Trace and rare earth elements as indicators of provenance and depositional environments of Lias cherts in Gumushane, NE Turkey

摘要: Abstract Trace elements and rare earth (REEs) of Lias-aged cherts in the Gumushane area were studied order to understand their origin depositional environment. Twenty three chert samples from five stratigraphic sections analysed by inductively coupled plasma-mass spectrometry, X-ray diffraction, mineralogical investigation. Lias study are microcrystalline, cryptocrystalline quartz, megaquartz depending on content. compared with PAAS, Co, Y, Th had stronger depletions sections, whereas V, Ni, Zr, Nb, Hf smaller depletions. The distribution Hf, Ta yields Zr/Hf, Zr/Ta Hf/Ta ratios (25/645, 37/665, 0.18/3, respectively) that differ those chondrites average upper continental crust, suggesting these likely non-detrital but sourced seawater. Th/U range 0.04 0.45 lower than crust (average: 3.9). have low total REE abundances PAAS chondrite-normalised plots. characterised a positive Eu anomaly 4.9) LREE-enrichment (La N /Yb  = average: 3.5). In addition, about one-half exhibit Ce (range: 0.25–2.58), chondritic Y/Ho values 3.3–60), (La/Ce) 1.8). trace element abundance indicate derived hydrothermal solutions, terrigenous sources, patterns show they probably deposited close margin.