Palaeogeography, Palaeoclimatology, Palaeoecology
Time-Specific Facies: the color and texture of biotic events 特集
Chemical Geology
1. Paleoproductivity and paleoredox conditions during late Pleistocene accumulation of laminated diatom mats in the tropical West Pacific
Zhifang Xiong, Tiegang Li, Thomas Algeo, Qingyun Nan, Bin Zhai, Bo Lu
► LDM was deposited under sulfidic–anoxic conditions with suboxic bottom waters. ► BSR occurred in an open, sulfate-unlimited system. ► Pyrite formation was limited by organic matter rather than reactive Fe. ► Elevated export productivity rather than later ventilation resulted in reducing conditions during LDM formation. ► Sediment lamination as an indicator of anoxic bottom water conditions must be approached cautiously.
2. Using the 87Sr/86Sr of modern and paleoseep carbonates from northern Cascadia to link modern fluid flow to the past
C. Joseph, M.E. Torres, R.A. Martin, B.A. Haley, J.W. Pohlman, M. Riedel, K. Rose
►87Sr/86Sr depletion in pore fluids and carbonates near seafloor at Barkley Canyon ► Similar87Sr/86Sr depletion identified in fluids/carbonates in an uncomformity 190mbsf at U1329 ►87Sr/86Sr depletion corresponds with Mn/Ca and δ13C enrichment, δ18O depletion to −12‰. ► Uplifted paleoseep carbonates have similar signal to Barkley Canyon, U1329 fluids and carbonates. ► Infer that fluids from our offshore sites are similar to fluids that sourced Oligocene paleoseeps
3. Brachiopods recording seawater temperature—A matter of class or maturation?
Maggie Cusack, Alberto Pérez Huerta, EIMF
► Secondary (S) layer fibres closest to primary (P) layer are isotopically light. ► Oxygen isotopic equilibrium is indicated by grey box. ► Oxygen isotopic equilibrium is achieved in innermost fibres of secondary (S) layer. ► δ18O of mature shell innermost fibres is an accurate seawater temperature proxy.
4. Accurate and precise quantification of major and trace element compositions of calcic–sodic fluid inclusions by combined microthermometry and LA-ICPMS analysis
Tobias U. Schlegel, Markus Wälle, Mathew Steele-MacInnis, Christoph A. Heinrich
► Na–Ca-dominated fluid inclusions (FI) determined by microthermometry and LA-ICPMS. ► Two melting temperatures are measured in each FI, to yield true NaCl concentration. ► Improved accuracy of LA-ICPMS analysis of FI containing CaCl2as major component ► CaCl2concentration in FI is more precisely found by microthermometry than LA-ICPMS. ► Accurate determination of Ca-conc. in FI hosted within Ca-bearing host minerals
5. Neodymium isotopic compositions of the standard monazites used in UThPb geochronology
Zhi-Chao Liu, Fu-Yuan Wu, Yue-Heng Yang, Jin-Hui Yang, Simon A. Wilde
► A technique for simultaneous determination of UThPb ages and SmNd isotopes. ► Twelve standard monazites and four natural samples were analyzed. ► Manangoutry and Namaqualand are fairly homogeneous in SmNd isotopic compositions. ► They are potential standards for simultaneous UPb age and SmNd isotopic analyses.
