Detrital zircon geochronology data, petrographic point count data and paleocurrent indicator data of Triassic turbidites in the Nanpanjiang Basin, South China

Triassic turbidites of the Nanpanjiang basin of south China represent the most expansive and voluminous siliciclastic turbidite accumulation in south China. The Nanpanjiang basin occurs at a critical junction between the southern margin of the south China plate and the Indochina, Siamo and Sibumasu plates to the south and southwest. The Triassic Yangtze carbonate shelf and isolated carbonated platforms in the basin have been extensively studied, but silicilastic turbidites in the basin have received relatively little attention. Deciphering the facies, paleocurrent indicators and provenance of the Triassic turbidites is important for several reasons: it promises to help resolve the timing of plate collisions along suture zones bordering the basin to the south and southwest, it will enable evaluation of which suture zones and Precambrian massifs were source areas, and it will allow an evaluation of the impact of the siliciclastic flux on carbonate platform evolution within the basin. Turbidites in the basin include the Early Triassic Shipao Formation and the Middle-Late Triassic Baifeng, Xinyuan, Lanmu Bianyang and Laishike formations. Each ranges upward of 700 m and the thickest is nearly 3 km. The turbidites contain very-fine sand in the northern part of the basin whereas the central and southern parts of the basin also commonly contain fine and rarely medium sand size. Coarser sand sizes occur where paleocurrents are from the south, and in this area some turbidites exhibit complete bouma sequences with graded A divisions. Successions contain numerous alternations between mud-rich and sand-rich intervals with thickness trends corresponding to proximal/ distal fan components. Spectacularly preserved sedimentary structures enable robust evaluation of turbidite systems and paleocurrent analyses. Analysis of paleocurrent measurements indicates two major directions of sediment fill. The northern part of the basin was sourced primarily by the Jiangnan massif in the northeast, and the central and southern parts of the basin were sourced primarily from suture zones and the Yunkai massif to the south and southeast respectively. Sandstones of the Lower Triassic Shipao Fm. have volcaniclastic composition including embayed quartz and glass shards. Middle Triassic sandstones are moderately mature, matrix-rich, lithic wackes. The average QFL ratio from all point count samples is 54.1/18.1/27.8% and the QmFLt ratio is 37.8/ 18.1/ 44.1%. Lithic fragments are dominantly claystone and siltstone clasts and metasedimentary clasts such as quartz mica tectonite. Volcanic lithics are rare. Most samples fall in the recycled orogen field of QmFLt plots, indicating a relatively quartz and lithic rich composition consistent with derivation from Precambrian massifs such as the Jiangnan, and Yunkai. A few samples from the southwest part of the basin fall into the dissected arc field, indicating a somewhat more lithic and feldspar-rich composition consistent with derivation from a suture zone Analysis of detrial zircon populations from 17 samples collected across the basin indicate: (1) Several samples contain zircons with concordant ages greater than 3000 Ma, (2) there are widespread peaks across the basin at 1800 Ma and 2500, (3) a widespread 900 Ma population, (3) a widespread population of zircons at 440 Ma, and (5) a larger population of younger zircons about 250 Ma in the southwestern part which is replaced to the north and northwest by a somewhat older population around 260-290 Ma. The 900 Ma provenance fits derivation from the Jiangnan Massif, the 2500, 1800, and 440 Ma provenance fits the Yunkai massif, and the 250 Ma is consistent with convergence and arc development in suture zones bordering the basin on the south or southwest. Early siliciclastic turbidite flux, proximal to source areas impacted carbonate platform evolution by infilling the basin, reducing accommodation space, stabilizing carbonate platform margins and promoting margin progradation. Late arrival, in areas far from source areas caused margin aggradation over a starved basin, development of high relief aggradational escarpments and unstable scalloped margins.

Radiogenic isotope record of Arctic Ocean circulation and weathering inputs of the past 15 million years

Lead (Pb), neodymium (Nd), and strontium (Sr) isotopic analyses were carried out on sediment leachates (reflecting the isotope composition of past seawater) and digests of the bulk residues (reflecting detrital continental inputs) of Integrated Ocean Drilling Program (IODP) Leg 302 and core PS2185 from the Lomonosov Ridge (Arctic Ocean). Our records are interpreted to reflect changes in continental erosion and oceanic circulation, driven predominantly by tectonic forcing on million-year timescales in the older (pre-2 Ma) part of the record and by climatic forcing of weathering and erosion of the Eurasian continental margin on thousand-year timescales in the younger (post-2 Ma) part. These data, covering the past ~15 Ma, show that continental inputs to the central Arctic Ocean have been more closely linked to glacial and hydrological processes occurring on the Eurasian margin than on continental North America and Greenland. The constancy of the detrital input signatures supports the early existence of an Arctic sea ice cover, whereas the major initiation of Northern Hemisphere glaciation at 2.7 Ma appears to have had little impact on the weathering regime of the Eurasian continental margin.

Weathering characteristics and lithology of samples from the Rauer Group, Antarctica, obtained in February/March 2007, and conducted with field support of POLARSTERN cruise ANT-XXIII/9

The presence of glacial sediments across the Rauer Group indicates that the East Antarctic ice sheet formerly covered the entire archipelago and has since retreated at least 15 km from its maximum extent. The degree of weathering of these glacial sediments suggests that ice retreat from this maximum position occurred sometime during the latter half of the last glacial cycle. Following this phase of retreat, the ice sheet margin has not expanded more than ~1 km seaward of its present position. This pattern of ice sheet change matches that recorded in Vestfold Hills, providing further evidence that the diminutive Marine Isotope Stage 2 ice sheet advance in the nearby Larsemann Hills may have been influenced by local factors rather than a regional ice-sheet response to climate and sea-level change.

Geological and geochemical characteristics of the Tersang gold deposit, Malaysia: implications for genesis and gold exploration

The Central gold belt of peninsular Malaysia comprises a number of gold deposits located in the east of the N-S striking Bentong-Raub Suture Zone. The Tersang gold deposit is one of the gold deposits in the gold belt and hosted in sandstone, rhyolite and breccia units. The deposit has an inferred resource of 528,000 ounces of gold. The geochronology of the Tersang deposit has been newly constrained by LA ICP-MS U-Pb zircon dating. The maximum depositional age of the host sedimentary rocks ranges from Early Carboniferous to Early Permian (261.5 ± 4.9 Ma to 333.5 ± 2.5 Ma) for the host sandstone and Late Triassic for the rhyolite intrusion (218.8 ± 1.7 Ma). Textural characteristics of pyrite have revealed five types including (1) Euhedral to subhedral pyrite with internal fracturing and porous cores located in the sandstone layers (pyrite 1); (2) Anhedral pyrite overgrowths on pyrite 1 and disseminated in stage 1 vein (pyrite 2); (3) Fracture-filled or vein pyrite located in stages 1 and 2 vein (pyrite 3); (4) Euhedral pyrite with internal fractures also located in stage 2 vein (pyrite 4); and (5) Subhedral clean pyrite located in the rhyolite intrusion (pyrite 5). Based on pyrite mapping and spot analyses, two main stages of gold enrichment are documented from the Tersang gold deposit. Gold in sandstone-hosted pyrite 1 (mean 4.3 ppm) shows best correlation with Bi and Pb (as evidenced on pyrite maps). In addition, gold in pyrite 3 (mean 8 ppm) located in stage 2 vein shows a good correlation with As, Ag, Sb, Cu, Tl, and Pb. In terms of gold exploration, we suggest that elements such as As, Ag, Sb, Cu, Tl, Bi, and Pb associated with Au may serve as vectoring tools in gold exploration. Our new geological, structural, geochemical and isotopic data together with mineral paragenesis, pyrite chemistry and ore fluid characteristics indicate that the Tersang gold deposit is comparable to a sediment-hosted gold deposit. Our new genetic model suggests deposition of the Permo-Carboniferous sediments followed by intrusion of rhyolitic magma in the Late Triassic. At a later stage, gold mineralisation overprinted the rhyolite intrusion and the sandstone.

Benthic foraminiferal stable isotope record from ODP Site 138-849 on the East Pacific Rise

Benthic foraminifer and delta13C data from Site 849, on the west flank of the East Pacific Rise (0°11 'N, 110°31'W; 3851 m), give relatively continuous records of deep Pacific Ocean stable isotope variations between 0 and 5 Ma. The mean sample spacing is 4 k.y. Most analyses are from Cibicides wuellerstorfi, but isotopic offsets relative to Uvigerina peregrina appear roughly constant. Because of its location west of the East Pacific Rise, Site 849 yields a suitable record of mean Pacific Ocean delta13C, which approximates a global oceanic signal. The ~100-k.y.-period climate cycle, which is prevalent in delta18O does not dominate the long-term delta13C record. For delta13C, variations in the ~400- and 41-k.y. periods are more important. Phase lags of delta13C relative to ice volume in the 41- and 23-k.y. bands are consistent with delta13C as a measure of organic biomass. A model-calculated exponential response time of 1-2 k.y. is appropriate for carbon stored in soils and shallow sediments responding to glacial-interglacial climate change. Oceanic delta13C leads ice volume slightly in the 100-k.y. band, and this suggests another process such as changes in continental weathering to modulate mean river delta13C at long periods. The delta13C record from Site 849 diverges from that of Site 677 in the Panama Basin mostly because of decay of 13C-depleted organic carbon in the relatively isolated Panama Basin. North Atlantic to Pacific delta13C differences calculated using published data from Sites 607 and 849 reveal variations in Pliocene deep water within the range of those of the late Quaternary. Maximum delta13C contrast between these sites, which presumably reflects maximum influx of high-delta13C northern source water into the deep North Atlantic Ocean, occurred between 1.3 and 2.1 Ma, well after the initiation of Northern Hemisphere glaciation. Export of high-delta13C North Atlantic Deep Water from the Atlantic to the circumpolar Antarctic, as recorded by published delta13C data from Subantarctic Site 704, appears unrelated to the North Atlantic-Pacific delta13C contrast. To account for this observation, we suggest that deep-water formation in the North Atlantic reflects northern source characteristics, whereas export of this water into the circumpolar Antarctic reflects Southern Hemisphere wind forcing. Neither process appears directly linked to ice-volume variations.

Clay mineral and heavy metal composition of sea-bed surface sediments and pre-Holocene sediment samples taken during POLARSTERN cruise ANT-XXIII/9

Surface mineralogical compositions and their association to modern processes are well known from the east Atlantic and south-west Indian sectors of the Southern Ocean, but data from the interface of these areas - the Prydz Bay-Kerguelen region - is still missing. The objective of our study was to provide mineralogical data of reference samples from this region and to relate these mineralogical assemblages to hinterland geology, weathering, transport and depositional processes. Clay mineral assemblages were analysed by means of X-ray diffraction technique. Heavy mineral assemblages were determined by counting of gravity-separated grains under a polarizing microscope. Results show that by use of clay mineral assemblages four mineralogical provinces can be subdivided: i) continental shelf, ii) continental slope, iii) deep sea, iv) Kerguelen Plateau. Heavy mineral assemblages in the fine sand fraction are relatively uniform except for samples taken from the East Antarctic shelf. Our findings show that mineralogical studies on sediment cores from the study area have the potential to provide insights into past shifts in ice-supported transport and activity and provenance of different water masses (e.g. Antarctic slope current and deep western boundary current) in the Prydz Bay-Kerguelen region.

Soil properties of western Wright Valley, Antarctica

Western Wright Valley, from Wright Upper Glacier to the western end of the Dais, can be divided into three broad geomorphic regions: the elevated Labyrinth, the narrow Dais which is connected to the Labyrinth, and the North and South forks which are bifurcated by the Dais. Soil associations of Typic Haplorthels/Haploturbels with ice-cemented permafrost at < 70 cm are most common in each of these geomorphic regions. Amongst the Haplo Great Groups are patches of Salic and Typic Anhyorthels with ice-cemented permafrost at > 70 cm. They are developed in situ in strongly weathered drift with very low surface boulder frequency and occur on the upper erosion surface of the Labyrinth and on the Dais. Typic Anhyorthels also occur at lower elevation on sinuous and patchy Wright Upper III drift within the forks. Salic Aquorthels exist only in the South Fork marginal to Don Juan Pond, whereas Salic Haplorthels occur in low areas of both South and North forks where any water table is > 50 cm. Most soils within the study area have an alkaline pH dominated by Na+ and Cl- ions. The low salt accumulation within Haplorthels/Haploturbels may be due to limited depth of soil development and possibly leaching.

Sr/Ca ratios of coccoliths from the Paleocene-Eocene Thermal Maximum

During the Paleocene-Eocene Thermal Maximum (PETM), rapid release of isotopically light C to the ocean-atmosphere system elevated the greenhouse effect and warmed temperatures by 5-7 °C for 105 yr. The response of the planktic ecosystems and productivity to the dramatic climate changes of the PETM may represent a significant feedback to the carbon cycle changes, but has been difficult to document. We examine Sr/Ca ratios in calcareous nannofossils in sediments spanning the PETM in three open ocean sites as a new approach to examine productivity and ecological shifts in calcifying plankton. The large heterogeneity in Sr/Ca among different nannofossil genera indicates that nannofossil Sr/Ca reflects primary productivity-driven geochemical signals and not diagenetic overprinting. Elevated Sr/Ca ratios in several genera and constant ratios in other genera suggest increased overall productivity in the Atlantic sector of the Southern Ocean during the PETM. Dominant nannofossil genera in tropical Atlantic and Pacific sites show Sr/Ca variations during the PETM which are comparable to background variability prior to the PETM. Despite acidification of the ocean there was not a productivity crisis among calcifying phytoplankton. We use the Pandora ocean box model to explore possible mechanisms for PETM productivity change. If independent proxy evidence for more stratified conditions in the Southern Ocean during the PETM is robust, then maintenance of stable or increased productivity there likely reflects increased nutrient inventories of the ocean. Increased nutrient inventories could have resulted from climatically enhanced weathering and would have important implications for burial rates of organic carbon and stabilization of climate and the carbon cycle.

(Table 2) Trace element composition of seleceted clast and matrix materials from ODP Site 125-786

Shipboard examination of volcanic and sedimentary strata at Site 786 suggested that at least four types of breccias are present: flow-top breccias, associated with cooling and breakup on the upper surface of lava flows; autobreccias, formed by in-situ alteration at the base of flows; fault-gouge breccias; and true sedimentary breccias derived from weathering and erosion of underlying flows. It is virtually impossible to assess the origin of breccia matrix by textural and mineralogical analyses alone. However, it is fundamental for our understanding of breccia provenance to determine the source component of the matrix material. Whether the matrix is uniquely clastderived can be determined by geochemical fingerprinting. Trace elements that are immobile during weathering and alteration do not change their relative abundances. A contribution to the matrix from any source with an immobile trace element signature different from that of the clasts would appear as a perturbation of the trace element signature of the matrix. Trace element analysis of bulk samples from clasts and matrix material in individual breccia units was undertaken in a fashion similar to that used by Brimhall and Dietrich (1987, doi:10.1016/0016-7037(87)90070-6) in analyzing soil provenance: (1) to help distinguish between sedimentary and volcanic breccias, (2) to determine the degree of mixing and depth of erosion in sedimentary breccias, and (3) to analyze the local provenance of the individual breccia components (matrix and clasts). The following elements were analyzed by X-ray fluorescence (XRF): Rb, Sr, Ba, U, Zr, Cu, Zn, Ti, Cr, and V. Of these elements, Zr and Ti probably exhibit truly immobile behavior (Humphris and Thompson, 1978, doi:10.1016/0016-7037(78)90222-3 ). The remaining elements are useful as a reference for the extent of compositional change during the formation of matrix material (Brimhall and Dietrich, 1987, doi:10.1016/0016-7037(87)90070-6).

Hydrogeological investigations in the upper Ouémé catchment in Benin, West Africa

The scope of this PhD thesis was the hydrogeological conceptualisation of the Upper Ouémé river catchment in Benin. The study area exceeds 14,500 km**2 and is underlain by a crystalline basement. At this setting the typical sequence of aquifers - a regolith aquifer at the top and a fractured bedrock aquifer at the bottom - is encountered, which is found in basement areas all over Africa and elsewhere in the world. The chosen regional approach revealed important information about the hydrochemistry and hydrogeology of this catchment. Based on the regional conceptual model a numerical groundwater flow model was designed. The numerical model was used to estimate the impact of climate change on the regional groundwater resources. This study was realised within the framework of the German interdisciplinary research project IMPETUS (English translation: "Integrated approach to the efficient management of scarce water resources in West Africa"), which is jointly managed by the German universities of Bonn and Cologne. Since the year 2000 the Upper Ouémé catchment was the principal target for investigations into the relevant processes of the regional water cycle. A first study from 2000 to 2003 (Fass, 2004, http://nbn-resolving.de/urn:nbn:de:hbz:5n-03849) focused on the hydrogeology of a small local catchment (~30 km**2). In the course of this thesis five field campaigns were underdone from the year 2004 to 2006. In the beginning of 2004 a groundwater monitoring net was installed based on 12 automatic data loggers. Manual piezometric measurements and the sampling of groundwater and surface water were realised for each campaign throughout the whole study area. Water samples were analysed for major ions, for a choice of heavy metals and for their composition by deuterium, oxygen-18 and tritium. The numerical model was performed with FEFLOW. The hydraulic and hydrochemical characteristics were described for the regolith aquifer and the bedrock aquifer. The regolith aquifer plays the role of the groundwater stock with low conductivity while the fractures of the bedrock may conduct water relatively fast towards extraction points. Flow in fractures of the bedrock depends on the connectivity of the fracture network which might be of local to subregional importance. Stable isotopes in combination with hydrochemistry proved that recharge occurs on catchment scale and exclusively by precipitation. Influx of groundwater from distant areas along dominant structures like the Kandi fault or from the Atacora mountain chain is excluded. The analysis of tritium in groundwater from different depths revealed the interesting fact of the strongly rising groundwater ages. Bedrock groundwater may possibly be much older than 50 years. Equilibrium phases of the silicate weathering products kaolinite and montmorillonite showed that the deeper part of the regolith aquifer and the bedrock aquifer feature either stagnant or less mobile groundwater while the shallow aquifer level is influenced by seasonal groundwater table fluctuations. The hydrochemical data characterised this zone by the progressive change of the hydrochemical facies of recently infiltrated rainwater on its flow path into deeper parts of the aquifers. Surprisingly it was found out that seasonal influences on groundwater hydrochemistry are minor, mainly because they affect only the groundwater levels close to the surface. The transfer of the hydrogeological features of the Upper Ouémé catchment into a regional numerical model demanded a strong simplification. Groundwater tables are a reprint of the general surface morphology. Pumping or other types of groundwater extraction would have only very local impact on the available groundwater resources. It was possible to integrate IMPETUS scenario data into the groundwater model. As a result it was shown that the impact of climate change on the groundwater resources until the year 2025 under the given conditions will be negligible due to the little share of precipitation needed for recharge and the low water needs for domestic use. Reason for concern is the groundwater quality on water points in the vicinity of settlements because of contamination by human activities as shown for the village of Dogué. Nitrate concentrations achieved in many places already alerting levels. Health risks from fluoride or heavy metals were excluded for the Upper Ouémé area.

Appendix A. Whole-rock major, trace and rare earth element analyses of the Ulubey volcanics, Appendix B. Analytical standards and detection limits for analyses

Collisional and post-collisional volcanic rocks in the Ulubey (Ordu) area at the western edge of the Eastern Pontide Tertiary Volcanic Province (EPTVP) in NE Turkey are divided into four suites; Middle Eocene (49.4-44.6 Ma) aged Andesite-Trachyandesite (AT), Trachyandesite-Trachydacite-Rhyolite (TTR), Trachydacite-Dacite (TD) suites, and Middle Miocene (15.1 Ma) aged Trachybasalt (TB) suite. Local stratigraphy in the Ulubey area starts with shallow marine environment sediments of the Paleocene-Eocene time and then continues extensively with sub-aerial andesitic to rhyolitic and rare basaltic volcanism during Eocene and Miocene time, respectively. Petrographically, the volcanic rocks are composed primarily of andesites/trachyandesites, with minor trachydacites/rhyolites, basalts/trachybasalts and pyroclastics, and show porphyric, hyalo-microlitic porphyric and rarely glomeroporphyric, intersertal, intergranular, fluidal and sieve textures. The Ulubey (Ordu) volcanic rocks indicate magma evolution from tholeiitic-alkaline to calc-alkaline with medium-K contents. Primitive mantle normalized trace element and chondrite normalized rare earth element (REE) patterns show that the volcanic rocks have moderate light rare earth element (LREE)/heavy rare earth element (HREE) ratios relative to E-Type MORB and depletion in Nb, Ta and Ti. High Th/Yb ratios indicate parental magma(s) derived from an enriched source formed by mixing of slab and asthenospheric melts previously modified by fluids and sediments from a subduction zone. All of the volcanic rocks share similar incompatible element ratios (e.g., La/Sm, Zr/Nb, La/Nb) and chondrite-normalized REE patterns, indicating that the basic to acidic rocks originated from the same source. The volcanic rocks were produced by the slab dehydration-induced melting of an existing metasomatized mantle source, and the fluids from the slab dehydration introduced significant large ion lithophile element (LILE) and LREE to the source, masking its inherent HFSE-enriched characteristics. The initial 87Sr/86Sr (0.7044-0.7050) and eNd (-0.3 to +3.4) ratios of the volcanics suggest that they originated from an enriched lithospheric mantle source with low Sm/Nd ratios. Integration of the geochemical, petrological and isotopical with regional and local geological data suggest that the Tertiary volcanic rocks from the Ulubey (Ordu) area were derived from an enriched mantle, which had been previously metasomatized by fluids derived from subducted slab during Eocene to Miocene in collisional and post-collisional extension-related geodynamic setting following Late Mesozoic continental collision between the Eurasian plate and the Tauride-Anatolide platform.