Comments on "Chaos in Daisyworld" by X. Zeng et al.     

STEPHEN D. JASCOURT  WILLIAM H. RAYMOND 《Tellus. Series B, Chemical and physical meteorology》1992,44(3):243-246

  相似文献   

Is Archaeopteryx the only old,cracked fossil?     

STEPHEN MORETON 《Geology Today》1988,4(3):83-84

  相似文献   

REE and PGE Geochemical Constraints on the Formation of Dunites in the Luobusa Ophiolite, Southern Tibet   总被引：19，自引：0，他引：19  

ZHOU  MEI-FU; ROBINSON  PAUL T.; MALPAS  JOHN; EDWARDS  STEPHEN J.; QI  LIANG 《Journal of Petrology》2005,46(3):615-639

The Luobusa ophiolite, Southern Tibet, lies in the Indus–YarlungZangbo suture zone that separates Eurasia to the north fromthe Indian continent to the south. The ophiolite contains awell-preserved mantle sequence consisting of harzburgite, clinopyroxene(cpx)-bearing harzburgite and dunite. The harzburgite containsabundant pods of chromitite, most of which have dunite envelopes,and the cpx-bearing harzburgites host numerous dunite dykes.Dunite also exists as a massive unit similar to those of themantle–crust transition zones in other ophiolites. Allof the dunites in the ophiolite have a similar mineralogy, comprisingmainly olivine with minor orthopyroxene and chromite and tracesof clinopyroxene. They also display similar chemical compositions,including U-shaped chondrite-normalized REE patterns. Mantle-normalizedPGE patterns show variable negative Pt anomalies. Detailed analysisof a chromite-bearing dunite dyke, which grades into the hostcpx-bearing harzburgite, indicates that LREE and Ir decrease,whereas HREE, Pd and Pt increase away from the dunite. Thesefeatures are consistent with formation of the dunite dykes byinteraction of MORB peridotites with boninitic melts from whichthe chromitites were formed. Because the transition-zone dunitesare mineralogically and chemically identical to those formedby such melt–rock reaction, we infer that they are ofsimilar origin. The Luobusa ultramafic rocks originally formedas MORB-source upper mantle, which was subsequently trappedas part of a mantle wedge above a subduction zone. Hydrous meltsgenerated under the influence of the subducted slab at depthmigrated upward and reacted with the cpx-bearing harzburgitesto form the dunite dykes. The modified melts ponded in smallpockets higher in the section, where they produced podiformchromitites with dunite envelopes. At the top of the mantlesection, pervasive reaction between melts and harzburgite producedthe transition-zone dunites. KEY WORDS: melt–rock interaction; REE; PGE; hydrous melt; mantle; ophiolite; Tibet  相似文献   

Porosity–permeability relationships in Miocene carbonate platforms and slopes seaward of the Great Barrier Reef, Australia (ODP Leg 194, Marion Plateau)     

STEPHEN N. EHRENBERG  GREGOR P. EBERLI†  GREGOR BAECHLE† 《Sedimentology》2006,53(6):1289-1318

  相似文献   

Late-glacial ice advances in the western Italian Alps   总被引：1，自引：0，他引：1  

STEPHEN c. PORTER  GIUSEPPE OROMBELLI 《Boreas: An International Journal of Quaternary Research》1982,11(2):125-140

The extent of ice on the south side of the Mont Blanc massif during two late-glacial readvances is known primarily from the distribution of crystalline erratics on sedimentary and metasedimentary terrain, and from the distribution of end moraines and outwash remants. Similar dual moraine complexes are found elsewhere in upper Val d'Aosta and indicate that the pattern is regional in character. During the earlier readvance equilibrium-line altitudes were ca. 450 ± 50m lower than at present, whereas during the later readvance they were ca. 350 ± 50 m lower. The moraines, not yet closely dated, were deposited sometime after 14,200 ¹⁴C Years ago by which time Lago'd Alice near the margin of the würm moraine system at Ivrea had been deglaciated, and before 8400 years ago, at which time Rutor Glacier in upper Val d'Aosta was no larger than at present. The younger moraines are believed to correlate with Egesen moraines on the north side of the Alps, whereas the older set may either correlate with an early phase of the Egesen or with Daun advance.  相似文献   

Late winter distribution and abundance of sea-associated birds in south-western Greenland, the Davis Strait and southern Baffin Bay   总被引：1，自引：0，他引：1  

ANDERS MOSBECH  STEPHEN R. JOHNSON 《Polar research》1999,18(1):1-17

Sea-associated birds were recorded during systematic aerial surveys of marine mammals in south-western Greenland, the Davis Strait and southern Baffin Bay in March 1981, 1982, 1991, 1993 and in April 1990. Most surveys included the northern part of the south-west Greenland Open Water Area, which in most years lies between 62° and 67°N. but none of the area south of 63°N was surveyed. The bird data are generally semi-quantitative and provide information on distribution and relative abundance in different areas during different years, under different ice conditions.
In all years, regardless of ice conditons, large concentrations of king eiders Somateria spectabilis were found in water <50m deep on the shallow banks off south-west Greenland, especially on the northern portion of the Store Hellefiskebanke. We estimate that in 1981 and 1982 about 270000 king eiders overwintered on the banks off south-west Greenland.
Compared to king eiders, flocks of common eiders Somateria mollissima were considerably more dispersed. They were found mainly close to shore off south-west Greenland, where they were distributed along rocky coastlines.
A few thousands of large guillemots Uria spp. were recorded in the study area in March 1981, 1982, 1991 and 1993, but large numbers (>65000 birds) were recorded north of the south-west Greenland Open Water Area in April 1990. indicating that northward spring migration was underway at this time.  相似文献   

Book Review: NORTH SEA FORMATION WATERS ATLAS,Geological Society Memoir No. 15, eds. E.A. Warren and P.C. Smalley. The Geological Society,London, 1994. 208 pp. £199.00 (hardback,non-membership price), £149.00 (Geological Society fellows price). ISBN 1 897799 07 1     

STEPHEN CROWLEY 《Geological Journal》1997,32(2):192-193

  相似文献   

Book Reviews: Seismosaurus: The Earth Shaker     

STEPHEN K. DONOVAN 《Geological Journal》1996,31(3):299-299

  相似文献