Addition reactions, 488 amphiboles

In sediments and the maflc portion of the subducted crust, all of the reactions involving hydrous phases and carbonates involve solid solutions whose compositions depend on the bulk composition, in addition to pressure and temperature. Different bulk compositions cause different phase compositions and thus cause reactions to shift in P-T space, i.e., to start shallower or deeper. In peridotites, amphibole and to some extent chlorite are controlled by continuous and discontinuous reactions however, the other volumetrically important hydrous phases (e.g., brucite, serpentine, talc, and phase A ) in altered harzburgites display a relatively restricted compositional range, at least compared to those present in mafic eclogites. As a result, breakdown reactions of hydrous phases in harzburgites are dominated (in a first approximation) by discontinuous reactions, and take place over a restricted depth range of only a few kilometers. 

In addition to its role in catabolism, the citric acid cycle also plays an important role in cellular anabolism, or biosynthetic reactions. Many of the citric acid cycle intermediates are precursors for the s)mthesis of amino acids and macromolecules required by the cell. A pathway that functions in both catabolic and anabolic reactions is called an amphibolic pathway. 

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