A depth coincidence between the lanthanide tetrad effect maximum and the oxic/anoxic interface at the CariacoTrench off the Venezuelan coast.

Masuda, Akimasa; Shimoda, Junji; Ikeuchi, Yoshihiro

doi:10.2343/geochemj.32.275

Cited by 6 publications

(1 citation statement)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…PAAS-normalized REE pattern of Kallankurichchi limestones show M-and W-type tetrad effect in MREE and HREEs, which may result from enhanced aqueous complex of REE having empty or half-filled d orbitals (Patrick et al 2004). Maximum tetrad effects may be associated with the onset of anoxic or sub-oxic conditions (Masuda et al 1998). …”

Section: Tetrad Effect In Rare Earth Elementsmentioning

confidence: 98%

Depositional and post-depositional setting of Maastrichtian limestone, Ariyalur Group, Cauvery Basin, South India: a geochemical appraisal

Nagendra

Nagarajan

Bakkiaraj

et al. 2011

Carbonates Evaporites

View full text Add to dashboard Cite

Major, trace, REE, and stable isotopic composition of Maastrichtian limestones of Cauvery Basin were studied to decipher their depositional and post-depositional environment. The major oxides and trace elements concentration of these limestones were normalized using Post-Archean Australian Shale (PAAS) values. The concentration of CaO is having a significant enrichment, and MgO, K 2 O, Co, Ni, Cu, Zn, Pb, Ba, U, and Th are moderately depleted, whereas Sr and Na 2 O contents are relatively similar to the PAAS values. The PAAS-normalized REE ? Y pattern of Maastrichtian limestones display relatively uniform pattern among the compositionally different limestones: (1) enriched LREE (average Nd SN /Yb SN = 5.03 ± 0.92); (2) positive Ce anomaly (average 1.79 ± 0.16); (3) negative Gd SN /Gd* anomaly (average 0.52 ± 0.02); (4) low Y/Ho ratio (average Y/Ho = 0.14 ± 0.01). The average RREE contents in ferruginous, arenaceous, and biostromal limestones are 65, 64, and 52 ppm, respectively, which indicate that the mineralogical variation plays a major role in incorporation of RREE. The Kallankurichchi limestones have d 13 C values range from -3.2 to -1.1% PDB , and the d 18 O values range between -7.8 and -5.5% PDB . The negative d 13 C and d 18 O values and a moderate co-variation between d 13 C and d 18 O (r 2 = 0.35) indicate that the alteration of original isotopic composition is due to diagenesis. The positive Ce/Ce* confirms the clastic input into the system, and negative Mn* values and Th/U ratios (*0.29-1.4) in these limestones indicate their association with precipitation of carbonates in reducing (anoxic-dysoxic: Th/U B 2) conditions.

show abstract

Section: Tetrad Effect In Rare Earth Elementsmentioning

confidence: 98%