Geoheritage significance of three Pleistocene formations recording a succession of climates and sea levels on the Yalgorup Plain in southwestern Australia

The Yalgorup Plain of southwestern Australia is underlain by two limestone formations and a linear quartz-sand formation containing limestone lenses. These limestones record carbonate deposition in seagrass banks during the Pleistocene; they are capped either by a prograding beach-ridge system of small cuspate forelands or a quartz-rich shore-parallel coastal barrier. The cuspate forelands formed behind protective offshore limestone reefs within a given Pleistocene wind-and-wave field, while the quartz-rich coastal dune barrier formed under enhanced swell conditions. These formations record three different Pleistocene interglacial depositional events, separated by unconformities, each linked to a distinct climate and mean sea level. Foraminiferal assemblages within the two limestones and within the limestone lenses of the quartz-sand formation faithfully record changes in minimum seawater temperature, reflecting these changes in climate. They indicate a cycle of warm–cool–warm water accumulation of carbonates. Such a record of both climate and sea level history for southwestern Australia is unique, contributing greatly to the Pleistocene coastal sedimentary history of limestones within southwestern Australia. These formations occur within the globally unique setting of Western Australia and are conserved within a National Park and represent an outstanding record of Quaternary coastal geomorphic development in terms of both carbonate and siliciclastic sedimentation linked to both climate and sea level changes. Given their array of lithofacies, environmental setting, sea level and climate changes, as well as their biostratigraphy reflecting these changes, these formations form a sedimentary ‘package’ that is of global geoheritage significance, with many of its inherent geological features also of global to national geoheritage significance.     

Origin of yellow sand from Tamala Limestone on the Swan Coastal Plain,Western Australia

There has been considerable debate concerning the origin of the Spearwood Dunes on the Swan Coastal Plain in Western Australia. In general, it is believed that the Spearwood Dunes are a complex of calcareous coastal dunes deposited during the Quaternary and now consist of an aeolianite core (the Tamala Limestone) plus tracts of surficial residual sand from dissolution thereof. However, in the mid‐seventies a counter view was presented suggesting that the sand was not residual but was transported by aeolian processes from inland sources. At 11 sites on the Swan Coastal Plain a combination of grainsize analysis and heavy‐mineral analysis was used to demonstrate that the sand of the Spearwood Dunes has evolved as a result of in situ weathering of the underlying Tamala Limestone. This supports previous work on the Swan Coastal Plain and other sandplains in Western Australia, suggesting that there has been very little long‐range aeolian transport of sands during the Late Pleistocene.     

Modelling water-table depth in a primary aquifer to identify potential wetland hydrogeomorphic settings on the northern Maputaland Coastal Plain,KwaZulu-Natal,South Africa

The primary aquifer on the Maputaland Coastal Plain in northern KwaZulu-Natal, South Africa, is the principal source of water for rivers, lakes and most of the wetlands in dry periods, and is recharged by these systems in wet periods. Modelling hydrologic conditions that control regional water-table depth can provide insight into the spatial patterns of wetland occurrence and of the persistence of wet conditions that control their character. This project used a groundwater model (MODFLOW) to simulate 10-year water-table fluctuations on the Maputaland Coastal Plain from January 2000 to December 2010, to contrast the conditions between wet and dry years. Remote sensing imagery was used to map “permanent” and “temporary” wetlands in dry and wet years to evaluate the effectiveness of identifying the suitable conditions for their formation using numerical modelling techniques. The results confirm that topography plays an important role on a sub-regional and local level to support wetland formation. The wetlands’ extent and distribution are directly associated with the spatial and temporal variations of the water table in relation to the topographical profile. Groundwater discharge zones in the lowland (1–50 masl) areas support more permanent wetlands with dominantly peat or high organic soil substrates, including swamp forest and most of the permanent open water areas. Most temporary wetlands associated with low-percentage clay occurrence are through-flow low-lying interdune systems characterised by regional fluctuation of the water table, while other temporary wetlands are perched or partially perched. The latter requires a more sophisticated saturated-unsaturated modelling approach.     

湿地水文学研究进展

水文过程在湿地形成、发育、演替直至消亡全过程中起重要作用.降水截流、径流和蒸散作用是湿地 大气界面水文过程研究的热点和重点,开发的模型较多但尚需进一步检验和完善.片流和明渠流是湿地主要地表径流,其中片流受地形坡度等因素影响而难以精确计算.湿地的地下水文系统对季节性积水湿地尤为重要,但是关于泥炭沼泽的垂向水力联系尚需进一步研究.可持续的湿地水文管理必须将人类活动和气候变化这两个因素纳入湿地综合水文模型,然而目前除少数几个综合模型外,大多数的湿地水文模型并非如此.加强湿地水文观测、多手段多技术相结合和开发综合湿地水文模型应是今后湿地水文学研究的主流.     

近50年来我国北方典型区域地下水演化特征

文章在总结中国北方地下水最新调查成果的基础上,选择西北内陆盆地、华北平原和松嫩平原为典型区,对近50年来区域地下水系统的演变特征及其影响因素进行探讨。研究发现: 我国北方盆地和平原地下水系统演化具有渐变性和突变性特征,但在不同地区存在着差异,区域地下水系统已经变得脆弱,地下水资源可持续利用向不利的方向发展。地下水补给演变表现为山前平原地带的补给能力减弱,河道补给减弱或消失,中下游农业区地下水补给强度增大,总补给量呈现减小的趋势;  其中,西北内陆盆地下水补给的减少与上游水资源利用过度、渠系防渗程度提高有关;  而华北平原和松嫩平原地下水总补给量的减少与降雨量的减少和山区河流拦蓄水量的增加有关。伴随着补给模式的改变,地下水流场演变表现为普遍出现持续性的区域地下水位下降,西北干旱区表现为山前平原地下水位快速下降、泉流量减少、溢出带下移;  华北平原和松嫩平原表现为溢出带消失、水位降落漏斗形成并发展,区域地下水流被截断,形成以降落漏斗为中心的局部水流系统。地下水化学场变化主要表现为水化学类型变化、矿化度增大,污染组分增加。自西北内陆盆地至华北平原、松嫩平原,水化学变化强度明显增加,以华北平原和松嫩平原最为明显。本文在这些认识的基础上提出了应对气候变化与人类活动双重影响下地下水演变的适应性对策,为地下水资源可持续利用提供了理论依据。     

松嫩平原湿地演变及其驱动因素分析

湿地是生态系统的重要组成部分,在维系区域生态安全中扮演着重要角色.利用1975、2000和2018年的Landsat遥感影像数据,获取3期湿地解译数据,采用动态度分析、差异性分析、转移矩阵等方法对近50年来松嫩平原地区湿地的时空变化特征进行分析,为研究和保护松嫩平原地区湿地生态系统提供一定的理论依据.研究表明：湿地面积由1975年的20 189.81 km2上升至2018年的29 456.79 km2,整体上呈增加的趋势,具体表现为1975—2000年天然湿地的大幅度下降和2000—2018年人工湿地的大规模增加.分析认为：蓄水工程、河道防洪堤和湿地围垦是天然湿地减少的主要因素;降水量变化、气温上升、蒸发量增加是天然湿地变化的次要因素;受经济效益为中心理念驱动,水田改扩建增加是人工湿地增加的主要因素.     

Petrological features of the Santa Teresa Granitic Complex Southeastern Uruguay

The Santa Teresa Granitic Complex, located in the north-eastern region of the Rocha Department (Eastern Uruguay), is an epizonal Late-Brasiliano granite intruded in the low-grade metasedimentary sequence of the Rocha Group. Twelve different facies types, each with distinctive structural-petrographic features, were recognized during detailed mapping (1:50,000) of the central-eastern part of the granitic complex and form two magmatic suites. The Santa Teresa Calk-alkaline Suite is composed of mostly porphyritic 3a–3b granites with variable amounts of biotite, sphene, allanite, magnetite and microgranular enclaves and belongs to a middle to high potassium calk-alkaline series with high silica contents. In contrast, the Sierra de la Blanqueada Peraluminous Suite has a great variation of grain size, including 3a–3b granitic facies with variable content of muscovite, biotite, tourmaline, ilmenite and monazite. Zircon morphology was studied in both suites and also shows their calk-alkaline and peraluminous nature. The Santa Teresa Calk-alkaline Suite had a Late- to Post-orogenic setting whereas the Sierra de la Blanqueada Peraluminous Suite was formed during the crustal thickening related to a syn-collisional environment.     

Facies model of a sedimentary record for a Pantanal-like inland wetland

Despite recent advances in wetland studies, ancient wetland deposits are still not well documented, and their facies characteristics are poorly registered. Sedimentary facies and sequence stratigraphic analysis of the Miocene Yecua Formation (Chaco foreland basin, Central Andes, Bolivia) and their comparison to Pantanal-like modern wetlands provide an insight into their variability, suggesting a facies model for large inland wetlands that developed in a tropical–subtropical climate. Sedimentological features show that clastic, chemical and biological processes in these environments lead to distinguishable lithofacies variations. Six architectural elements are described: (i) muddy sublittoral (FA1); (ii) mixed siliciclastic–carbonate shoreface (FA2); (iii) sand-flat (FA3) and (iv) mud-flat (FA4) deposits; (iv) floodplain (FA5); and (vi) simple channel deposits (FA6). The succession is composed of shallowing-upward parasequences with different facies characteristics caused by climatically-driven changes of the water level over three orders of magnitude and cyclicity. These cyclic changes reflect a climatic control on the sedimentation. A palaeoclimatic interpretation suggests a generally warm, humid climate with marked rainfall regime changes. The aim of this article is to use this dataset to improve the understanding of depositional elements, lithologies and stratigraphy in tropical–subtropical large inland wetlands. The proposed criteria will help in recognizing inland wetland deposits in other sedimentary basins.     

Middle and Late Pennsylvanian cyclothems,American Midcontinent: Ice-age environmental changes and terrestrial biotic dynamics

The Pennsylvanian portion of the Late Paleozoic Ice Age was characterized by stratigraphic repetition of chemical and siliciclastic rocks in the equatorial regions of the Pangean interior. Known as “cyclothems”, these stratigraphic successions are a 10⁵ yr-record of glacial waxing and waning, superimposed on longer term, 10⁶ yr intervals of global warming and cooling and a still longer term trend of increasing equatorial aridity. During periods of maximum ice–minimum sea level, the interior craton was widely exposed. Epicontinental landscapes were initially subjected to dry subhumid climate when first exposed, as sea level fell, but transitioned to humid climates and widespread wetlands during maximum lowstands. During interglacials (ice-minima) seasonally dry vegetation predominated. The wetland and seasonally dry biomes were compositionally distinct and had different ecological and evolutionary dynamics.     

北京市重要地质遗迹资源及其形成

北京市重要地质遗迹主要包括基础地质类.地貌景观类和地质灾害遗迹3大类。本文叙述了重要地质遗迹资源的分布特征,并对地质遗迹形成演化做了介绍,为地质科研教学和地质旅游提供了基础资料。     

Lower Mississippi River tributaries: contributions to the collective science concerning the “Father of Waters”

The geological and geomorphic information preserved in the tributary valleys of the lower Mississippi River (LMR) contributes to our understanding of the lower valley's Quaternary geological history. Prominent Pleistocene terraces are preserved in the tributary valleys. Fisk first formulated his four terraces framework on the Red River. Caution needs to be followed in projecting the Red River terraces across the entire Lower Mississippi Valley (LMV). The tributary system cannot be assumed to operate in a synchronized fashion in response to changes in climate and base level. To compare the collective contribution of the tributaries of the LMR, the streams are described in terms of. (1) their characteristics, (2) geomorphic development, (3) process and response of the tributaries to and from the LMR, and (4) engineering investigations and implications. The characteristics of the tributaries are a direct function of their drainage basin size and geology. The tributary system drains portions of six physiographic provinces. Synoptically, the tributaries can be viewed as two groups: the eastern and western tributaries. All of the eastern tributaries are intra-regional, i.e., they drain only one physiographic province, the Coastal Plain, and therefore, have a restricted sediment source. Generally, the eastern tributaries are more numerous and shorter than the western tributaries. The longer western tributaries drain outside the Coastal Plain. The extra-regional nature of the western tributaries adds to the variability of discharge and sediment types. The sediment record of the tributaries reflects response to the trunk Mississippi. During glacial outwash flushes, many of the tributaries were alluvially drowned, producing alluvial cones expressed as flattened longitudinal profiles. More recently, a number of tributaries in the state of Mississippi have experienced episodes of accelerated channel erosion. The effects of navigation and flood control modification of the Mississippi River on the tributaries have not been fully studied. Therefore, fluvial geomorphic research in the tributaries is essential to understanding ways to mitigate the adverse effects of river engineering, thereby designing engineering works in balance with the alluvial architecture and processes of the stream system.     

Responses of groundwater system to water development in northern China

The increased demands on water resources in northern China have had a significant impact on groundwater systems in the last three to four decades, including reductions in groundwater recharge capacity and overall water quality. These changes limit the potential for groundwater uses in this area. This paper discusses the issues surrounding groundwater system use in the eight basins of northern China as water resources have been developed. The results demonstrate that the recharge zone has shifted from the piedmont to the agricultural area, and that the total recharge rate in the basins tended to decrease. This decrease in arid inland basins was mainly caused by both the excessive use of water in the watershed area and irrigated channel anti-seepage. In semi-arid basins, the decrease observed in the groundwater recharge rate is related to an overall reduction in precipitation and increasing river impoundment. In addition, intensive exploitation of groundwater resources has resulted in disturbances to the groundwater flow regime in arid and semi-arid inland basins. Arid inland basins demonstrated fast falling groundwater levels in the piedmont plains resulting in declines of spring flow rates and movement of spring sites to lower locations. In the semi-arid basins, i.e. the North China Plain and the Song-nen Plain, groundwater depression cones developed and intersected regional groundwater flow. The semi-arid basins of the North China Plain and the Song-nen Plain have experienced significant hydrochemical evolution of groundwater characterized by changing water type including increase of TDS and pollutants.     

松嫩平原湿地分布变化与影响因素分析

近20年来松嫩平原生态环境发生了巨大变化,湿地退化加剧是生态环境变化的重要表现之一.利用1986年（TM）和2001年（ETM）卫星遥感影像数据和RS-GIS集成技术,对松嫩平原湿地的现状和变化趋势进行了量化分析.结果表明,在过去的15年中,松嫩平原湿地面积减少了658 042 hm²,减少了38.81%.平均每年减少43 869 hm²,年均减少速率2.59%.其中地表水体减少127 429 hm²,减少了22.81%;沼泽减少530 612 hm²,减少了46.67%.降水减少,蒸发加大,水资源开发过大以及过度放牧、围垦湿地是湿地退化的主要原因.     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.