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Alan B. Binder Manfred A. Lange Heinz-Jürgen Brandt Susanne Kähler 《Earth, Moon, and Planets》1980,23(4):445-481
A synthesis of the majority of the available mare basalt data shows that basalts and glasses came from 28 different volcanic units. The compositions of the magmas of 12 of these units can be calculated with a high degree of confidence. Reasonable estimates can be made for the compositions of nine of the remaining units. In addition, the compositions of three general magma types can be obtained from data derived from the Luna 16, Luna 24, and Apollo 17 fines. The compositional data presented provide a firm basis for the further study of the characteristics of the mare basalt magma source region. 相似文献
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Mi-Kyung Yoon Mikhail Baykulov Stefan Dümmong Heinz-Jürgen Brink Dirk Gajewski 《International Journal of Earth Sciences》2008,97(5):887-898
The influence of deep crustal processes on basin formation and evolution and its relation to current morphology is not well
understood yet. A key feature to unravel these issues is a detailed seismic image of the crust. A part of the data recorded
by the hydrocarbon industry in the late 1970s and 1980s in the North German Basin were released to the public recently. The
seismic reflection data were recorded down to 15 s two-way travel time. The mean Common Midpoint fold of about 20 is relatively
low compared to contemporary seismic acquisitions. The processing of the 1980s focussed on the sedimentary structures to explore
the hydrocarbon potential of this area. We applied the Common Reflection Surface stack technique to the data sets, which is
well suited for low-fold data. The reprocessing was focussed on the imaging of the subsedimentary crustal range. The reprocessed
images show enhanced reflections, especially in the mid and lower crustal part. Also, the image of the salt structures in
the graben area was improved. Furthermore, the reprocessed images indicate an almost flat Moho topography in the area of the
Glückstadt Graben and an additional lower crustal structure, which can be correlated with a high-density body found in recent
gravity modeling studies. 相似文献
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Werner?SchreyerEmail author Heinz-Jürgen?Bernhardt André-Mathieu?Fransolet Thomas?Armbruster 《Contributions to Mineralogy and Petrology》2004,147(3):276-287
Kanonaite, with compositions plotting on the join Mn3+AlSiO5–Fe3+AlSiO5, was discovered in a late quartz vein of the Le Coreux metamorphic manganese deposit. A typical structural formula is (Mn3+3.69Fe3+0.36)Al3.95Si4.00O20, representing maximum solid solution within the system Al2SiO5–Mn2SiO5–Fe2SiO5. Refractive indices are =1.777; =1.855. The end-member compositions form the outermost, latest products in zoned crystals ranging to less manganiferous kanonaite. A crystal structure determination of a Mn-rich kanonaite confirms that about 96% of all the Mn3+ present is located in the strongly Jahn-Teller-distorted octahedron of the andalusite-type structure. Combining all relevant mineral-chemical and petrological data available on the deposit, a speculative model is presented in which kanonaite crystals with successively higher Mn3+ contents form during decreasing temperatures in the course of the anticlockwise PTt path of extensional metamorphism. Kaolinite occurring in zones within composite kanonaite porphyroblasts of adjacent phyllites is regarded here as by-product of a continuous retrograde breakdown reaction of less manganiferous kanonaite. In places, kanonaite was peripherally replaced by muscovite and Mn- and Fe-oxides.Editorial responsibility: J. HoefsDedicated to the late Dr. H.S. Yoder, Jr. 相似文献
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Werner Schreyer André-Mathieu Fransolet Heinz-Jürgen Bernhardt 《Contributions to Mineralogy and Petrology》2001,141(5):560-571
In a newly found type of quartz vein cross-cutting the famous "viridine"-bearing phyllites at Le Coreux, hollandite, ideally BaMn8O16, was discovered for the first time at this locality and in Belgium. Because the crystals contain up to 60 mol% of the Sr end member, this is also the second occurrence of strontiomelane. The coexisting "viridine" (= kanonaite) contains the highest amount (88 mol%) of the ideal end member MnAlSiO5 ever found worldwide. The hollandite-type minerals are intimately intergrown with braunite containing appreciable Ca and Mg. Ba-bearing muscovite, Fe-poor excess-Al clinochlore (not quite trioctahedral), and albite are the remaining accessory minerals in the dominant quartz matrix. Microprobe analyses of all phases show rather extreme element fractionations: nearly all K is located in muscovite and none in the hollandite phase despite the existence of the end member KMn8O16 (cryptomelane). Similarly, nearly all Na is in albite and not in hollandite (no NaMn8O16=manjiroite component). Nearly all Mn resides in the two oxide phases and in kanonaite. Mg is strongly fractionated into chlorite. The small amounts of Fe and Ti present are predominantly partitioned into the hollandite phase, which also accommodates most of the Ba and Sr. Indeed, the hollandite phase is stabilized by the latter two elements relative to other Mn oxides. Kanonaite is stabilized by Al. Although no requisite sites are available in its crystal structure, braunite always contains small amounts of Ba and Sr. However, the Sr/(Sr+Ba) ratios in braunite are spurious and unrelated to those of the directly adjoining hollandite phases The conditions of formation of these veins may be well below 300 °C at low pressures (1-2 kbar), in agreement with the experimental results that the maximum Mn contents in kanonaite increase with falling temperatures. 相似文献
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Thomas Reinecke Heinz-Jürgen Bernhardt Richard Wirth 《Contributions to Mineralogy and Petrology》2000,139(5):584-606
Calcite in former aragonite–dolomite-bearing calc-schists from the ultrahigh-pressure metamorphic (UHPM) oceanic complex
at Lago di Cignana, Valtournanche, Italy, preserved different kinds of zoning patterns at calcite grain and phase boundaries.
These patterns are interpreted in terms of lattice diffusion and interfacial mass transport linked with a heterogeneous distribution
of fluid and its response to a changing state of stress. The succession of events that occurred during exhumation is as follows:
As the rocks entered the calcite stability field at T=530–550 °C, P ca. 1.2 GPa, aragonite occurring in the matrix and as inclusions in poikilitic garnet was completely transformed to calcite.
Combined evidence from microstructures and digital element distribution maps (Mn-, Mg-, Fe- and Ca–Kα radiation intensity
patterns) indicates that transformation rates have been much higher than rates of compositional equilibration of calcite (involving
resorption of dolomite and grain boundary transport of Mg, Fe and Ca). This rendered the phase transformation an isochemical
process. During subsequent cooling to T ca. 490 °C (where lattice diffusion effectively closed), grains of matrix calcite have developed diffusion-zoned rims, a
few hundred micrometres thick, with Mg and Fe increasing and Ca decreasing towards the phase boundary. Composition profiles
across concentrically zoned, large grains in geometrically simple surroundings can be successfully modelled with an error
function describing diffusion into a semi-infinite medium from a source of constant composition. The diffusion rims in matrix
calcite are continuous with quartz, phengite, paragonite and dolomite in the matrix. This points to an effective mass transport
on phase boundaries over a distance of several hundred micrometres, if matrix dolomite has supplied the Mg and Fe needed for
incorporation in calcite. In contrast, diffusion rims are lacking at calcite–calcite and most calcite–garnet boundaries, implying
that only very minor mass transport has occurred on these interfaces over the same T–t interval. From available grain boundary diffusion data and experimentally determined fluid–solid grain boundary structures,
inferred large differences in transport rates can be best explained by the discontinuous distribution of aqueous fluid along
grain/phase boundaries. Observed patterns of diffusion zoning indicate that fluid was distributed not only along grain-edge
channels, but spread out along most calcite–white mica and calcite–quartz two-grain junctions. On the other hand, the inferred
non-wetting of calcite grain boundaries in carbonate-rich domains is compatible with fluid–calcite–calcite dihedral angles
>60° determined by Holness and Graham (1995) for a wide range of fluid compositions under the P–T conditions of interest. Whereas differential stress has been very low at the stage of diffusion zoning (T > 490 °C), it increased as the rocks were cooling below 440 °C (at 0.3–0.5 GPa). Dislocation creep and the concomitant increase
of strain energy in matrix calcite induced migration recrystallisation of high-angle grain boundaries. For that stage, the
compositional microstructure of recrystallised calcite grain boundary domains indicates significant mass transport along calcite
two-grain junctions, which at the established low temperatures is likely to have been accomplished by ionic diffusion within
a hydrous grain boundary fluid film (“dynamic wetting” of migrating grain boundaries).
Received: 10 January 2000 / Accepted: 10 April 2000 相似文献
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