Kinematic behavior of southern Alaska constrained by westward decreasing postglacial slip rates on the Denali Fault, Alaska

Long-term slip rates for the Denali Fault in southern Alaska are derived using ^(10)Be cosmogenic radionuclide (CRN) dating of offset glacial moraines at two sites. Correction of ^(10)Be CRN model ages for the effect of snow shielding uses historical, regional snow cover data scaled to the site altitudes. To integrate the time variation of snow cover, we included the relative changes in effective wetness over the last 11 ka, derived from lake-level records and δ^(18)O variations from Alaskan lakes. The moraine CRN model ages are normally distributed around an average of 12.1 ± 1.0 ka (n = 22, ± 1σ). The slip rate decreases westward from ~13 mm/a at 144°49′W to about 7 mm/a at 149°26′W. The data are consistent with a kinematic model in which southern Alaska translates northwestward at a rate of ~14 mm/a relative to a stable northern Alaska with no rotation. This suggests progressive slip partitioning between the Denali Fault and the active fold and thrust belt at the northern front of the Alaska range, with convergence rates increasing westward from ~4 mm/a to 11 mm/a between ~149°W and 145°W. As the two moraines sampled for this study were emplaced synchronously, our suggestion of a westward decrease in the slip rate of the Denali Fault relies largely upon the measured offsets at both sites, regardless of any potential systematic uncertainty in the CRN model ages

Interactions Of Water-Soluble Zinc Porphyrin With Amino Acids

Equilibrium constants for replacement in aqueous solution of the axial ligand of tetrakis(4-N-methyl-pyridyl)porphinezinc(II) by a variety of amino acids at pH 9 have been determined spectrophotometrically. In addition, the equilibrium constant was determined for glycine as a function of pH. From the pH studies, it appears that the substitution of glycine of OH− at the Zn center is thermodynamically less favorable than for replacement of H₂O. Stabilization due to intramolecular non-covalent bonding between side-chains of several L-amino acids and the porphyrin macrocycle has also been observed

Constituants amers deBrucea amarissima structures des brucéines A, B et C

Evidence is presented for the structures (II a), (II b) and (II c) for the bruceines A, B and C, the bitter principles isolated from the seeds ofBrucea amarissima

Synthesis Of A Binuclear Copper(II) Water-Soluble Porphyrinic Complex Cu₂(tMPyP)(BiPy)

Synthesis of a binuclear copper(II) water-soluble porphyrinic complex, a potential restriction enzyme model, is described and preliminary data on its interactions with DNA are presented

Source parameters and tectonic origin of the 1996 June 1 Tianzhu (M<SUB>w</SUB>=5.2) and 1995 July 21 Yongden (M<SUB>w</SUB>=5.6) earthquakes near the Haiyuan fault (Gansu, China)

International audienceThe 1996 June 1 Tianzhu (Mw=5.2, Ms=4.9) and the 1995 July 21 Yongden (Mw=5.6, Ms=5.4) earthquakes are the two largest events recorded in the last 10 years between the 1990 October 20 Ms=5.8 and the recent 2000 June 6 Ms=5.6 earthquakes near the `Tianzhu seismic gap' on the Haiyuan fault in northeastern Tibet. We use frequency-time analysis (FTAN) to extract the fundamental modes of Love and Rayleigh waves from digital records. A joint inversion of their amplitude spectra and of P-wave first-motion polarities is then performed to calculate the source parameters (focal mechanisms, depths and seismic moments) of these two Ms~=5 earthquakes. Such a joint inversion is tested for the first time. We use IRIS and GEOSCOPE network records for period ranges of 20-40s for the former event and 35-70s for the latter. The inversion of the Tianzhu earthquake yields nodal planes with strike, dip and slip of 282°, 72° and 3° and 191°, 87° and 162°, respectively, a focal depth around 12km and a seismic moment of 0.56×1017Nm, consistent with the Harvard CMT calculation, and the alignment and depths of the aftershocks recorded by a local network. We propose two possible tectonic interpretations for this off-fault event. The solution for the Yongden earthquake is consistent with a thrust, with strike, dip and slip of 105°, 45° and 75°, respectively, a focal depth around 6km and a seismic moment of 2.4×1017Nm, also in agreement with the Harvard CMT mechanism, the distribution of the aftershocks recorded by a regional network, and the general tectonic setting that we refine