(Table 1) Calcium carbonate content of boulder clays sampled along the baltic coast of Schleswig-Holstein, Germany

The carbonate contents in the boulder clay ('Geschiebemergel') of abrasion cliffs were investigated along the Baltic coast of Schleswig-Holstein, northern West Germany. The calcareous boulder clay and stratified drift in the cliffs are interbedded with compressed thrust sheets of Cretaceous limestone, Tertiary Tarras clay, and Eemian clay. According to chemical analyses of 173 boulder clay samples, the amount of carbonate varies mostly between 6 and 17%. Owing to the small number of samples no definite conclusion could be drawn on the distribution of Danish Cretaceous limestones in the boulder clay, nor on the different directions of movement of Weichselian glaciers.

Geochemistry on Yangla copper deposit, China

The Yangla copper deposit, situated in the middle section of Jinshajiang tectonic belt between Zhongza-Zhongdian block and Changdu-Simao block, is a representative and giant copper deposit that has been discovered in Jinshajiang-Lancangjiang-Nujiang region in recent years. There are coupled relationship between Yangla granodiorite and copper mineralization in the Yangla copper deposit. Five molybdenite samples yielded a well-constrained 187Re-187Os isochron age of 233.3±3 Ma, the metallogenesis is therefore slightly younger than the crystallization age of the granodiorite. S, Pb isotopic compositions of the Yangla copper deposit indicate that the ore-forming materials were derived from the mixture of upper crust and mantle, also with the magmatic contributions. In the late Early Permian, the Jinshajiang Oceanic plate was subducted to the west, resulting in the formation of a series of gently dipping thrust faults in the Jinshajiang tectonic belt, meanwhile, accompanied magmatic activities. In the early Late Triassic, which was a time of transition from collision-related compression to extension in the Jinshajiang tectonic belt, the thrust faults were tensional; it would have been a favorable environment for forming ore fluids. The ascending magma provided a channel for the ore-forming fluid from the mantle wedge. After the magma arrived at the base of the early-stage Yangla granodiorite, the platy granodiorite at the base of the body would have shielded the late-stage magma from the fluid. The magma would have cooled slowly, and some of the ore-forming fluid in the magma would have entered the gently dipping thrust faults near the Yangla granodiorite, resulting in mineralization.

Permeability measurements on sheared and unsheared samples from different IODP Holes of Leg 316 and from IODP Hole 315-C0001E and ODP Hole 190-1174B

At subduction zones, the permeability of major fault zones influences pore pressure generation, controls fluid flow pathways and rates, and affects fault slip behavior and mechanical strength by mediating effective normal stress. Therefore, there is a need for detailed and systematic permeability measurements of natural materials from fault systems, particularly measurements that allow direct comparison between the permeability of sheared and unsheared samples from the same host rock or sediment. We conducted laboratory experiments to compare the permeability of sheared and uniaxially consolidated (unsheared) marine sediments sampled during IODP Expedition 316 and ODP Leg 190 to the Nankai Trough offshore Japan. These samples were retrieved from: (1) The décollement zone and incoming trench fill offshore Shikoku Island (the Muroto transect); (2) Slope sediments sampled offshore SW Honshu (the Kumano transect) ~ 25 km landward of the trench, including material overriden by a major out-of-sequence thrust fault, termed the "megasplay"; and (3) A region of diffuse thrust faulting near the toe of the accretionary prism along the Kumano transect. Our results show that shearing reduces fault-normal permeability by up to 1 order of magnitude, and this reduction is largest for shallow (< 500 mbsf) samples. Shearing-induced permeability reduction is smaller in samples from greater depth, where pre-existing fabric from compaction and lithification may be better developed. Our results indicate that localized shearing in fault zones should result in heterogeneous permeability in the uppermost few kilometers in accretionary prisms, which favors both the trapping of fluids beneath and within major faults, and the channeling of flow parallel to fault structure. These low permeabilities promote the development of elevated pore fluid pressures during accretion and underthrusting, and will also facilitate dynamic hydrologic processes within shear zones including dilatancy hardening and thermal pressurization.

Calcareous nannofossils in ODP Hole 131-808C

ODP Leg 131 recovered nannofossil-bearing sediments from Site 808 in the Nankai Trough, western Pacific Ocean. Three holes were examined for nannofossils, 808A, 808B, and 808C. A total of 22 nannofossil events were recognized, of which 10 are used as zonal markers. The sediments recovered from Hole 808A (0-111.4 mbsf) contain Pleistocene nannofossil assemblages that are mostly well preserved. All samples from this hole were assigned to nannofossil Zone NN21. The nannofossil assemblages observed in Hole 808B (111.0-358.8 mbsf) are poorly to well preserved and were all assigned to the Pleistocene. The NN21/NN20 Boundary is placed at 230.7 ± 4.4 mbsf. Hole 808C was cored from 298.5 to 1327 mbsf and basalt was reached at 1289.9 mbsf. The sediments recovered range in age from the upper part of Zone NN20 of the Pleistocene to Zone NN5 of the middle Miocene and contain poorly to well-preserved nannofossil assemblages. The Pliocene/Pleistocene Boundary, marked by the FO Gephyrocapsa caribbeanica, was placed at 776.3 ±1.6 mbsf, and the Miocene/Pliocene Boundary is tentatively placed at 955.9 ±1.5 mbsf. The lowermost sediments above basement as well as a sediment sample intercalated between basalt flows are assigned to Zone NN5, with an age of approximately 15 Ma. Age estimates provided by nannofossils show that the sedimentation rate in the trench-fill deposits of the Nankai Trough was very high, 800-1350 m/m.y (0-0.46 Ma), whereas in the Shikoku Basin deposits (> 0.46 Ma), the sedimentation rate was much lower (24-200 m/m.y). These age estimates also provide an extrapolated age of approximately 15 Ma for the basaltic basement at Site 808.

Common depth points and associated geographic coordinates

Fluids in subduction zones can influence seismogenic behaviour and prism morphology. The Eastern Makran subduction zone, offshore Pakistan, has a very thick incoming sediment section of up to 7.5 km, providing a large potential fluid source to the accretionary prism. A hydrate-related bottom simulating reflector (BSR), zones of high amplitude reflectivity, seafloor seep sites and reflective thrust faults are present across the accretionary prism, indicating the presence of fluids and suggesting active fluid migration. High amplitude free gas zones and seep sites are primarily associated with anticlinal hinge traps, and fluids here appear to be sourced from shallow biogenic sources and migrate to the seafloor along minor normal faults. There are no observed seep sites associated with the surface expression of the wedge thrust faults, potentially due to burial of the surface trace by failure of the steep thrust ridge slopes. Thrust fault reflectivity is restricted to the upper 3 km of sediment and the deeper décollement is non-reflective. We interpret that fluids and overpressure are not common in the deeper stratigraphic section. Thermal modelling of sediments at the deformation front suggests that the deeper sediment section is relatively dewatered and not currently contributing to fluid expulsion in the Makran accretionary prism.

Geochemistry and ages of rock samples from Kirwanveggen, Antarctica

The basement of southern Kirwanveggen (western Dronning Maud Land) is formed by a SSW-dipping section consisting of (from SW to NE): migmatic gneisses; granitoid; low-grade/prograde meta-pelites, meta-psammites and meta-basalts (= "Polaris Formation"); ortho-gneiss; quartzite mylonite; Polaris Formation; quartzite mylonite; meta-turbidites. These units are (partly) separated by at least four SSW-dipping, NE to N directed major thrusts. Most probably, this thrust system is of Pan-African age. Towards north, the section is followed by the molasse-like Urfjell Group, deposited later than approx. 550 Ma and earlier than 450 Ma. Similarities with the Pan-African of the Shackleton Range (thrusting, molasse) led to the assumption, that the East/West Gondwana suture runs from the Shackleton Range towards Sor Rondane (eastern Dronning Maud Land) passing southern Kirwanveggen at its south-east.

Boron concentrations and isotope ratios of authigenic carbonates from the Oregon margin

Boron contents and boron, carbon and oxygen stable isotopes were determined for authigenic carbonates recovered from Ocean Drilling Program Leg 146, Oregon margin. Carbonate precipitates are the most widespread authigenic phase in the shallow accretionary wedge and carry chemical information about long-term variations in pore fluid origin and flow paths in the Cascadia subduction zone. Drilling the first ridge (toe area including the frontal thrust) and the second ridge (or Hydrate Ridge) of the prism demonstrated different fluid regimes, with higher B contents in the authigenic precipitates at the toe. The delta11B of 18 authigenic precipitates analysed ranges from 13.9 per mil to as high as 39.8 per mil, extending the upper range of previously reported carbonate delta11B values considerably. When related to the delta11B ratio of their parent solutions, these data are characteristic of fluid-related processes in accretionary prisms. Together with delta13C and delta18O, delta11B ratios of the carbonate concretions, nodules and crusts allow one to distinguish between precipitation influenced by (i) seawater, (ii) fluid reservoirs at different depth levels within the accretionary prism and (iii) cage water from dissociated gas hydrates, the latter possibly indicating a fluctuation of the bottom simulating reflector during most recent Earth's history. From this first systematic boron study on authigenic precipitates from an accretionary prism it is suggested that B contents of such carbonate crusts and concretions exceed those reported for other marine carbonates. Given the abundance of such precipitates at convergent margins, they represent a significant B sink in geochemical cycling. Isotopic compositions of the parent fluids to the carbonates mirror B chemistry of modern pore waters from convergent margins. The precipitates carry information of different subduction-related fluid processes over a certain period of time, and hence are a crucial tracer in the investigation of palaeo-fluid flow.

Whole rock and elements concentrations from IODP Hole 343-C0019E

The microstructures, mineralogy and chemistry of four representative samples collected from cores extracted from the Japan Trench during Integrated Ocean Drilling Project Expedition 343, the Japan Trench Fast Drilling Project (JFAST) have been studied using optical microscopy, TEM, SEM, XRF, XRD and microprobe analyses. The samples provide a transect from relatively undeformed marine sediments in the hanging wall, to the undeformed footwall material, crossing the thrust interface between the Pacific and North American plate, where the fault slipped during the March 2011 Tohoku-Oki earthquake. Our preliminary results suggest that the low strength of JFAST fault gouge material is caused by the high amount of clay minerals (~ 60% smectite, ~ 14 illite). Clay minerals in the décollement (gouge) sample are partly replaced by newly formed manganese oxide, which precipitated from hydrothermal fluids. Dauphine twins were found in quartz grains of the décollement sample suggesting local high stress possible during seismic loading. Other microstructures cannot be assigned unambiguously to co-seismic or a-seismic faulting processes. The observed scaly clay fabric is consistent with observations in many other plate-boundary fault zones. Significant grain size reduction was found in the fault (decollement) zone sample. But a change in lithology of the fault material cannot be ruled out. Microstructures typical for a-seismic deformation like dissolution-precipitation features (e.g. dissolved grain boundaries, mineral alteration) occur in all JFAST core samples, but more frequently in the décollement sample.