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991.
本文主要研究了GPS变形监测中垂直位移的问题。通过对误差分析,建立GPS大地高高差平差模型,以便提高GPS变形监测在垂直位移方向上的精度。从而真正的达到GPS三维监测。 相似文献
992.
993.
J. McPhie K. J. Ehrig M. B. Kamenetsky J. L. Crowley V. S. Kamenetsky 《Australian Journal of Earth Sciences》2020,67(5):699-716
AbstractAcropolis is an Fe-oxide–copper–gold prospect ~20?km from Olympic Dam, South Australia, and marked by near-coincident gravity and magnetic anomalies. Prospective Fe-oxide–apatite?±?sulfide veins occur in Mesoproterozoic and Paleoproterozoic volcanic and granitoid host units beneath unmineralised sedimentary formations. We have produced a geological map and history of the prospect using data from 16 diamond drill holes, including LA-ICPMS and high-precision CA-TIMS ages. The oldest unit is megacrystic granite of the Donington Suite (ca 1850?Ma). A non-conformity spanning ca 250 My separates the Donington Suite and felsic lavas and ignimbrites of the Gawler Range Volcanics (GRV; 1594.03?±?0.68?Ma). The GRV were intruded by granite of the Hiltaba Suite (1594.88?±?0.50?Ma) and felsic dykes (1593.88?±?0.56?Ma; same age as the Roxby Downs Granite at Olympic Dam). The felsic dykes are weakly altered and lack Fe-oxide–apatite–sulfide veins, suggesting that they post-date the main hydrothermal event. If correct, this relationship implies that the main hydrothermal event at Acropolis was ca 1594?Ma and pre-dated the main hydrothermal event at Olympic Dam. The GRV at Acropolis are the same age as the GRV at Olympic Dam and ca 3–7 My older than the GRV exposed in the Gawler Ranges. The gravity and magnetic anomalies coincide with sections through the GRV, Hiltaba Suite and Donington Suite that contain abundant, wide, Fe-oxide veins. The GRV, Hiltaba Suite and Donington Suite are unconformably overlain by the Mesoproterozoic Pandurra Formation or Neoproterozoic Stuart Shelf sedimentary formations. The Pandurra Formation shows marked lateral variations in thickness related to paleotopography on the underlying units and post-Pandurra Formation pre-Neoproterozoic faults. The Stuart Shelf sedimentary formations have uniform thicknesses.
- KEY POINTS
Fe-oxide–apatite?±?sulfide veins are hosted by the Gawler Range Volcanics (1594.03?±?0.68?Ma), the Hiltaba Suite granite (1594.88?±?0.50?Ma) and Donington Suite granite (ca 1850?Ma).
The age of felsic dykes (1593.88?±?0.56?Ma) interpreted to be post-mineralisation implies that the main hydrothermal event at Acropolis was ca 1594?Ma.
The Gawler Range Volcanics at Acropolis are the same age as the Gawler Range Volcanics at Olympic Dam and ca 3 to 7 My older than the Gawler Range Volcanics exposed in the Gawler Ranges.
994.
INTRODUCTION~hon0ffornjcelmtSwnthebasisofthestudyonthecrustaldefonnationanddeVel0prnent,thedistributionofndnereIs,andthendnerogeneticlawr.ThegeornagneticfieklisthecomP0siterefledionoftheformati0nanddefortnationofthecrust.Sornagnct-icsLLrVeydatacomPriseirnPortantbasisfordelincatingthearchiteCtonicelements,dCtendningtheirboundarylines,andanalopngthesanndarystrudriineachelernent,whicharetthernaintasks0fgoophySicalworkers.Thegoornagneticdelineati0nofanareahadforlongbodonequalitativeybyobs… 相似文献
995.
张赤军 《大地测量与地球动力学》1998,(2)
根据推导的公式计算了由山体质量引起的梯度效应,结果与实测值甚为接近。分析了佘山重力垂直梯度偏小的原因,认为这是由于山体质量分布引起的。最后讨论了垂直梯度偏小对重力值的高度归算和大地水准面的影响。 相似文献
996.
对蔡司公司的DiNi10数字电子水准仪,通过主要指标测试、条件试验和66km的实际外业测量,特别是与精密自平水准仪Ni002的40km同桩平行测量试验,论述了此种仪器的性能及其作业规律和特点。结果表明该仪器可用于一等水准测量和精密地形变监测。指出了该仪器的不足之处。 相似文献
997.
998.
镁资源研究与开发述评之一──镁水泥的研究与盐湖的开发 总被引:1,自引:0,他引:1
简单概括了镁资源研究开发的状况,评述镁水泥研究的主要理论成果。指出以镁水泥为途径开发盐湖资源的重要性。同时表述了镁水泥研究领域的最新动态,指出当前镁水泥研究需要考虑的几个重大问题。 相似文献
999.
Potential salinity limitations on nitrogen fixation in sediments from Mono Lake, California 总被引:2,自引:0,他引:2
David B. Herbst 《International Journal of Salt Lake Research》1998,7(3):261-274
Mono Lake is a hypersaline alkaline lake in the high altitude Great Basin desert of eastern California. Algal productivity
of the lake is nitrogen-limited, and a contributing source is derived from benthic nitrogen fixation. Lake level and salinity
have fluctuated with natural climatic variations but have also been affected by the diversion of tributary streams. This research
examines the influence of varied salinity and lake level on the potential for benthic nitrogen fixation in Mono Lake. A sediment-surface
microbial mat community was exposed directly, and in acclimated cultures, to a range of Mono Lake salinities under anaerobic
incubations and the activity of nitrogenase assayed by acetylene reduction. Activity was stimulated in light, but also occurred
in darkness. Over an experimental salinity range from 50 to 150 g L−1 TDS, nitrogenase activity was reduced by 90 per cent, with the activity persisting at the highest salinity being attributable
to dark fixation alone. Between a salinity of 50 g L−1, occurring in Mono Lake over 50 years ago, and 100 g L−1, nitrogenase activity was reduced by nearly half. Changes in the area of the littoral zone at varied lake levels also affect
the total amount of potential benthic nitrogen fixation in the lake. An accounting of yearly inputs of nitrogen to Mono Lake
suggests N2-fixation could contribute as much as 76–81 percent of the total. Inhibition of nitrogen fixation rates by increased salinity
could limit the long-term nutrient supply and benthic primary productivity of this ecosystem. 相似文献
1000.
以反解 Stokes公式为数学模型 ,应用由 T/ P测高数据计算的大地水准面高反演了海域平均重力异常 ,并与船测平均重力异常和 OSU91A位模型计算的平均重力异常进行了比对分析 ,得出了一些有益的结论。 相似文献