Sedimentary and Source-to-Sink Evolution of Intracontinental Basins: Implications for tectonic and Climate Evolution in the Late Mesozoic (Southern Junggar Basin, NW China)

Sedimentary investigations, petrography, heavy mineral and conglomerate component analyses, and detrital zircon U-Pb geochronology were conducted to reconstruct the sedimentary and source-to-sink evolution of the Southern Junggar Basin, an intracontinental basin in the late Mesozoic. A paludal deltaic environment evolved into a fluvial environment, and abruptly prograded into alluvial fan and aeolian environments in the Late Jurassic, which was replaced by fan deltaic and lacustrine environments in the Early Cretaceous. Three source-to-sink systems were identified, according to different source-to-sink system features. In the northern piedmont of the Tianshan Orogenic Belt, the North Tianshan Orogenic Belt mainly provided sediments in the Late Jurassic. The North Tianshan and Central Tianshan Orogenic Belt both supplied sediments in the Early Cretaceous. In the northern piedmont of the Bogda Orogenic Belt, the Bogda Orogenic Belt was constantly the primary provenance, and the Tianshan Orogenic Belt also provided sediments. Sediment recycling occurred in the basin margin in the Late Jurassic and more metamorphic rocks were denudated in the Early Cretaceous. The source-to-sink system shrank in the Late Jurassic and expanded in the Early Cretaceous. This source-to-sink evolution and the conglomerates in the Kalazha Formation with seismite structures responded to the aridification in the Late Jurassic, the uplift of the Bogda and Tianshan Orogenic Belts in the Late Jurassic, and the exhumation of the Bogda and Tianshan Orogenic Belts in the Early Cretaceous.

Przekształcenie obszaru wysoczyzny lessowej pod wpływem gospodarczej działalności człowieka w neoholocenie (na wybranych przykładach z okolic Mozgawy, Ponidzie Pińczowskie)

The Mozgawa area, located in the Ponidzie Pińczowskie Region (SE part of the Nida River Basin), is a very good example of response of the natural environment to the progressive human impact. The research conducted there indicates that before the appearance of the first Neolithic farmers, the relief of the area was different to the modern one. Constant and intensive agricultural use of the loess plateau and the adjacent slopes (started in the Neolithic period some 5890±100 BP) led to the filling of the valley bottoms and local depressions with deluvial deposits, the thickness of which reaches up to 12 m. The deposition of these sediments and elevation of the surface level in the subordinate areas resulted in the creation of the Mozgawka River channel since the begining of the Roman Period. Formerly it was impossible (as it was within the depression) and the runoff was only through the karst system. Since that moment it has also started the accumulation of the alluvial fan, the progradation of which leads to the pushing of the Nida River channel towards the East.

Baseline bioavailable strontium and oxygen isotope mapping of the Adelaide Region

Strontium and oxygen isotopes provide a useful method for provenancing bioapaties, such as teeth and bone. In order for this approach to be successful, regional baseline bioavailable isotope data are required; however, few databases are currently available in Australia. This study measured stable oxygen and bioavailable strontium isotope ratios from low mobility fauna sampled from the major geological and physiographic provinces in Adelaide, South Australia in order to create a database for this region. Bioavailable strontium isotope ratios (87Sr/86Sr) obtained from the predominantly siliciclastic metasediments of the Neoproterozoic Adelaide Geosyncline have a range of 0.7122 ± 0.0001 to 0.7202 ± 0.0001. Cainozoic samples (dominantly terrestrial fluvial/lacustrine and marine carbonate sediments) from the Adelaide Plains have values in the range of 0.7098 ± 0.0002 to 0.7121 ± 0.0001. Samples from the alluvial fan sediments near the Eden-Burnside Fault at the boundary between these regions have values of 0.7131 ± 0.0001 to 0.7143 ± 0.0001. Stable oxygen isotope results range from 9.5 to 4.5‰ δ18OC (VPDB) and do not appear to vary systematically based on elevation, temperature, rainfall or humidity. These results demonstrate that strontium isotopes are potentially a useful tool for provenance studies within the Adelaide area. Oxygen is probably a more appropriate tool for discriminating seasonality rather than location within the study region. This research also suggests that rats are better suited for mapping strontium isoscapes than koalas, and that, while (non-systematic) offsets appear to exist between laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) and thermal ionisation mass spectrometry (TIMS) data, this effect is considerably less than the variation between geological provenances in the region.

The Role of New-Emerging Lands on Sources of Aeolian Sand Deposits Driven by Shrinking of the Urmia Salt Lake

Urmia Lake, the largest saline lake in Iran and the Middle East, is located in the northwest of Iran, has shrunk over the past decades. The reduced water level has increased the area of dry land around the lake allowing new environmental hazard such as sand dunes encroachment, particularly on the western side of the lake. There are five terrain types that could contribute sediment to the dunes, and it is the main aim of this research to identify the contributions to the dunes of each terrain type. Fifteen surface samples were collected from the five most erodible terrain types and eight samples were collected from the dunes both in downwind and upwind directions from the lake, and major element components were measured using X-ray fluorescence (XRF). According to the Besler classification, all samples are in the saline class. Also, the chemical index of alteration (CIA) values in all samples were less than 50, indicating weak weathering. Based on multivariate statistical analysis, suitable tracers were selected and were imported to the sourcing equations. Quantification of uncertainty and the creation of two new fingerprinting models for aeolian sediments based on both Bayesian and GLUE procedures were used. The highest proportion comes from the salty and puffy lands (44.2%) followed by salty polygon land (23.5%), clay-salty areas, puffy-flaky lands (7.01%), the terminus of the fine sandy alluvial fan (13.2%), and clay-salty abandoned lands (12.1%). It is concluded that if land managers use these results, they can more efficiently decrease the hazards posed by dune reactivation and migration though implementation of soil conservation on the affected lands around the dried lake.

The Role of Bedload Transport in the Development of a Proglacial River Alluvial Fan (Case Study: Scott River, Southwest Svalbard)

This study, which was conducted between 2010 and 2013, presents the results of direct, continuous measurements of the bedload transport rate at the mouth section of the Scott River catchment (NW part of Wedel-Jarlsberg Land, Svalbard). In four consecutive melt seasons, the bedload flux was analyzed at two cross-sections located in the lower reaches of the gravel-bed proglacial river. The transported bedload was measured using two sets of River Bedload Traps (RBTs). Over the course of 130 simultaneous measurement days, a total of 930 bedload samples were collected. During this period, the river discharged about 1.32 t of bedload through cross-section I (XS I), located at the foot of the alluvial fan, and 0.99 t through cross-section II (XS II), located at the river mouth running into the fjord. A comparison of the bedload flux showed a distinctive disproportion between cross-sections. Specifically, the average daily bedload flux QB was 130 kg day−1 (XS I) and 81 kg day−1 (XS II) at the individual cross-profiles. The lower bedload fluxes that were recorded at specified periods in XS II, which closed the catchment at the river mouth from the alluvial cone, indicated an active role of aggradation processes. Approximately 40% of all transported bedload was stored at the alluvial fan, mostly in the active channel zone. However, comparative Geomorphic Change Detection (GCD) analyses of the alluvial fan, which were performed over the period between August 2010 and August 2013, indicated a general lowering of the surface (erosion). It can be assumed that the melt season’s average flows in the active channel zone led to a greater deposition of bedload particles than what was discharged with high intensity during floods (especially the bankfull stage, effectively reshaping the whole surface of the alluvial fan). This study documents that the intensity of bedload flux was determined by the frequency of floods. Notably, the highest daily rates recorded in successive seasons accounted for 12–30% of the total bedload flux. Lastly, the multi-seasonal analysis showed a high spatio-temporal variability of the bedload transport rates, which resulted in changes not only in the channel but also on the entire surface of the alluvial fan morphology during floods.

Contributions to the Geology of Mt. Ruapehu, New Zealand

<p>During the passage of the lahar, shortly after 10 o'clock on Christmas Eve 1953, a portion of the Whangaehu River rail bridge at Tangiwai was demolished by a raging torrent of mud and boulders which originated from the Crater Lake of Mt. Ruapehu, nearly twenty miles distant. This mudflow, or lahar, damaged the railway bridge piers and the Wellington-Auckland express plunged into the torrent. As a result, one hundred and fifty-one people lost their lives. During tramping and ski-ing trips over the past five years the writer has become well acquainted with the National Park area. Close inspection of the Crater Lake was made on 1 January 1954, and again on 22 January. On the latter date the writer was accompanied by two chemists from the Chemistry Department, Victoria University College, and one from the Dominion Laboratory of the Department of Scientific and Industrial Research, who collected samples of the lake water. On 24 January, the Whangaehu River was followed from the Desert Road to where it emerges from a deep gorge on the lower slopes of Mt. Ruapehu. A number of braided channels were examined on the alluvial fan that extends east from the outlet gorge almost to the Desert Road. On the same day the scene of the disaster at Tangiwai was also inspected</p>

Contributions to the Geology of Mt. Ruapehu, New Zealand

<p>During the passage of the lahar, shortly after 10 o'clock on Christmas Eve 1953, a portion of the Whangaehu River rail bridge at Tangiwai was demolished by a raging torrent of mud and boulders which originated from the Crater Lake of Mt. Ruapehu, nearly twenty miles distant. This mudflow, or lahar, damaged the railway bridge piers and the Wellington-Auckland express plunged into the torrent. As a result, one hundred and fifty-one people lost their lives. During tramping and ski-ing trips over the past five years the writer has become well acquainted with the National Park area. Close inspection of the Crater Lake was made on 1 January 1954, and again on 22 January. On the latter date the writer was accompanied by two chemists from the Chemistry Department, Victoria University College, and one from the Dominion Laboratory of the Department of Scientific and Industrial Research, who collected samples of the lake water. On 24 January, the Whangaehu River was followed from the Desert Road to where it emerges from a deep gorge on the lower slopes of Mt. Ruapehu. A number of braided channels were examined on the alluvial fan that extends east from the outlet gorge almost to the Desert Road. On the same day the scene of the disaster at Tangiwai was also inspected</p>