Marginal marine agglutinated foraminifera: affinities for mineral phases

Abstract. The major agglutinated constituents in test material of marginal marine foraminifera are identified as α-quartz and clay particles using complementary spectroscopic techniques. Electron dispersive scattering analysis, micro-laser Raman and Fourier transform infrared (FTIR) spectroscopic techniques revealed detail about elemental and mineral polymorph constituents in test walls. Additionally, FTIR identifies the existence of organic cements and lining materials in wall structures. Micro-laser Raman specifically characterized the titanium oxide mineral, anatase, as a distinctive fraction of agglutinate in Ammobaculites balkwilli Haynes. The mineral represents ≈10% of the test material, but comprises a minor component of the sediment and is identified in sediments only after heavy mineral separation. The enhanced concentration of anatase in the test of A. balkwilli suggests that there is a preferential selection for anatase. This provides further evidence that certain foraminifera can select grains specifically, which implies that there exists a selective mechanism and interaction between the organic (secreted) phases in the test walls and inorganic (grain surface) materials.