Geoarchaeology at Gilman Falls: An Archaic quarry and manufacturing site in central Maine,U.S.A.

Interdisciplinary investigations at the Milford Reservoir, central Maine, resulted in excavation and analysis of a Middle Archaic quarry and manufacturing site at Gilman Falls, dated to between 7300 and 6300 yr B.P. Lithological analysis indicates that the majority of the artifacts came from very local outcrops, providing low‐grade metamorphic rocks. Native Americans used a specialized technique to reduce the granofels and other rocks to long rods, artifacts commonly placed in local cemeteries. The Gilman Falls site was largely abandoned once these artifacts were no longer in vogue. Therefore, access to particular bedrock outcrops seems to have played an important role in site selection. Gilman Falls and other early to middle Holocene sites are preserved where bedrock sill dams ponded water that deposited fine sand. Early site sedimentation history is paralleled by a drainage change in the headwaters of the Penobscot River. Evidence for lower mid‐Holocene lake levels and a period of higher temperatures and lower precipitation may correlate with the sedimentation history. © 2001 John Wiley & Sons, Inc.     

Quantifying and simulating stormwater runoff in watersheds

We developed the Stormwater Runoff Modeling System (SWARM) based on curve number and unit hydrograph methods of the U.S. Department of Agriculture, Natural Resources Conservation Service. SWARM models single events, targets watersheds fitting easily within hydrologic units with 12‐digit codes, and has been calibrated for low‐gradient topography of the Southeast coastal plain. We established protocols; made changes related to peak rate factors, travel time formulas, curve numbers, and the initial abstraction ratio; and then tested the output with multi‐site validation using U.S. Geological Survey measurements of discharge and rainfall. Validation results from both undeveloped and developed watersheds support the robustness of our system in quantifying and simulating runoff: rainfall to runoff differences between measured and simulated volumes ranged from 3 to 11%; r² for hydrograph curves ranged from 0.82 to 0.98. SWARM can be a useful tool for scientific research and for coastal resource management and decision making in the Southeast coastal plain specifically and also may be applied to other areas by recalibrating parameters and modifying calculation templates. Copyright © 2012 John Wiley & Sons, Ltd.     

新疆哈密香山西铜镍-钛铁矿床系同源岩浆分异演化产物——矿相学、锆石U-Pb年代学及岩石地球化学证据

香山西岩体是东天山地区发现的唯一的一个铜镍-钛铁复合型含矿岩体,前人对香山西铜镍-钛铁矿床成因认识一直存在争议。本次通过矿相学研究结合电子探针分析,在香山西铜镍矿石中发现了铜镍硫化物与钛铁氧化物共生的现象,并首次测定了香山西钛铁辉长岩的SIMS锆石U-Pb年龄为278.6±1.8Ma(MSWD=1.2),与前人测得香山中岩体角闪辉长岩的锆石U-Pb年龄基本一致,证实了香山西铜镍矿与钛铁矿为共生关系,两者空间上渐变过渡。岩石地球化学研究表明,香山岩体(包括钛铁辉长岩)为同源岩浆经结晶分异作用形成的一套镁铁-超镁铁质岩体,具有拉斑玄武质岩浆分异演化趋势,并且经历了与地壳物质的混染。与中段和东段岩石相比,香山西辉长岩类具有相对高的REE、SiO₂(平均48.99%)、K₂O+Na₂O(平均3.43%)、TiO₂(平均1.26%)和明显低的Mg^#值(平均62.4),表现出分异演化程度高于中段和东段。经反演得出香山岩体原始岩浆含MgO约10%,FeO约9%,TiO₂约1.14%,与同一成矿带内其它含铜镍矿岩体原始岩浆成份相近,应为 普通的拉斑玄武质岩浆。因此,香山西钛铁矿床的形成机制可能是由普通的拉斑玄武质岩浆,经历了较高程度的分异演化导致钛铁氧化物在残余岩浆中逐步富集,岩浆在上升侵位过程中与地壳物质的混染,不仅促使了岩浆中硫化物的饱和,同时提高了岩浆体系的氧逸度,进而促使了钛铁氧化物结晶沉淀。对香山西钛铁矿床成因研究的启示意义在于,除我国攀西地区高钛的玄武质岩浆外,普通的拉斑玄武质岩浆,在有利的分异演化条件下(如初始低氧逸度、相对高度的分异演化、后期与地壳物质混染)也有可能形成大型钛铁矿床。     

Geoarchaeology of Johns Bay,Maine

This study examines the Holocene history of a glacially-sculpted Maine embayment using both geological and archaeological data bases. High-resolution seismic profiling, in combination with vibracores and Holocene sea-level curves, were used to develop the Holocene stratigraphy and paleogeographic evolution of Johns Bay and Pemaquid Beach, Maine. These geological databases were, whenever possible, integrated with the Johns Bay archaeological database and general archaeological settlement paradigms for coastal Maine. As sea level has risen from its -65 m lowstand at the beginning of the Holocene, Johns Bay has evolved from a narrow fluvial system, to an estuary, to its present form of an open embayment. Over roughly the last 4000 years, the Pemaquid Beach area has changed from a forested upland, to a bedrock-pinned freshwater wetland, to a pocket barrier fronting a small salt marsh. The barrier continues to migrate over the salt marsh, which is transgressing the freshwater environments. The first evidence of human settlement in Johns Bay is at 4000–5000 yr B.P. Archaeological site distribution around Johns Bay has been examined in light of an estuarine embayment evolution model developed for the Maine coast. Sites are concentrated in zone 1 (the inner embayment). This zone is currently experiencing sediment accumulation. Zone 2 (middle embayment) is undergoing erosion, and zone 3 (outer embayment) has been stripped of sediment. Archaeological sites in these outer areas have been eroded. The Pemaquid Beach area has a history of occupation dating back 4000–5000 years. The last 2000 years of this record is found in stratigraphic context in the Nahanada site. The first 3000 years is represented by a collection of artifacts found out of context on the beach in front of the Nahanada site. The artifacts, dated by morphology, present a time continuum from 4000–5000 yr B.P. until the occupation of the Nahanada site. Thus, it is suggested that the Nahanada site represents the back of a chronologically shingeled settlement area that extended to the 5000 yr B.P. shoreline. Finally, a model for the development of chronologically shingled sites is suggested.     

Dietary transfer of fluoranthene from an estuarine oligochaete (Monopylephorus rubroniveus) to grass shrimp (Palaemonetes pugio): Influence of piperonyl butoxide

The objective of this study was to determine the potential for dietary transfer of sediment-associated fluoranthene from tubificid oligochaetes (Monopylephorus rubroniveus) to grass shrimp (Palaemonetes pugio). Grass shrimp, either in the presence or absence of sublethal waterborne concentrations of the metabolic inhibitor, piperonyl butoxide (PBO), were fed fluoranthene-dosed oligochaetes for 5-days. All grass shrimp bioaccumulated fluoranthene; however, bioaccumulation was 3X higher in the presence of PBO. Trophic transfer coefficients (TTCs) were 0.02 and 0.01 in the presence and absence of PBO, respectively. Following the 5-day accumulation period, shrimp in both treatments were allowed to depurate for 3 days. Depuration rates were significantly higher in PBO-exposed shrimp. These results demonstrated that sediment-associated fluoranthene can be transferred through the diet from oligochaetes to grass shrimp, and the presence of PBO enhanced fluoranthene bioaccumulation. However, the comparatively low TTCs suggest that biomagnification of fluoranthene in estuarine food webs is low.     

Hydrographic characterization of two tidal creeks with implications for watershed land use,flushing times,and benthic production

Many coastal ecosystems are undergoing anthropogenic stress from large increases in population and urbanization. In many regions changes in freshwater and material inputs to the coastal zone are altering the biogeochemical and biological capacities of ecosystems. Despite increased watershed inputs, large tidal volumes and flushing indicative of macrotidal estuaries can modulate the fate of introduced materials masking some of the symptoms of eutrophication. The Land Use Coastal Ecosystem Study (LU-CES) examined linkages between land use and environmental properties of Malind and Okatee Creeks in South Carolina from 2001 to 2004. The objectives of this particular study were to assess the hydrography of the two macrotidal creek ecosystems, explore differences in dissolved oxygen (DO), and develop a better understanding of the variations in primary and benthic secondary production in southeastern creek ecosystems. Depth, pH, salinity, and DO were reduced and more variable in Malind Creek than in Okatee Creek, although both creeks had strong semidiurnal frequencies in salinity time signatures. While time series analyses of DO saturation in Malind Creek revealed a dominant semidiurnal pattern, Okatee Creek had a distinctly diel DO pattern. The strongly semidiurnal fluctuations in DO and reduced flushing time indicated that biological processes were not fast enough to influence DO in Malind Creek. The Okatee Creek system had a much greater storage volume, a wider marsh, and a dominant 25-h DO frequency. These attributes contributed to an estimated 8–10 times more phytoplankton-based carbon in Okatee Creek and twice the annual benthic production. As expected from their proximity to the upland, low surface area, and high organic content, both ecosystems were net heterotrophic. This fundamental understanding of tidal creek hydrography is being used to help define linkages among differential watershed land uses, flushing characteristics, and levels of biological production in coastal ecosystems of the southeastern United States.