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An approach for instantaneous ambiguity resolution for medium- to long-range multiple reference station networks 总被引：2，自引：2，他引：2
G. Hu D. A. Abbey N. Castleden W. E. Featherstone C. Earls O. Ovstedal D. Weihing 《GPS Solutions》2005,9(1):1-11
Integer ambiguity resolution (AR) is a prerequisite for all high-precision (centimetre level) GPS applications that utilise multiple reference station (MRS) networks. However, due to the presence of distance-dependent GPS errors, notably atmospheric refraction, AR across the network is difficult on an epoch-by-epoch basis, especially for medium- to long-range (typically 30–130 km as used here) MRS networks. This paper presents an approach for medium- to long-range instantaneous AR for MRS networks, based on an ionosphere-weighted observation model and network geometry constraints, along with a multiple ambiguity validation test procedure. The performance of the proposed method was demonstrated through two case-study examples from Australia and Norway. Our test results show that the instantaneous AR success rate varied from 93% (131 km baseline) to 98% (35 km baseline). It is also shown that the adopted high-precision prediction models for the double-difference (DD) ionospheric delay and residual tropospheric zenith delay (RTZD) are of benefit to the high success rate of the network AR. Due to its epoch-by-epoch nature, the proposed approach is insensitive to cycle-slips, rising or setting satellites, or loss-of-lock. 相似文献
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Ocean Dynamics - In this study, we diagnose the time variability and vertical structure of the high- and low-frequency motions on the Mississippi-Alabama Shelf as observed with a bottom-mounted... 相似文献
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许多研究资料都报道过造山晚期的横推断裂系统中以H2o－Co2－NaCl为主的流体与脉岩型金矿化的关系。其中一些系统中存在晚期的低温、高盐度卤水。这种卤水被认为是晚期分离作用的产物或作为叠加的流体导致同位素年龄再造并产生新的矿物组合。然而,目前还难以建立卤水与金矿化之间的成因联系．为此我们对北爱尔兰Curraghinalt石英－硫化物－金矿脉型矿床的结构、流体包裹体和同位素资料进行研究,这些资料不仅显示了是地表水渗入到原有的金矿中,而且也为低温、高盐度的CaCl2－NaCl流体促使金再活化提供了新证据。虽然还缺乏对金搬运机理的明确解释,但对认识与卤水有关的金矿化的形成有重要意义。 1 地质特征 位于北爱尔兰Curraghinalt 的石英脉型金矿床是英国最大金产地,是沿着主断裂系--高原边界断裂带(HBFZ)--分布的一系列矿床之一。 相似文献
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Steven P. Hollis Stephen Roberts Garth Earls Richard Herrington Mark R. Cooper Stephen J. Piercey Sandy M. Archibald Martin Moloney 《Mineralium Deposita》2014,49(5):575-593
Although volcanogenic massive sulfide (VMS) deposits can form within a wide variety of rift-related tectonic environments, most are preserved within suprasubduction affinity crust related to ocean closure. In stark contrast to the VMS-rich Appalachian sector of the Grampian-Taconic orogeny, VMS mineralization is rare in the peri-Laurentian British and Irish Caledonides. Economic peri-Gondwanan affinity deposits are limited to Avoca and Parys Mountain. The Tyrone Igneous Complex of Northern Ireland represents a ca. 484–464 Ma peri-Laurentian affinity arc–ophiolite complex and a possible broad correlative of the Buchans-Robert’s Arm belt of Newfoundland, host to some of the most metal-rich VMS deposits globally. Stratigraphic horizons prospective for VMS mineralization in the Tyrone Igneous Complex are associated with rift-related magmatism, hydrothermal alteration, synvolcanic faults, and high-level subvolcanic intrusions (gabbro, diorite, and/or tonalite). Locally intense hydrothermal alteration is characterized by Na-depletion, elevated SiO2, MgO, Ba/Sr, Bi, Sb, chlorite–carbonate–pyrite alteration index (CCPI) and Hashimoto alteration index (AI) values. Rift-related mafic lavas typically occur in the hanging wall sequences to base and precious metal mineralization, closely associated with ironstones and/or argillaceous sedimentary rocks representing low temperature hydrothermal venting and volcanic quiescence. In the ca. 475 Ma pre-collisional, calc-alkaline lower Tyrone Volcanic Group rift-related magmatism is characterized by abundant non-arc type Fe-Ti-rich eMORB, island-arc tholeiite, and low-Zr tholeiitic rhyolite breccias. These petrochemical characteristics are typical of units associated with VMS mineralization in bimodal mafic, primitive post-Archean arc terranes. Following arc-accretion at ca. 470 Ma, late rifting in the ensialic upper Tyrone Volcanic Group is dominated by OIB-like, subalkaline to alkali basalt and A-type, high-Zr rhyolites. These units are petrochemically favorable for Kuroko-type VMS mineralization in bimodal-felsic evolved arc terranes. The scarcity of discovered peri-Laurentian VMS mineralization in the British and Irish Caledonides is due to a combination of minimal exploration, poor-preservation of upper ophiolite sequences, and limited rifting in the Lough Nafooey arc of western Ireland. The geological and geochemical characteristics of the Tyrone Volcanic Group of Northern Ireland and peri-Gondwanan affinity arc/backarc sequences of Ireland and northwest Wales represent the most prospective sequences in the British and Irish Caledonides for VMS mineralization. 相似文献
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