Annual Review of Earth and Planetary Sciences
0084-6597
1545-4495
Mỹ
Cơ quản chủ quản: ANNUAL REVIEWS , Annual Reviews Inc.
Lĩnh vực:
Astronomy and AstrophysicsSpace and Planetary ScienceEarth and Planetary Sciences (miscellaneous)
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Thông tin về tạp chí
The Annual Review of Earth and Planetary Sciences, in publication since 1973, covers significant developments in all areas of earth and planetary sciences, from climate, environment, and geological hazards to the formation of planets and the evolution of life.
Các bài báo tiêu biểu
THE QUALITY OF THE FOSSIL RECORD: Populations, Species, and Communities ▪ Abstract Paleontologists have always been concerned about the documentary quality of the fossil record, and this has also become an important issue for biologists, who increasingly look to accumulations of bones, shells, and plant material as possible ways to extend the time-frame of observation on species and community behaviors. Quantitative data on the postmortem behavior of organic remains in modern environments are providing new insights into death and fossil assemblages as sources of biological information. Important findings include: 1. With the exception of a few circumstances, usually recognizable by independent criteria, transport out of the original life habitat affects few individuals. 2. Most species with preservable hardparts are in fact represented in the local death assemblage, commonly in correct rank importance. Molluscs are the most durable of modern aquatic groups studied so far, and they show highest fidelity to the original community. 3. Time-averaging of remains from successive generations and communities often prevents the detection of short-term (seasons, years) variability but provides an excellent record of the natural range of community composition and structure over longer periods. Thus, although a complex array of processes and circumstances influences preservation, death assemblages of resistant skeletal elements are for many major groups good to excellent records of community composition, morphological variation, and environmental and geographic distribution of species, and such assemblages can record temporal dynamics at ecologically and evolutionarily meaningful scales.
Tập 24 Số 1 - Trang 433-464 - 1996
Application of Light Hydrocarbons in Natural Gas Geochemistry of Gas Fields in China Light hydrocarbons (LHs) are an important component of natural gas whose chemical and isotopic compositions play a vital role in identifying gas genetic type, thermal maturity, gas–gas correlation, gas–source correlation, migration direction and phase, and secondary alterations (such as evaporative fractionation, biodegradation, and thermochemical sulfate reduction) experienced by the gas pool. Through review of geochemical research into LHs over recent decades, and analysis of chemical and isotopic compositions of LHs of gases and condensates from more than 40 gas fields in China, we present an overview of the genetic mechanisms of LHs and the impacts of various factors on their geochemical compositions. The primary objectives of this review are to demonstrate the application of LH chemical and isotopic composition characteristics to gas geochemistry research and to assess the applicability and reliability of geochemical identification diagrams and parameters for determining gas genetic types, maturity, source, secondary alteration, and migration direction and phase. ▪ Three main genetic mechanisms are proposed for the formation of light hydrocarbons: thermal decomposition, catalytic decomposition of organic matter, and microbial action. ▪ Chemical and isotopic compositions of light hydrocarbons with different carbon numbers and/or structures can be used to identify the genetic types and maturity of natural gas. ▪ Content ratios and carbon isotopes of characteristic light hydrocarbons are good indicators for gas–gas and gas–source correlations. ▪ Secondary alterations (evaporative fractionation, biodegradation, thermochemical sulfate reduction) and migration of gas can be indicated by chemical and isotopic compositions of light hydrocarbons.
Tập 50 Số 1 - Trang 13-53 - 2022
BEDROCK RIVERS AND THE GEOMORPHOLOGY OF ACTIVE OROGENS ▪ Abstract Bedrock rivers set much of the relief structure of active orogens and dictate rates and patterns of denudation. Quantitative understanding of the role of climate-driven denudation in the evolution of unglaciated orogens depends first and foremost on knowledge of fluvial erosion processes and the factors that control incision rate. The results of intense research in the past decade are reviewed here, with the aim of highlighting remaining unknowns and suggesting fruitful avenues for further research. This review considers in turn (a) the occurrence and morphology of bedrock channels and their relation to tectonic setting; (b) the physical processes of fluvial incision into rock; and (c) models of river incision, their implications, and the field and laboratory data needed to test, refine, and extend them.
Tập 32 Số 1 - Trang 151-185 - 2004
Mercury Isotopes in Earth and Environmental Sciences Virtually all biotic, dark abiotic, and photochemical transformations of mercury (Hg) produce Hg isotope fractionation, which can be either mass dependent (MDF) or mass independent (MIF). The largest range in MDF is observed among geological materials and rainfall impacted by anthropogenic sources. The largest positive MIF of Hg isotopes (odd-mass excess) is caused by photochemical degradation of methylmercury in water. This signature is retained through the food web and measured in all freshwater and marine fish. The largest negative MIF of Hg isotopes (odd-mass deficit) is caused by photochemical reduction of inorganic Hg and has been observed in Arctic snow and plant foliage. Ratios of MDF to MIF and ratios of 199 Hg MIF to 201 Hg MIF are often diagnostic of biogeochemical reaction pathways. More than a decade of research demonstrates that Hg isotopes can be used to trace sources, biogeochemical cycling, and reactions involving Hg in the environment.
Tập 42 Số 1 - Trang 249-269 - 2014
Himalayan Metamorphism and Its Tectonic Implications The Himalayan range exposes a spectacular assemblage of metamorphic rocks from the mid- and deep crust that have fostered numerous models of how the crust responds to continental collisions. Recent petrogenetically based petrologic and geochronologic studies elucidate processes with unprecedented resolution and critically test models that range from continuum processes to one-time events. The pronounced metamorphic inversion across the Main Central Thrust reflects continuum thrusting between ca. 15 and 20 Ma, whereas exposure of ultrahigh-pressure rocks in northwestern massifs and syntaxis granulites reflects singular early (≥45 Ma) and late (≤10 Ma) exhumation events. Multiple mechanisms including wedge collapse and flow of melt-weakened midcrust are debated to explain pressure-temperature trajectories, patterns of thinning, and thermal overprinting. A geochronologic revolution is under way in which spatially resolved compositions and ages of accessory minerals are combined in a petrogenetically valid context to recover specific temperature-time points and paths. Combined chemical and chronologic analysis of monazite is now well established and titanite is particularly promising, but recent zircon data raise questions about anatectic rocks and their use for investigating tectonism.
Tập 42 Số 1 - Trang 381-419 - 2014
BED MATERIAL TRANSPORT AND THE MORPHOLOGY OF ALLUVIAL RIVER CHANNELS The morphology of an alluvial river channel is the consequence of sediment transport and sedimentation in the river. Morphological style is determined chiefly by the caliber and quantity of sediment delivered to the channel, although modulated by channel scale. Yet the relations between sediment transport and river morphology have received only limited, qualitative attention. In this review, the problem is studied by defining sediment transport regimes on the basis of the Shields number, a nondimensional measure of the capacity of the channel to move sediment of a given caliber. The problem is also approached from an inverse perspective by which the quantity and character of sediment deposits are used to infer details about the variation of sediment transport and sedimentation along a channel. Coupling the two approaches establishes a basis to gain new insights into the origins of alluvial channel morphology.
Tập 34 Số 1 - Trang 325-354 - 2006