Core-Mantle equilibrium: Comments on a paper by R. Brett

Brett's arguments in the preceding paper are critically reviewed. It is concluded that the abundances of Ni, Co, Cu, Au and Pt in the upper mantle, the oxidation state of this region and the nature of the volatiles inferred to have been degassed from the upper mantle are not readily explained if the earth has accreted from a well mixed reservoir of preexisting metal and silicate particles in the solar nebula which were equilibrated within the earth prior to separation of the core. The data can be readily explained if it is assumed that the earth accreted inhomogeneously in a state which was initially out of overall chemical equilibrium and that equilibrium, although approached, was not finally achieved during core-segregation.     

Tectonic environments of ancient civilizations in the eastern hemisphere

The map distribution of ancient civilizations shows a remarkable correspondence with tectonic boundaries related to the southern margin of the Eurasian plate. Quantification of this observation shows that the association is indeed significant, and both historical records and archaeoseismological work show that these civilizations commonly suffered earthquake damage. Close association of ancient civilizations with tectonic activity seems to be a pattern of some kind. In the hope that dividing the civilizations into subsets might clarify the meaning of this relation, primary and derivative civilizations were compared. Derivative civilizations prove to be far more closely related to the tectonic boundaries. Similarly, the civilizations that endured the longest (and that have been described as most static) are systematically the farthest from plate boundaries. It is still unclear how the relation actually worked in ancient cultures, i.e., what aspects of tectonism promoted complexity. Linkages to water and other resources, trade (broadly construed), and societal response seem likely. Volcanism appears not to be involved. © 2008 Wiley Periodicals, Inc.     

如何解释陈家杖子金矿的铅同位素资料——与佘宏全等商榷

文章对赤峰地区陈家杖子、安家营子金矿床的铅同位素资料进行了综合分析,结果表明:①两个矿区硫化物的铅均为异常铅,其模式年龄无任何意义;②在常规Pb/Pb图解上,陈家杖子硫化物数据点趋势线是204Pb误差线,而不是来自两个不同源区的成矿物质混合作用所形成的混合线;③在常规Pb/Pb图解上,陈家杖子_安家营子硫化物数据点构成一条等时线,用此等时线计算,矿化物源区源岩的年龄(tr)为2·587Ga,与建平杂岩变质高峰期的年龄基本一致;④建平杂岩经历高级变质_分异作用之后,其μ值显著降低(μ3=6·03),变成了一套具代表性的下地壳岩石;⑤陈家杖子、安家营子金矿的成矿物质直接来自下地壳岩石———建平群变质岩,但它们至少经历了3个阶段的演化史。     

Comments on the paper of B. Lehmann: Molybdenum distribution in precambrian rocks of the Colorado mineral belt

Conclusions 1. Lehman lends me statements that I have not written.2. Interesting enough, the analytical data he presents do not allow, in effect, a molybdenum geochemical province in the Colorado mineral belt to be found. However, a better differentiation of rock types would be a useful improvement.3. Neither the available results, nor the (classic) model Proposed for the large Colorado deposits, are tests of the basic theorem. Furthermore, the model implies a heritage, a logical inference tightly associated with the theorem without being in its foundation.In my opinion, it is to be desired that our journals and learned societies become, at intervals, concerned about the history of our science and concepts in order to avoid drifts, not accuse B. Lehmann. I only believe he reads (in French) too quickly.     

Kinetic model options for interpretation of amino acid enantiomeric ratios in Quaternary mollusks: Comments on a paper by Kvenvoldenet al. (1979)

A comparison of linear (to D/L leucine of ca. 0.55) and non-linear (slowing of racemization rates by a factor of ca. 10 × after D/L leucine of ca. 0.25) model kinetics is presented in order to interpret amino acid enantiomeric ratio data in Holocene and Pleistocene marine mollusks from the Pacific coast of the United States. Linear model rate constants for well-dated Holocene and Pleistocene samples are not consistent with probable temperature histories or probable latitudinal differences in effective temperatures for these samples, using reasonable values for the activation energy of racemization. The non-linear model, with a much earlier transition from rapid to slow racemization rates, appears more consistent with available data.