نتایج جستجو برای: diagenesis

تعداد نتایج: 1443  

Journal: :Archaeological and Anthropological Sciences 2009

2008
J. Timonen

Numerical micropermeametry is performed on three dimensional porous samples having a linear size of approximately 3 mm and a resolution of 7.5 μm. One of the samples is a microtomographic image of Fontainebleau sandstone. Two of the samples are stochastic reconstructions with the same porosity, specific surface area, and two-point correlation function as the Fontainebleau sample. The fourth sam...

2007
Kurt Schwehr Lisa Tauxe Neal Driscoll Homa Lee

[1] In clay-rich sediment, microstructures and macrostructures influence how sediments deform when under stress. When lithology is fairly constant, anisotropy of magnetic susceptibility (AMS) can be a simple technique for measuring the relative consolidation state of sediment, which reflects the sediment burial history. AMS can reveal areas of high water content and apparent overconsolidation a...

2017
Julie A. Terry Amir Sadeghian Jiangyong Hu

Dissolved oxygen is an influential factor of aquatic ecosystem health. Future predictions of oxygen deficits are paramount for maintaining water quality. Oxygen demands depend greatly on a waterbody’s attributes. A large sediment–water interface relative to volume means sediment oxygen demand has greater influence in shallow systems. In shallow, ice-covered waterbodies the potential for winter ...

1998
Matt Sponheimer Julia A. Lee-Thorp

An understanding of enamel diagenesis is necessary to ensure sound isotopic palaeodietary and palaeoenvironmental reconstructions. Although carbon isotope signals of browsing and grazing herbivores remain distinct in enamel even after millions of years, subtle alteration of isotopic signatures does occur. To better understand this change we analysed modern and fossil enamel from a number of Sou...

2004
CHRISTOPHER W. THOMAS COLIN M. GRAHAM ROBERT M. ELLAM ANTHONY E. FALLICK

New calcite Sr/Sr data for 47 limestones from the metamorphosed and deformed Neoproterozoic–Cambrian Dalradian Supergroup of Scotland and Ireland are used to identify secular trends in seawater Sr/Sr through the Dalradian succession and to constrain its depositional age. Dalradian limestones commonly have Sr .1000 ppm, indicating primary aragonite and marine diagenesis. Low Mn, Mn/Sr ,0.6, O an...

2006
Chen-Feng You Joris M. Gieskes Robert F. Chen Arthur Spivack Toshitaka Gamo

This study of the interstitial water concentration-depth distributions of iodide, bromide, boron, δ u B , and dissolved organic carbon, as represented by absorbance at 325 nm (yellow substance: YS) and laser-induced fluorescence (LIF), is a follow-up of the extensive shipboard program of interstitial water analysis during ODP Leg 131. Most of the components studied are associated with processes...

2006
R. K. STOESSELL

-Activity expressions are presented for a six end-member, regular solution, site-mixing model for chlorites. The end members are ideal 14-/~ chlorites for which experimental stability data are lacking. Estimates were made of the standard state 25~ and 1 bar molar 3rd law entropies, volumes, and the Maier-Kelley heat capacity coefficients. Experimental stability data from the literature for 14-A...

2010
Dawn Lavoie

The long-term goal of this study is to develop a better mechanistic and quantitative understanding of the effects of biologically-enhanced transport, mineralogy, sediment fabric, and particle surface chemistry on biogeochemical reactions occurring in coastal sediments. Specifically, we plan to provide quantitative expressions of biogeochemical processes from field and laboratory studies and to ...

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