A record of post-glacial moraine deposition and tephra stratigraphy from Otokomi Lake, Rose Basin, Glacier National Park, Montana

2006 ◽  
Vol 43 (4) ◽  
pp. 447-460 ◽  
Author(s):  
David Matthew MacLeod ◽  
Gerald Osborn ◽  
Ian Spooner
Keyword(s):  
National Park ◽  
Drainage Basin ◽  
Younger Dryas ◽  
Glacier National Park ◽  
Before Present ◽  
Loss On Ignition ◽  
X Ray ◽  
The Core ◽  
Tephra Stratigraphy ◽  
Scale Data

The sedimentary record of Otokomi Lake, Glacier National Park, Montana, was studied to determine the age of an adjacent Crowfoot moraine. The presence of Mt. St. Helens Jy ash near the bottom of the longest percussion core limits drainage basin deglaciation to before 11 400 14C years before present (BP), although 14 100 BP is the estimated basal age of the core. Correlative shifts in loss on ignition, coarse (>1 mm) grain size, magnetic susceptibility, and X-ray gray-scale data at a depth of 185 cm are interpreted to be related to a sedimentary change in Otokomi Lake brought about by the deposition of the adjacent Crowfoot moraine. The estimated age of the moraine is 10 590 BP, which is within the Younger Dryas interval. This information supports the hypothesis that Crowfoot moraines represent a regional western North American response to Younger Dryas cooling.

scholarly journals Empirical evidence for stability of the 405-kiloyear Jupiter–Venus eccentricity cycle over hundreds of millions of years

2018 ◽  
Vol 115 (24) ◽  
pp. 6153-6158 ◽  
Author(s):  
Dennis V. Kent ◽  
Paul E. Olsen ◽  
Cornelia Rasmussen ◽  
Christopher Lepre ◽  
Roland Mundil ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
National Park ◽  
Numerical Solutions ◽  
Magnetic Polarity ◽  
Late Triassic ◽  
Before Present ◽  
The Core ◽  
Orbital Cycles ◽  
Chinle Formation ◽  
Earth’S Climate

The Newark–Hartford astrochronostratigraphic polarity timescale (APTS) was developed using a theoretically constant 405-kiloyear eccentricity cycle linked to gravitational interactions with Jupiter–Venus as a tuning target and provides a major timing calibration for about 30 million years of Late Triassic and earliest Jurassic time. While the 405-ky cycle is both unimodal and the most metronomic of the major orbital cycles thought to pace Earth’s climate in numerical solutions, there has been little empirical confirmation of that behavior, especially back before the limits of orbital solutions at about 50 million years before present. Moreover, the APTS is anchored only at its younger end by U–Pb zircon dates at 201.6 million years before present and could even be missing a number of 405-ky cycles. To test the validity of the dangling APTS and orbital periodicities, we recovered a diagnostic magnetic polarity sequence in the volcaniclastic-bearing Chinle Formation in a scientific drill core from Petrified Forest National Park (Arizona) that provides an unambiguous correlation to the APTS. New high precision U–Pb detrital zircon dates from the core are indistinguishable from ages predicted by the APTS back to 215 million years before present. The agreement shows that the APTS is continuous and supports a stable 405-kiloyear cycle well beyond theoretical solutions. The validated Newark–Hartford APTS can be used as a robust framework to help differentiate provinciality from global temporal patterns in the ecological rise of early dinosaurs in the Late Triassic, amongst other problems.

Lake core record of Grinnell Glacier dynamics during the latest Pleistocene deglaciation and the Younger Dryas, Glacier National Park, Montana, USA

2015 ◽  
Vol 84 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Nathan S. Schachtman ◽  
Kelly R. MacGregor ◽  
Amy Myrbo ◽  
Nora Rose Hencir ◽  
Catherine A. Riihimaki ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
National Park ◽  
Younger Dryas ◽  
Glacier National Park ◽  
Environmental Response ◽  
Glacial Retreat ◽  
The Holocene ◽  
Carbonate Concentration ◽  
Detrital Carbonate ◽  
The Last Glacial

Few records in the alpine landscape of western North America document the geomorphic and glaciologic response to climate change during the Pleistocene–Holocene transition. While moraines can provide snapshots of glacier extent, high-resolution records of environmental response to the end of the Last Glacial Maximum, Younger Dryas cooling, and subsequent warming into the stable Holocene are rare. We describe the transition from the late Pleistocene to the Holocene using a ~ 17,000-yr sediment record from Swiftcurrent Lake in eastern Glacier National Park, MT, with a focus on the period from ~ 17 to 11 ka. Total organic and inorganic carbon, grain size, and carbon/nitrogen data provide evidence for glacial retreat from the late Pleistocene into the Holocene, with the exception of a well-constrained advance during the Younger Dryas from 12.75 to 11.5 ka. Increased detrital carbonate concentration in Swiftcurrent Lake sediment reflects enhanced glacial erosion and sediment transport, likely a result of a more proximal ice terminus position and a reduction in the number of alpine lakes acting as sediment sinks in the valley.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

Abundance of coral-polyp-eating gastropods Drupella cornus in Bunaken National Park, Indonesia: indicating anthropogenic impact?

2013 ◽  
Vol 1 (1) ◽  
pp. 17
Author(s):  
Farnis B Boneka ◽  
N Gustaf F Mamangkey
Keyword(s):  
National Park ◽  
Anthropogenic Impact ◽  
Coral Cover ◽  
Human Intervention ◽  
Core Zone ◽  
The Core ◽  
Human Interventions ◽  
Coral Polyp ◽  
Intervention Zone ◽  
Drupella Cornus

Corallivorous gastropods, Drupella cornus are living in the Indo Pacific coral reefs. To assess the distribution of the snails at Bunaken National Park in Indonesia, a study has been conducted on three zones established in three main islands of the park: core, tourism, and exploitation zones. The zones represent degrees of human interventions in which the least intervention is for core zone, moderate for tourism zone and high for the exploitation zone. The results showed that degrees of human interventions are related to the density of snails where the least human intervention zone (the core zone) had low numbers of snails while the high human intervention (exploitation) zone had high numbers of snails. Three corals in the zones that were preferred by the snails were: Montipora spp., Acropora spp., and Porites spp. The numbers of snails living on the corals followed the percent of coral cover© Gastropod pemakan polip karang, Drupella cornus hidup di areal terumbu karang Indo-Pasifik. Untuk mengetahui distribusi dari siput di Taman Nasional Bunaken, sebuah studi telah dilakukan pada tiga zona yang ditetapkan di tiga pulau utama di taman nasional ini: zona inti, zona pariwisata, dan zona pemanfaatan. Hasil penelitian ini menunjukkan bahwa tinggi-rendahnya intervensi manusia berhubungan dengan kepadatan siput di mana zona yang memiliki intervensi terendah (zona inti) memiliki jumlah siput sedikit sementara zona dengan intervensi tertinggi (zone pemanfaatan) memiliki jumlah siput terbanyak. Tiga spesies karang di ketiga zona ini yang disukai oleh siput adalah Montipora spp., Acropora spp., and Porites spp. Jumlah siput yang hidup di karang mengikuti jumlah persen tutupan karang©

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