling to temperatures within the high temperature part of the apatite annealing interval and slow cooling (or reheating) continued in Cretaceous times through this interval. Apatites from coastal areas between Kangerlussuaq and Tasiilaq reveal only Tertiary cooling. In Tertiary times cooling accelerated after the main intrusive phase in the Tertiary. The evolution is taken as evidence for a general uplift/erosion since Caledonian times probably disturbed by basin formation and sedimentation and reheating due to magmatic activity. Thermal subsidence of the rift shoulders following the opening of the adjacent oceanic basin is not indicated. Annealing patterns inland of the plume centre in the Kangerlussuaq provide no evidence for the earlier movement of the plume from a westerly direction.     

安徽长江经济带地热资源赋存特征及潜力评价

【研究目的】安徽长江经济带地热资源储量丰富,未来开发利用前景好,对该区域进行地热资源评价可为安徽省能源结构优化及地热资源可持续开发利用提供科学依据。【研究方法】在分析研究区地质构造、地层岩性、地热流体水化学类型等地质与水文地质条件的基础上,揭示了安徽长江经济带地热资源概况及分布特征,探讨了隆起山地对流型和沉积盆地传导型地热资源的赋存特征,并对其储量及开发利用潜力进行评价。【研究结果】安徽长江经济带地热资源热储主要赋存在巢湖—和县基岩隆起区、大别山隆起区、沿江基岩隆起区、江南隆起等隆起山地及定远断陷盆地、肥东断陷盆地、霍山—九井盆地、庐枞断陷盆地、安庆断陷盆地、宣城断陷盆地等沉积盆地。前者隆起区热储类型为带状,岩性以断裂破碎带中花岗岩为主,后者断陷盆地热储类型为层状及层状兼带状,岩性以砂岩和碳酸盐岩为主。带内热储主要为偏硅酸·氟热矿水,隆起山地型地热流体水化学类型主要为SO₄、HCO₃型水,沉积盆地型地热流体水化学类型主要为HCO₃型水。通过潜力评价可知,隆起山地型地热资源潜力较小,且处于开发利用状态的地热田基本处于超采状态;沉积盆地型地热资源潜力相对较大,其中潜力大、中和小的盆地分别有4处、6处和10处。【结论】安徽长江经济带区域内地热资源潜力分布不均,地热资源需要分区规划利用,并且需要考虑高氟、高矿化度热矿水利用造成的地表水环境污染。