Varve Studies at Hector Lake, Alberta, Canada, and the Relationship Between Glacial Activity and Sedimentation

1986 ◽  
Vol 25 (2) ◽  
pp. 199-214 ◽  
Author(s):  
Eric M. Leonard

Glacial lake sedimentary records from Hector Lake in Banff National Park, Alberta, are examined with the aim of clarifying the relationship between glacial activity and outwash sedimentation. Rhythmic couplets in lake bottom sediments provide a method for accurate documentation and dating of recent sedimentation chronology, as analysis of 137Cs content indicates that the couplets are of annual periodicity (i.e., varves). A comparison of sedimentation rate records with recent regional glacial history indicates that high sedimentation rates of one to a few decades duration occur either during and immediately following periods of moraine deposition (ie, maximum ice stands) or during periods of rapid ice recession. Comparison of sedimentary records with somewhat longer term glacial and vegetation records indicates that sedimentation rate variations of several centuries duration closely parallel changes in upvalley ice extent. Over this time scale, high sedimentation rates occur during periods of relatively increased ice extent, low rates during periods of reduced ice extent. Within this general pattern, however, sedimentation rates may remain very high for nearly a century following maximum ice stands, due to the exposure of unstable glaciogenic deposits to fluvial reworking during ice recession.

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
I Nyoman Astawa ◽  
Deny Setiady ◽  
Priatin Hadi Wijaya ◽  
GM. Hermansyah ◽  
Mario Dwi Saputra

Gas biogenik dikenal sebagai gas rawa atau gas dangkal yang terbentuk dari bakteri metanogenik pada lingkungan anaerobik, khususnya pada daerah-daerah yang tingkat sedimentasinya sangat tinggi.Tujuan penelitian untuk mengetahui secara lebih rinci akan keberadaan gas tersebut di Delta Mahakam. Sungai tersebut merupakan sungai terbesar dan terpanjang di wilayah Kalimantan Timur dan mempunyai tingkat sedimentasi sangat tinggi. Daerah tersebut sangat cocok untuk penelitian indikasi gas biogenik. Hasil penelitian ditandai dengan terdapatnya kantong gas pada rekaman strata box, yang berada pada kedalaman lebih dari 10 (sepuluh) meter. Berdasarkan analisis laboratorium terhadap sampel gas yang diambil di bekas lubang bor adalah gas metan.Kata kunci: rekaman strata box, gas metan, Delta MahakamBiogenic gas known as swamp gas or shallow gas formed by methanogenic bacteria in anaerobic environments, especially in areas that the sedimentation rate is very high. The objective of the research is to find out more detail the occurrence of gas in the Mahakam Delta. The river is the largest and longest river in the East Kalimantan, and it has a very high sedimentation rate.  This area is very good to study the indication of the biogenic gas. The result is signed by gas pocket in the strata box records, whereas at a depth of more than 10 (ten) meters. Based on the laboratory analysis of the samples taken from the former gas borehole is a methane gas.Keywords: strata box records, methane gas, Mahakam Delta.


2021 ◽  
pp. 1-12
Author(s):  
Maximillian Van Wyk de Vries ◽  
Emi Ito ◽  
Mark Shapley ◽  
Guido Brignone

Abstract Annual resolution sediment layers, known as varves, can provide continuous and high-resolution chronologies of sedimentary sequences. In addition, varve counting is not burdened with the high laboratory costs of geochronological analyses. Despite a more than 100-year history of use, many existing varve counting techniques are time consuming and difficult to reproduce. We present countMYvarves, a varve counting toolbox which uses sliding-window autocorrelation to count the number of repeated patterns in core scans or outcrop photos. The toolbox is used to build an annually-resolved record of sedimentation rates, which are depth-integrated to provide ages. We validate the model with repeated manual counts of a high sedimentation rate lake with biogenic varves (Herd Lake, USA) and a low sedimentation rate glacial lake (Lago Argentino, Argentina). In both cases, countMYvarves is consistent with manual counts and provides additional sedimentation rate data. The toolbox performs multiple simultaneous varve counts, enabling uncertainty to be quantified and propagated into the resulting age-depth model. The toolbox also includes modules to automatically exclude non-varved portions of sediment and interpolate over missing or disrupted sediment. CountMYvarves is open source, runs through a graphical user interface, and is available online for download for use on Windows, macOS or Linux at https://doi.org/10.5281/zenodo.4031811.


1986 ◽  
Vol 26 (2) ◽  
pp. 218-231 ◽  
Author(s):  
Eric M. Leonard

Bottom sediments from three lakes in the Canadian Rocky Mountains were examined with the aim of evaluating the usefulness of downvalley sediment studies in reconstruction of Holocene glacial histories. Analyses of organic carbon and carbonate contents of core sediments provide information on changing sedimentation rate and changing relative importance of glacial and non-glacial sediment sources. Sedimentary histories of the three lakes are similar, suggesting that they record regional glacial/climatic forcing, rather than localized events, and thus that they may be useful in reconstructing Holocene glacial history. Lacustrine sediments indicate a period of high sedimentation rates and relatively large glacial sediment contribution prior to 7500-7000 yr B.P., with much reduced rates and decreased glacial sediment contribution between about 6000 and 4000 yr B.P., possibly interrupted by a brief period of increased glacial sediment output shortly after 5000 yr B.P. Sometime after 4000 yr B.P., sedimentation rates and glacial sediment output began to rise again, reaching approximately present levels by 2750-2650 yr B.P., and have not since returned to low mid-Holocene levels. In detail over the last 3000 yr there is some indication of a slight decrease in sedimentation rate for more than 1000 yr after about 2200 yr B.P. Sedimentation rates and glacial sediment input into all three lakes rose between about 900 and 750 yr B.P. and have remained very high since. If the lake sediments are interpreted as a proxy record of upvalley glacial activity, they allow the development of a glacial chronology which is at once generally consistent with, and more complete and easily datable than, the surficial glacial record.


2018 ◽  
Vol 24 (2) ◽  
pp. 73
Author(s):  
Subhan Subhan ◽  
La Ode Alirman Afu

ABSTRAKSedimentasi secara terus menerus menjadi masalah utama terumbu karang di perairan pesisir. Sebanyak 7 titik pengambilan sampel telah dilakukan di Teluk Kendari selama periode Juni - Oktober 2015. Penelitian ini bertujuan membuktikan adanya pengaruh laju sedimentasi terhadap rekrutmen karang baik dalam sebaran kelompok taksa dan ukuran koloni juvenil karang. Pengambilan sampel dengan transek kuadrat mengunakan alat selam SCUBA dilakukan untuk memperoleh data tentang rekrutmen karang. Sedangkan pengukuran laju sedimentasi menggunakan metode sediment trap. Hubungan antara laju sedimentasi dengan rekrutmen karang dianalisis dengan menggunakan analisis regresi sederhana. Hasil penelitian menunjukkan adanya hubungan linier negatif antara laju sedimentasi dan rekrutmen karang yang ditunjukkan dengan nilai koefisien korelasi r = -0.941. ABSTRACTSedimentation constantly becomes the major problem for coral reefs in coastal areas. There were seven sampling stations carried out in Kendari Bay between June and October 2015. The purpose of the present study was to confirm the effect of sedimentation rate on coral recruitment in the level of genus and size of the colony of coral’s juvenile. Sampling was collected using quadrant transect method with the help of SCUBA to obtain data on coral recruitment, while the sedimentation rates were measured using sediment trap method. The relationship between sedimentation rates and coral recruitment was analysed using regression linear. The results showed that there was negative relationship between sedimentation rates and coral recruitment with the coefficient correlation (r) = -0.941.              


Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Katalin Báldi ◽  
Csilla Balogh ◽  
Orsolya Sztanó ◽  
Krisztina Buczkó ◽  
Ilona Bedéné Muskó ◽  
...  

Although the ecosystem transforming impact of the invasive dreissenid mussels has been widely reported in short-to-mid time scale studies, little is known about the contribution of the spent shells to sediments accumulating on the lake bottom. The question whether the shell production significantly reduces the lifespan of the lake by increasing sedimentation rate is particularly interesting in those shallow lakes where the calcium supply is sufficient to maintain the high mussel biomass production permanently, and where the alkaline water does not favor shell dissolution. Lake Balaton, a large calcareous, shallow lake in Central Europe invaded by dreissenids (Dreissena polymorpha, Dreissena rostriformis bugensis), provides an ideal testing ground for this scenario. Therefore, we made calculations based on recent population abundance datasets (2000–2018), estimated the whole habitable, hard surface coastline and the muddy bottom of the pelagic area which is also gradually becoming inhabited by D. r. bugensis, using high resolution aerial photographs and analyzing seismic sections. We created four scenarios: (1) if no dreissenids are present (applying basic sedimentation rate); (2) if D. r. bugensis had not been introduced to the lake (only D. polymorpha); (3) if D. r. bugensis occupies the hard surfaces of the coastline (the current dominant situation); (4) if D. r. bugensis colonizes the entire lake bottom (a probable future model). Different sedimentation rates obtained from the literature were used to model the filling of Lake Balaton. The shell production of the new invader, D. r. bugensis can shorten the lake’s lifespan by one to two-thirds, depending on the model, and whether the mussel density currently observed at the shoreline is extended to the whole lake bottom. Attention is called to shallow calcareous lakes with low pre-invasion sedimentation rates in which the shell contribution of invasive mollusks has the potential to shorten lifespan.


2018 ◽  
Vol 5 (1) ◽  
pp. 44 ◽  
Author(s):  
I Putu Ranu Fajar Maharta ◽  
I Gede Hendrawan ◽  
Yulianto Suteja

Benoa Bay is one of the unique ecosystems on the island of Bali because it is a shallow estuary area and has an ecosystem that is important for the waters of the mangrove ecosystem and seagrass. In recent years, Benoa Bay has been reported to have undergone siltation due to sedimentation. However, there has not been much scientific study of the sedimentation rate occurring in Benoa Bay. The study of sedimentation will provide an overview of the rate of sedimetation in the study area. Numerical modeling is one of the most commonly used methods to describe hydrodynamic processes in waters, which are the main drivers of the process of movement of pollutants in waters such as waste, sediment, and others. Thus, the study of sedimentation rate, either spatially or temporally, needs to be done in the waters of Benoa Bay using numerical modeling. The results of this study show that sedimentation rates in Benoa Bay have a minimum value of 1.08x10-6 and a maximum of 24.88 kg/m2/day with an average of 0.57 kg/m2/day. High sedimentation rates occur in the western part of the bay, on the river route, and in the northern part of the bay, between Serangan Island and Mertasari beach. Areas that potentially experience silting in Benoa Bay include the southern port of Benoa Harbor which reaches 0.23 m/year, the waters north of Serangan Island reaching 0.008 m/year, and the area close to the estuary which reaches 0.35 m/year.


2019 ◽  
Vol 3 (2) ◽  
pp. 117-137
Author(s):  
Mustaqim Makki

Zakat merupakan salah satu sendi pokok ajaran Islam. Urgensi zakat yang merupakan anjuran agama Islam untuk menunaikan zakat dan memberikannya kepada yang berhak dengan ketentuan mencapai nishabnya, (kadar minimum harta tertentu) mempunyai nilai sangat signifikan dalam kehidupan manusia. Seorang insan yang sarat akan segala permasalahan pada fitrahnya menuntut untuk selalu berinteraksi kepada sesama, baik berupa materi maupun non materi. Zakat merupakan maliyah ijtima’iyyah yang mengandung nilai-nilai filantropi yang sangat tinggi, karena ketika mengaplikasikan kewajiban zakat kita telah membantu sesama serta mengurangi kesenjangan yang disebabkan beberapa sifat manusia diantaranya adalah sifat kikir, dengki dan iri hati. Menguatnya kembali harapan banyak kalangan terhadap implementasi filantropi Islam, baik dalam bentuk zakat, infak, sedekah, dan wakaf, memiliki keterkaitan erat dengan kondisi bangsa yang belum sepenuhnya bangkit dari keterpurukan sebagai dampak dari krisis ekonomi yang berkepanjangan. Kondisi ini berakibat kesenjangan penguasaan perekonomian antar warga negara menjadi kian lebar. Pada saat itulah, ziswaf (zakat, infak, sedekah, dan wakaf) kembali dilirik dan diharapkan menjadi alternatif solusi terhadap problem kemiskinan umat. Manusia sebagai khalifah fil ardh dalam Al Qurán menekankan muatan fungsional yang harus diemban oleh manusia dalam melaksanakan tugas-tugas kesejarahan dalam kehidupannya di muka bumi. Kaitan dengan konsep tersebut, ada dua fungsi manusia. Pertama: Manusia sebagai hamba (ábid), dituntut untuk sukses menjalin hubungan secara vertikal dalam hal ini hubungannya dengan ketuhanan (Teologis). Kedua adalah manusia sebagai khalifah, dituntut untuk sukses menjalin hubungan secara horizontal dalam hal ini hubungan terhadap manusia.Kata kunci: tafsir ayat zakat, filantropi, ekonomi keummatanAbstract:Zakat is one of the main points of Islamic teachings. The urgency of zakat which is suggested by Islam to fulfill and give it to those who are referred to with the provisions to reach their nishab, (minimum level of certain assets) has a very significant value in human life. A person who is full of all problems in his/her natural demands will always get interaction with other people, either material or non-material. Zakat is maliyah ijtima’iyyah which contains very high philanthropic values, because when applying the obligation of zakat we have helped others and reduced the gaps caused by some human traits including miser, jealousy and envy. The reinforcement of the expectations (estimation) from any levels on the implementation of Islamic philanthropy, which in the form of zakat, donation, alms and endowments, has a close relationship with the condition of the country that has not fully risen from bad economic adversity due to economic crisis. This condition causes a widening of the economic mastery among the citizens. At that moment, ziswaf (zakat, infaq, alms, and waqf) was again given a serious attentition and expected to be an alternative solution to the problem of poverty among citizens. Humans as khalifah fil ardh in the Qur'an emphasize the functional content that must be carried by humans in carrying out historical tasks in their lives on earth. In accordance with this concept, there are two human functions. First: Humans as servants (ábid), are required to succeed in establishing a vertical relationship in this case the relationship with God (Theological). Second, humans as caliphs, are required to succeed in establishing horizontal relationships in this case the relationship to humans.


Author(s):  
Evi Rosita ◽  
Siti Nurnaningrum

There are about 2.8 million incident of perineal rupture in maternal physiological labor. In 2050,it is estimated that the incidence of perineal rupture can be 6.3 million if it is not accompanied by a good midwifery care. In 2016, in Trawas, there was (89%) perineal rupture in primiparas and (57%) perineal rupture in multiparas. Perineal rupture incidences due to parity were still very high. This study aims to analyze the relationship between parity and the incidence of perineal rupture . It is quantitative studyusing a cross sectional approach, by using analysis of physiological maternity women  medical record data from January to April 2017 of 130 peoplein Trawas Public Health Center, Mojokerto Regency.The dataanalysis used was Chi - Square , indicated by p value = 0,000 with ɑ = 0,05. It means that the value of p <ɑ, so H1 is accepted. It can be concluded that there is a relationship between parity and the incidence of perineal rupture on physiological maternity women in Trawas Public Health Center,Mojokerto Regency. Midwives can apply collaboration with patients and their families to have physical and psychologicalpreparation with an alternative of hypnobirthing methods.


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