Holocene alluvial stratigraphy in the upper Susquehanna River Basin, New York

Two alluvial terraces and the present flood plain were studied at two locations along the Susquehanna and Unadilla Rivers in south-central New York state. They have formed since deglaciation and incision of the stream channels into the valley train deposits. The higher terrace has noncumulative soil profiles with well-developed color B horizons predominantly of silt loam and very fine sandy loam. The terrace is weathered to a degree similar to nearby glacial outwash terraces that have caps of similarly textured sediments. Incision that produced the terrace occurred before 9705 ± 130 yr B.P. The lower terrace is characterized by relatively thick, vertical-accretion deposits of silt loam that contain sequences of thin, buried A, color B, and C horizons. They were formed between about 3240 ± 110 (¹⁴C data of soil humin) and 235 ± 80 yr B.P. Deposits above the 235 ± 80 yr B.P. stratum are unweathered. The soil stratigraphy and ¹⁴C dates of soil humin from buried A horizons are surprisingly well correlated between sites. Most sediments of the present flood plain have been deposited since 1120 ± 80 yr B.P. Incipient A horizons and oxidation of inherited organic matter in the subsoil are the only evidence of pedogenesis in the flood-plain deposits that are older than 275 ± 80 yr B.P. The most recent flood-plain fill deposited since then is unaltered. These youngest sediments of the flood plain along with the youngest veneer of vertical-accretion deposits on the lowest terrace are associated with an increased rate of deposition largely attributable to clearing of the forests by settlers, beginning in the late 1700s. Comparison of the alluvial stratigraphy with the radiocarbon-dated pollen stratigraphy of southwestern New York (Miller 1973) reveals some apparent time correlations between alluvial events and vegetation changes. This gives reason to speculate that climatic change or forest catastrophes such as disease or drought are causes of some of the alluvial events.     

Nivation landforms in the western Great Basin and their paleoclimatic significance

More than 10,000 nivation landforms occur in the higher mountain ranges of the western Great Basin. They range from small, subtle hollows with head scarps a few meters high and a few tens of meters long to broad, clearly defined terraces as much as 220 m wide bounded by bold, steeply sloping head scarps as much as 30 m high and 1600 m long. Distribution of these nivation hollows is strongly influenced by elevation, slope orientation, local relief, and substrate lithology. About 95% occur between 2200 and 3000 m elevation, and nearly 80% are situated on north-northwest-to east-northeast-facing slopes. They occur mainly in areas of moderately sloping terrain and moderate local relief, and they are preferentially developed on relatively incompetent substrates including terrigenous sedimentary deposits, volcanic and metavolcanic rocks of intermediate composition, and deeply weathered granitoid rocks. Nearly all of these nivation hollows are relict. They are most abundant near areas of late Pleistocene glaciation but rarely occur within such areas. Most are veneered with colluvium and are well vegetated, and many hollows in the Mono Basin area are veneered with volcanic ash at least 700 yr old. Distribution of nivation hollows suggests that (1) the full-glacial nivation threshold altitude (NTA) rose from north to south at 190 m per degree of latitude, subparallel to, and approximately 740 m lower than, the full-glacial equilibrium-line altitude (ELA) and about 1370 m lower than the estimated modern ELA; (2) the difference between the full-glacial and modern ELAs indicates an approximate 7°C full-glacial mean-annual-temperature depression throughout the Great Basin; and (3) the full-glacial mean annual temperature at the NTA is estimated to have been approximately 0° to 1°C, assuming little change in accumulation-season precipitation.     

A freshwater population of the mummichog,Fundulus heteroclitus,from the Susquehanna River drainage in Pennsylvania

An established population of mummichog,Fundulus heteroclitus, in the Susquehanna drainage is reported from Pennsylvania for the first time. Three year classes of this brackish water species were taken on 17 August 1976 from Letort Spring Run, a tributary of the Conodoguinet Creek in Cumberland County. A survey of unpublished records and museum specimens revealed occurrences in Wissahickon Creek, Montgomery County, and Brandywine Creek, Chester County; both Delaware drainage. Presence in these drainages is believed the result of bait bucket introduction.     

Emplacement and Differentiation of the York Haven Diabase Sheet, Pennsylvania

Many of the high-Ti quartz-normative tholeiitic intrusive sheetsin the early Mesozoic rift basins of the Eastern USA exhibitlateral differentiation from mafic cumulate units, through diabase,to relatively evolved iron-rich rock types. We have investigateda representative example in detail, the York Haven sheet inthe Gettysburg basin of south–central Pennsylvania. Itranges in thickness from 330 m to 675 m, and we have sampledit from base to top along four separate stratigraphic sectionsevenly spaced over the extent of the intrusion. The easternmostsection (York Haven) is entirely basaltic bronzite cumulate(average 15 vol. % bronzite), whereas the westernmost (ReesersSummit) consists of diabase and low-MgO diabase with a middleto upper ‘sandwich zone’ of ferrogabbro. The interveningsections feature rock types transitional between the two end-membersequences. Chemically, the rock series shows a gradual eastto west depletion of compatible elements (Mg, Ca, Ni, and Cr),and enrichment of incompatible elements [Ti, Fe, Na, K, P, Cu,Zr, Th, Ta, Hf, Sb, Cs, As, platinum group elements (PGEs),and rare earth elements (REEs)]. We suggest two main processes for the trends observed in theYork Haven sheet. First, flow differentiation during ascentand lateral injection of the parental magma produced a tongueof basaltic bronzite cumulate that thins from southeast to northwestand passes laterally into diabase, and, at the distal end ofthe intrusion, into low-MgO diabase. Then, in the latter stagesof crystallization, densitydriven hydrothermal fluids transportedincompatible elements westward, into structurally higher partsof the intrusion. Reaction of this residual aqueous fluid withpartly crystallized low-MgO diabase produced a zone of ferrogabbrorich in hydrothermal replacement products (e.g., Cl-amphibole,biotite, ferrohypersthene, and skeletal ilmenite) and precipitates(e.g., quartz, fayalite, Cl-apatite, sulfides, and PGE minerals). ^* Present address: US Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park, Hawaii 96718     

Preliminary estimates of regolith generation and mobility in the Susquehanna Shale Hills Critical Zone Observatory,Pennsylvania, using meteoric 10Be

This study seeks to quantify the rate and timing of regolith generation in the Critical Zone at the Susquehanna Shale Hills Critical Zone Observatory (SSHO). Meteoric ¹⁰Be depth profiles were determined using measurements from 30 hillslope soil and bedrock core samples in an effort to constrain ¹⁰Be inventories. The SSHO is located in the temperate climate zone of central Pennsylvania and comprises a first-order watershed developed entirely on a Fe-rich, organic-poor, Silurian-aged shale. Two major perturbations to the landscape have occurred at SSHO in the geologically recent past, including significant and sustained periglacial activity until after the retreat of the Laurentide ice sheet (～21 ka) and deforestation during early colonial land-use. Bulk soil samples (n = 16) were collected at three locations along a planar hillslope on the southern ridge of the catchment, representing the ridge top, mid-slope and valley floor. Rock chip samples (n = 14) were also collected from a 24 m deep core drilled into the northern ridge top. All meteoric ¹⁰Be concentration profiles show a declining trend with depth, with most of the ¹⁰Be retained in the uppermost decimeters of the soil. Meteoric ¹⁰Be inventories are higher at the mid-slope and valley floor sample sites, at 3.71 ± 0.02 × 10¹⁰ at/cm² and 3.69 ± 0.02 × 10¹⁰ at/cm², than at the ridge top site (1.90 ± 0.01 × 10¹⁰ at/cm²). The ¹⁰Be inventory at the convex ridge top site implies a minimum residence time of ～10.6 ka, or if erosion is steady, an erosion rate of 19.4 ± 0.2 m/My.     

Incision of a river curvature due to exhumed Miocene volcanic landforms: Danube Bend, Hungary

A new model for the formation and relief evolution of the Danube Bend, northern Hungary, is discussed on geomorphological and volcanological grounds. We propose that the present-day U-shaped loop of the Danube Bend was partly inherited from the horseshoe caldera morphology of Keserűs Hill volcano, a mid-Miocene (ca 15 Ma) lava dome complex with an eroded central depression open to the north. According to combined palaeogeographical data and erosion rate calculations, the drainage pattern in the Danube Bend region was formed when Pleistocene tectonic movements resulted in river incision and sedimentary cover removal. Formation of the present curvature of the river was due to the exhumation of the horseshoe-shaped caldera as well as the surrounding resistant volcaniclastic successions (i.e. Visegrád Castle Hill) and a hilltop lava dome (Szent Mihály Hill). The process accelerated and the present narrow gorge of the Danube Bend was formed by very rapid, as young as late Quaternary differential tectonic uplift, also enhancing the original volcanic morphology. On the basis of comparative long-term erosion-rate calculations, we estimated successive elevation changes of the volcanic edifice, including partial burial in late Miocene time. In comparison with various order-of-magnitude changes, the mid-to-late Quaternary vertical movements show increased rates and/or base level drop in the Pannonian Basin.     

Ammonium regeneration and biomass of macrozooplankton and ctenophores in Great South Bay,New York

The rate of zooplankton ammonium regeneration was measured in Great South Bay, Long Island, New York, between July 1982 and May 1984. Ammonium excretion by macrozooplankton (>200 μm) ranged from 7 μg atoms NH₄ ¹⁺?N m^?3 d^?1 in winter to 156 μg-atoms NH₄ ¹⁺?N m^?3 d^?1 in spring. Ammonium excretion by ctenophores was greater than or equivalent to that of macrozooplankton during the period of ctenophore biomass maximum in summer and fall. The temperature coefficient (Q₁₀) for NH₄ ¹⁺ excretion was 1.74 from 2.2 to 27.5°C for macrozooplankton and 1.63 between 17 and 26°C for the ctenophores. Ammonium nitrogen excretion by macrozooplankton and ctenophores combined, accounted for 1 to 3% of phytoplankton nitrogen requirements in summer when primary productivity was high and 39% in the spring. *** DIRECT SUPPORT *** A01BY040 00005     

西藏门巴地区层状地貌特征及其形成机制

西藏门巴地区发育多级层状地貌,即不同高度的山顶面、盆地面与多级河谷阶地地貌。深入研究这些层状地貌的特征、成因和形成时代,是探讨青藏高原隆升年代、幅度和过程的重要途径。对该区层状地貌的研究表明:门巴地区不同高度的山顶面是渐新世晚期形成的老夷平面在高原持续隆升过程中解体后的残留;不同规模和方向的盆地地貌面是高原隆升过程中伸展作用的产物。研究区广泛分布的多级阶地表明0.15 Ma(共和运动)以来该区又进入了强烈的隆升时期。     

Diversity of murtoos and murtoo-related subglacial landforms in the Finnish area of the Fennoscandian Ice Sheet

Murtoos are recently discovered triangular-shaped subglacial landforms that form under warm-based ice and in association with significant subglacial meltwater flow. They appear in distinct fields and commonly occur in the area that was covered by the Fennoscandian Ice Sheet during glacial periods. Murtoos potentially represent a transition form from non-channelized to channelized subglacial drainage networks. In the present study, we analyse and classify murtoos and murtoo-related landforms in the Finnish area of the Fennoscandian Ice Sheet based on their characteristics and appearance in LiDAR-based digital elevations models. Combined with morphometric analyses, the observations suggest that five types of murtoos and murtoo-related landforms are common and widespread in Finland: (i) triangle-type murtoos (TTMs), (ii) chevron-type murtoos (CTMs), (iii) lobate-type murtoos (LTMs), (iv) murtoo-related ridges and escarpments (MREs), and (v) other murtoo-related polymorphous landforms (PMRs) that look like small mounds and ridges. The morphometric characteristics of the different types are described here in detail, and it is shown that they are spatially and geomorphologically related. In addition, we provide examples of murtoos other than the TTMs to demonstrate that different murtoo types and murtoo-related landforms are composed of similar sediments and architectural characteristics. The diversity of murtoo landforms and the transition between distinct murtoo types indicate rapid and complicated variations in the configuration of subglacial hydrology at different spatial and temporal scales. This study emphasizes the essential role of subglacial meltwater in the shaping of glacial landscapes and the redistribution of large volumes of sediments during the deglaciation of the Fennoscandian Ice Sheet.     

Ground-water geochemistry of uranium and other elements, Monticello area, New York

About 500 well and spring waters were collected on an approximately 1-km spacing in an area centered on six small U and Cu-U occurrences near Monticello, N.Y., as an orientation survey in the NURE program. Rocks of the area belong to the Devonian Catskill Group and are predominantly red sandstones and shales of fluvial origin. The sediments dip 0–5° in the main part of the area, but steepen to 45° in the east. The ground waters were analyzed for 46 elements plus several other water properties.An R-mode factor analysis extracted 10 factors. The strongest factor, termed “Dissolved solids”, has heavy loadings on most major elements, plus U, B, Li, Sr, and Zn. This factor is attributed to varying degrees of interaction between original rainwater and rocks. Recognition of anomalies for elements loaded on this factor is aided by evaluation of ratios or plots against total dissolved solids or conductivity. Three weaker factors apparently represent admixtures with two types of deep brine and with waters of enhanced Fe-Mn resulting from reducing conditions. Other factors include an assemblage of insoluble trace metals and a Zn-Cu-P factor, both possibly related to contamination and/or analytical problems, a rare earth group, and an Se-As-Ag factor. The waters are clearly complex mixtures of effects.The geographic distribution of high U values shows some correlation with the distribution of U occurrences, but many equally high values occur outside the known mineralized area. When the data are projected to a vertical section normal to the strike, high U values define two gently dipping aquifers. The upper anomalous aquifer contains the known occurrences but extends downdip. Samples within this aquifer show patterns in U, dissolved O₂, and conductivity, apparently related to influx of fresh water from updip, along major rivers, and along possible fractured zones. High He values are also most numerous near the occurrences and define the deeper U-rich aquifer. The interpretation of the data is greatly clarified by separation of individual aquifers.Saturation indices are generally −3.4 to −5 and show patterns similar to dissolved U, except for values of −6 to −9 in a few samples with high phosphate. Predominant U species are usually UO₂(CO₃)₂²⁻, or less commonly UO₂CO₃⁰ or UO₂(HPO₄)₂²⁻.     

A multivariate sedimentary environmental analysis of Great South Bay and South Oyster Bay, New York

A multivariate statistical strategy for classifying paleoenvironments is effective for studying modern sedimentary processes in western Great South Bay and South Oyster Bay, New York. The 13 whole phi weight percent variables were tested for redundancy with R-mode cluster analysis. The samples were partitioned statistically into five environmentally significant facies using Q-mode cluster analysis: (A)sandy gravel, (B)sandy silt, (C)silty sand, (D)slightly gravelly sand, and (E)fine sand. An ordination depicted gradational relationships among the samples and the facies. It was used to evaluate the environmental and textural parameter gradients within the sample space. Interpretations obtained in this manner and by examination of the grain-size curves suggest that these sediments were deposited by waves and currents on beaches and in wave zones (facies C and E),shoal areas (facies B),and tidal channels (facies A and D).Tidal currents, wave action, and eelgrass control the distribution of sediments within the two bays.     

川西高原巴塘地区可溶岩地层分布与岩溶地貌发育特征

以川西高原巴塘县、白玉县为研究对象,详细阐述研究区从三叠系到寒武系出露的主要可溶岩地层的分布、岩石成分、结构特征以及各地层的岩溶发育特征,系统总结出研究区可溶岩地层的特征和碳酸盐岩地层岩溶发育的规律。结果表明:研究区可溶地层呈北西南东向展布,明显受区域地质构造影响;岩溶地貌发育特征显示出与青藏高原主要地区岩溶地貌的一致性,属第三纪时期热带—亚热带环境下发育演化的覆盖型岩溶剥露地表而形成的古岩溶,且岩溶类型多样,形态与规模空间差异性明显;不同碳酸盐岩地层的岩溶发育程度统计显示,泥盆系溶蚀洼地所占面积最大,三叠系与志留系碳酸盐岩地层中溶蚀洼地个数较多,但发育密度低于泥盆系,二叠系溶蚀洼地个数与面积均为最小,石炭系地层由于碳酸盐岩纯度高且集中出露,溶蚀洼地发育密度最大。      

The nature of deformation within the outer limits of the central appalachian foreland fold and thrust belt in New York state

Residual strain, a self-equilibrating recoverable strain that remains in rocks even after external forces and moments are removed, is found NNW of the folded Appalachian plateau in the Devonian Onondaga limestone and the Silurian Lockport dolomite and Grimsby sandstone of western New York. This residual strain is manifest upon overcoring by a NNW directed maximum expansion of the limestone and sandstone and a random maximum expansion of the dolomite. Strains, recorded with strain gauge rosettes bonded to outcrops, are as high as 200 με (microstrain). Double overcoring of the sandstone and dolomite relieves smaller strains of the same orientation as the initial overcore. X-ray analysis of the Grimsby sandstone shows that the elastic residual strain locked in quartz grains is characterized by a NE principal extension of 60 με and a 10–30 με NW principal compression oriented 30° counterclockwise from the NNW compression indicated by overcoring. Sonic velocity tests on samples in the lab indicate that Grimsby sandstone is anisotropic with a NNW maximum P-wave velocity of 4.05 km/sec. This anisotropy correlates with the residual strain in Grimsby sandstone. Mechanical twinning of calcite within both the Onondaga limestone and Grimsby sandstone indicates that the rock contains a permanent compressive strain of less than 2% in the NNW direction. The permanent strain becomes progressively smaller in a series of samples from Syracuse to Buffalo, New York. The development of solution cleavage in Onondaga limestone also indicates a NNW compression. No evidence of permanent strain was found in the dolomite. The NNW compression of the limestone and sandstone is normal to the fold axes of the Appalachian foreland fold and thrust belt. This geometric relationship indicates that the residual strain well beyond the outermost Appalachian folds was caused by the same tectonic stresses responsible for folding, the Appalachians during the late Paleozoic. Strain within the Appalachian plateau below the Silurian salt horizon suggests either the presence of a second décollement in, perhaps, Ordovician shales or a general NNW shortening of the crust under the Appalachian plateau.     

Using landforms of Saudi Arabia for scenic and recreational purposes (With special reference to the Riyadh area)

The landform of Saudi Arabia in general and the Riyadh area in particular have their own potentiality for scenic and recreational purposes. The higher lands or features which have well cemented material in some areas of Riyadh have been recommended for scenic use, while lower lands like wide natural lakes, sand dunes and others can be mostly used for recreational purposes. Such features and purposes found here may be extrapolated into other similar areas within Saudi Arabia and may be compared with other areas elsewhere in the world.     

大兴安岭地区新仙女木事件的表现特征

新仙女木事件是末次冰消期期间发生的一次气候转冷事件,该事件对整个北半球的中高纬度地区的气候变化有明显的影响。然而,在该事件造成东亚中高纬地区温度下降的统一认识下,对于其季节性特征仍较为缺乏认识。本文用大兴安岭中部月亮湖末次冰消期多指标记录,揭示了大兴安岭地区在新仙女木事件期间植被中的北方针叶林成分增加、森林发育、冬季温度下降、东亚冬季风明显增强。

     

Seasonal-Scale and Decadal-Scale Sediment-Vegetation Interactions on the Subaqueous Susquehanna River Delta,Upper Chesapeake Bay

Submersed aquatic vegetation (SAV) have been a prominent feature on the Susquehanna Flats, the shallow, subaqueous delta of the Susquehanna River, Maryland. SAV were absent from the Flats between 1972 and 2000, but have since recovered. While it is well established that SAV can improve water quality by promoting sediment and nutrient retention, it is not well understood how SAV on the Flats modulate sediment input from the Susquehanna River into the Upper Chesapeake Bay over different timescales. This study evaluates sedimentation on the Flats over seasonal to decadal timescales, using naturally occurring radioisotopes (⁷Be, ²¹⁰Pb) within the context of SAV biomass and Flats geomorphology. Results indicate that sedimentation on the Flats is both spatially and temporally variable. Although this variability cannot be explained by relationships with grain size and SAV biomass, river discharge, sediment supply, and geometry over the SAV bed likely control sedimentation in this system. Decadal-scale sedimentation is influenced by both flood events and changes in SAV biomass abundance. Average annual sediment accumulation was higher when SAV were present than when SAV were absent. SAV bed area was strongly correlated with average annual accumulation rate. These results suggest that a positive feedback between SAV abundance and accumulation rate exists; however, sediment supply and transport pathways are also important factors.     

Speciation of aluminum in the stream waters from the Susquehanna River watershed, Chesapeake Bay

 The aim of this paper was to analyze the processing and transport of aluminum speciation through the terrestrial and aquatic ecosystems of the Chesapeake Bay landscape. Stream waters were sampled in 14 different streams from the Susquehanna River watershed to the upper reach of Chesapeake Bay. The basic water quality data were documented and Al speciation was evaluated by modified MINEQL computer model. It was found that the increase in acidity in some of the stream waters near New York were closely linked with a marked decline in basic cation concentrations. In these areas, the sum of the toxic forms of Al³⁺ plus AlOH²⁺ and Al(OH)₂ ⁺ concentrations exceeds the critical level of 5 μmol l^–1. A potential threat from aluminum may occur. Received: 3 January 2000 · Accepted: 21 March 2000     

Aquifer geochemistry at potential aquifer storage and recovery sites in coastal plain aquifers in the New York city area,USA

The effects of injecting oxic water from the New York city (NYC) drinking-water supply and distribution system into a nearby anoxic coastal plain aquifer for later recovery during periods of water shortage (aquifer storage and recovery, or ASR) were simulated by a 3-dimensional, reactive-solute transport model. The Cretaceous aquifer system in the NYC area of New York and New Jersey, USA contains pyrite, goethite, locally occurring siderite, lignite, and locally varying amounts of dissolved Fe and salinity. Sediment from cores drilled on Staten Island and western Long Island had high extractable concentrations of Fe, Mn, and acid volatile sulfides (AVS) plus chromium-reducible sulfides (CRS) and low concentrations of As, Pb, Cd, Cr, Cu and U. Similarly, water samples from the Lloyd aquifer (Cretaceous) in western Long Island generally contained high concentrations of Fe and Mn and low concentrations of other trace elements such as As, Pb, Cd, Cr, Cu and U, all of which were below US Environmental Protection Agency (USEPA) and NY maximum contaminant levels (MCLs). In such aquifer settings, ASR operations can be complicated by the oxidative dissolution of pyrite, low pH, and high concentrations of dissolved Fe in extracted water.