Fluid inclusions significance

Schwarcz HP, Harmon RS, Thompson P, Ford DC (1976) Stable isotope studies of fluid inclusions in speleothems and their paleochmatic significance. Geochim Cosmochim Acta 40 657-665 Schwarcz HP, Rink WJ (2001) Dating methods for sediments of caves and rock shelters. Geoarchaeology 16 355-372... 

Improvements in analytical techniques have made possible reconstruction of ancient seawater composition from fluid inclusion trapped in marine halites. This has forced marine chemists to accept that the major ion composition has changed significantly— at least over the past 500 million years. Since marine halites older than 500 million years are rare, little is known about the major ion composition of seawater prior to the Phanerozoic eon. Thus, current modeling effiarts are directed at simulating changes in seawater composition over the Phanerozoic. 

Chlorine is the major anion in surface- and mantle-derived fluids. It is the most abundant anion in hydrothermal solutions and is the dominant metal complexing agent in ore forming environments (Banks et al. 2000). Despite its variable occurrence, chlorine isotope variations in natural waters conunonly are small and close to the chlorine isotope composition of the ocean. This is also true for chlorine from fluid inclusions in hydrothermal minerals which indicate no significant differences between different types of ore deposits such as Mississippi-Valley and Porphyry Copper type deposits (Eastoe et al. 1989 Eastoe and Guilbert 1992). 

Roedder, E. Results and Significance of Recent Fluid Inclusion Studies in Ore Deposits. 

Mineral hosted fluid inclusions contribute significantly to rubidium (20-25%) and to lesser extents the LILE budgets. 

PameU J., Honghan C., Middleton D., Haggan T., and Carey P. (2000) Significance of fibrous mineral veins in hydrocarbon migration fluid inclusion studies. J. Chem. Explor. 69-70, 623-627. 

The issues of initial Th and Pa are ones of accuracy, that is, how close the age determination is to the true age of the sample. A second concern, one that increases with the sample age, is the closed-system behavior of the U-Th-Pa decay chains. In general, older samples are more at risk because of the longer opportunity for diagenetic changes to have taken place. Speleothems with significant porosity are poorer candidates for closed-system behavior than are speleothems with dense fabrics. Fluid inclusions are a ubiquitous source of micron-scale fabric porosity but are generally isolated and thus do not translate to permeability with diagenetic implications. 

---