GCP collection for corona satellite photographs: Issues and methodology

Use of high-resolution and historic CORONA satellite photographs for mapping and other purposes requires Ground Control Points (GCPs), as ephemeris data and image parameters are not available. However, the alterations in landscape in last 34 years (i.e., since the acquisition of these photographs) prevent identification and collection of large number of GCPs in the field. This paper presents a methodology for collection of GCPs for CORONA photographs. The advantages and limitations of the methodology are discussed. For a study site, situated in Siwaliks and Lower Himalayas, the GCPs were identified in CORONA photographs and their WGS84 coordinates were estimated through a process of datum transformation and georeferencing. Estimated GCP coordinates from the topo sheets and 2D and 3D views of photographs, helped in identifying the GCP locations in field, which were observed using DGPS. Investigations were carried out to relate Differential Global Positioning System (DGPS) accuracy with base line length and time of observation. Abase line of 350 km and half an hour observation were found appropriate to yield accuracy in GCP collection by DGPS method, which conforms to CORONA resolution of 3 m.     

Origins of archaeal tetraether lipids in sediments: Insights from radiocarbon analysis

Understanding the supply and preservation of glycerol dibiphytanyl glycerol tetraethers (GDGTs) in marine sediments helps inform their use in paleoceanography. Compound-specific radiocarbon measurements of sedimentary alkenones from multiple environments have been used to gain insight into processes that affect paleotemperature reconstructions. Similar analyses are warranted to investigate how analogous processes affecting GDGTs impact TEX₈₆ paleotemperatures. Here we present radiocarbon measurements on individual GDGTs from Bermuda Rise and Santa Monica Basin sediments and discuss the results in the context of previous studies of co-depositional alkenones and foraminifera. The ¹⁴C contents of GDGTs and planktonic foraminifera in Bermuda Rise are very similar, suggesting a local source; and TEX₈₆-derived temperatures agree more closely with foraminiferal temperatures than do temperatures. In contrast, GDGTs in Santa Monica Basin are depleted in ¹⁴C relative to both alkenones and foraminifera, and TEX₈₆ temperatures agree poorly with known surface water values. We propose three possible factors that could explain these results: (i) GDGTs may be labile relative to alkenones during advective transport through oxic waters; (ii) archaeal production deep in the water column may contribute ¹⁴C-depleted GDGTs to sediments; and (iii) some GDGTs also may derive from sedimentary archaeal communities. Each of these three processes is likely to occur with varying relative importance depending on geographic location. The latter two may help to explain why TEX₈₆ temperature reconstructions from Santa Monica Basin do not appear to reflect actual sea surface temperatures. Terrigenous GDGTs are unlikely to be major contributors to Bermuda Rise or Santa Monica Basin sediments, based on values of the BIT index. The results also indicate that the crenarchaeol regioisomer is governed by processes different from other GDGTs. Individual measurements of the crenarchaeol regioisomer are significantly depleted in ¹⁴C relative to co-occurring GDGTs, indicating an alternative origin for this compound that presently remains unknown. Re-examination of the contribution of crenarchaeol regioisomer to the TEX₈₆ index shows that it is a significant influence on the sensitivity of temperature reconstructions.     

Sediment Hosted Primary Tin Deposit Associated with Biotite Granite and Fault Zone at Gunung Paku, Klian Intan, Upper Perak, Malaysia

Gunung Paku near Klian Intan, Perak, is a primary tin deposit in Malaysia mined since 200 years ago, contributing 3–5% of tin ore concentrates previously, and recently over 70% of the Malaysian tin. Gunung Paku is located within the western Tin belt of Peninsular Malaysia associated with biotite granite (184–230 Ma) of the Main Range Granitoid which extends up to the southern part of Peninsular and Central Thailand. The primary tin mineralization style at the Gunung Paku is mainly associated with widespread occurrence of sheet-like quartz veining systems parallel to the strike of the host rocks and confined within a narrow N–S trending fault zone. The mineralization formed within a thick sequence of metasedimentry rock that belongs to the Baling Formation of Palaeozoic age. The host rock of weakly metamorphosed argillite generally experienced strong tropical weathering that resulted in a thick sequence of light grey to light brown oxidized profile. The mineralized veins range from simple quartz-cassiterite, quartz-tourmaline-cassiterite to complex quartz-cassiterite-polymetallic sulfide veins. Wall rock alterations at Gunung Paku are mainly characterized by the hypogene type alteration consisting of silicification, tourmalinization, chloritization, sericitization and kaolinization normally adjacent to mineralized quartz veins and brecciated-fault gouge zones. Pyrite, arsenopyrite, cassiterite, rutile, chalcopyrite, trippkeite (CuAsO4), scorodite, covellite and other secondary iron-oxyhydroxide are the common metallic minerals that accompanied the tin mineralization. Other minor occurrences include trace amounts of complex lead-bismuth-antimony-molybdenum bearing minerals.     

Comment on Gazi et al. (2020): Detecting Coral Reef Degradation on St. Martin’s Island,Bangladesh?

Ocean Science Journal - St. Martin’s Island is a small sedimentary island situated at the southernmost part of Bangladesh (20°37.6′ N and 92°19.3′ E). The island is...     

Calibration of local magnitude scale for Hindukush continental subduction zone

Hindukush is an active subduction zone where at least one earthquake occurs on daily basis. For seismic hazard studies, it is important to develop a local magnitude scale using the data of local seismic network. We have computed local magnitude scale for Hindukush earthquakes using data from local network belonging to Center for Earthquake Studies (CES) for a period of three years, i.e. 2015–2017. A total of 26,365 seismic records pertaining to 2,683 earthquakes with magnitude 2.0 and greater, was used with hypocentral distance less than 600 km. Magnitude scale developed by using this data comes to be M_L = logA + 0.929logr + 0.00298r – 1.84. The magnitude determined through formulated relation was compared with that of standard relation for Southern California and relation developed by the same authors for local network for Northern Punjab. It was observed that Hindukush region has high attenuation as compared to that of Southern California and Northern Punjab which implies that Hindukush is tectonically more disturbed as compared to the said regions, hence, seismically more active as well. We have calculated station correction factors for our network. Station correction factors do not show any pattern which probably owes to the geological and tectonic complexity of this structure. Standard deviation and variance of magnitude residuals for CES network determined using Hutton and Boore scale and scale developed in this study were compared, it showed that a variance reduction of 44.1% was achieved. Average of magnitude residuals for different distance ranges was almost zero which showed that our magnitude scale was stable for all distances up to 600 km. Newly developed magnitude scale will help in homogenization of earthquake catalog. It has been observed that b-value of CES catalog decreases when magnitude is calculated by using newly developed magnitude scale.     

十字石的原位高压X射线衍射研究

利用原位高压同步辐射能量色散X射线衍射技术,在室温下对采自新疆阿尔泰地区冲乎尔递增变质带的天然十字石进行高压晶体结构测定,测量的压力范围为0.0001~3.9GPa,共11组有效数据。实验表明,在实验压力范围内,随着压力的增加晶胞参数β值逐渐增大,表明了十字石的结构对称性随压力增加而有所降低;同时,在1.5~2.7GPa压力范围内,十字石的晶体结构也发生了改变。     

The problem,significance and implications for metamorphism of 60 million years of multiple phases of staurolite growth

Microstructural measurements of FIAs in staurolite reveal at least 3 periods of growth in the Proterozoic Colorado Front Range and 5 in the Paleozoic Western Maine. Dated monazite inclusions in staurolite have an absolute age of 1760±12 Ma (FIA 1), 1720±7 Ma (FIA 2), 1682±18 Ma (FIA 3) in Colorado, and 408±10 Ma (FIA 2), 388±8 Ma (FIA 3), 372±6 Ma (FIA 4), 352±4 Ma (FIA 5) in Maine, supporting the multiple periods of deformation and metamorphism indicated by the FIA succession in each region. Multiple phases of growth by similar reactions in the same as well as in diverse adjacent rocks in both regions suggest that PT and X are not the only factors controlling the commencement and cessation of metamorphic reactions. The FIAs preserved by the staurolite porphyroblasts indicate that the local partitioning of deformation at the scale of a porphyroblast was the eventual controlling factor on whether or not the staurolite forming reactions took place.     

Farm income,inequality, and poverty among farm families of a flood-prone area in Bangladesh: climate change vulnerability assessment

GeoJournal - This paper examines the farm income differences, income inequality of farm households, parameters of income variability that ascertain vulnerability levels, and cost-income variability...     

Multidimensional six-stage model for flood emergency response in schools: a case study of Pakistan

Natural Hazards - Children spend more than two-thirds of their total daytime in schools and becoming more persuasive in shielding them from potential hazards. Schools have a responsibility to...