$$^{40}Ar/^{39}Ar$$Age Calibration of the Litho- and Paleomagnetic Stratigraphies of the Ngorora Formation, Kenya (Dataset)
Paleomagnetic, rock magnetic, or geomagnetic data found in the MagIC data repository from a paper titled: $$^{40}Ar/^{39}Ar$$Age Calibration of the Litho- and Paleomagnetic Stratigraphies of the Ngorora Formation, Kenya
more »
« less
- Award ID(s):
- 2126298
- PAR ID:
- 10558618
- Publisher / Repository:
- Magnetics Information Consortium (MagIC)
- Date Published:
- Subject(s) / Keyword(s):
- Sedimentary Sediment Layer Tuffaceous Siltstone Tuffaceous Sandstone 9000000 14000000 Years BP
- Format(s):
- Medium: X
- Location:
- (Latitude:0.5; Longitude:35.5); (East Bound Longitude:35.5; North Bound Latitude:1.0; South Bound Latitude:0.0; West Bound Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5); (Latitude:1; Longitude:35.5)
- Right(s):
- Creative Commons Attribution 4.0 International
- Institution:
- Paleomagnetic Lab Scripps Institution Of Oceanography, UCSD, USA
- Sponsoring Org:
- National Science Foundation
More Like this
-
Mattoon, C.M.; Vogt, R.; Escher, J.; Thompson, I. (Ed.)The cross-section of the thermal neutron capture41Ar(n,γ)42Ar(t1/2=32.9 y) reaction was measured by irradiating a40Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived42K(12.4 h) β−daughter of42Ar. Our preliminary value of the41Ar(n,γ)42Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of42Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.more » « less
-
Abstract Androgen-independent prostate cancers, correlated with heightened aggressiveness and poor prognosis, are caused by mutations or deletions in the androgen receptor (AR) or expression of truncated variants of AR that are constitutively activated. Currently, drugs and drug candidates against AR target the steroid-binding domain to antagonize or degrade AR. However, these compounds cannot therapeutically access largely intrinsically disordered truncated splice variants of AR, such as AR-V7, that only possess the DNA binding domain and are missing the ligand binding domain. Targeting intrinsically disordered regions within transcription factors has remained challenging and is considered “undruggable”. Herein, we leveraged a cysteine-reactive covalent ligand library in a cellular screen to identify degraders of AR and AR-V7 in androgen-independent prostate cancer cells. We identified a covalent compound EN1441 that selectively degrades AR and AR-V7 in a proteasome-dependent manner through direct covalent targeting of an intrinsically disordered cysteine C125 in AR and AR-V7. EN1441 causes significant and selective destabilization of AR and AR-V7, leading to aggregation of AR/AR-V7 and subsequent proteasome-mediated degradation. Consistent with targeting both AR and AR-V7, we find that EN1441 completely inhibits total AR transcriptional activity in androgen-independent prostate cancer cells expressing both AR and AR-V7 compared to AR antagonists or degraders that only target the ligand binding domain of full-length AR, such as enzalutamide and ARV-110. Our results put forth a pathfinder molecule EN1441 that targets an intrinsically disordered cysteine within AR to destabilize, degrade, and inhibit both AR and AR-V7 in androgen-independent prostate cancer cells and highlights the utility of covalent ligand discovery approaches in directly targeting, destabilizing, inhibiting, and degrading classically undruggable transcription factor targets.more » « less
-
Abstract Deccan Traps flood basalt volcanism affected ecosystems spanning the end‐Cretaceous mass extinction, with the most significant environmental effects hypothesized to be a consequence of the largest eruptions. The Rajahmundry Traps are the farthest exposures (~1,000 km) of Deccan basalt from the putative eruptive centers in the Western Ghats and hence represent some of the largest volume Deccan eruptions. Although the three subaerial Rajahmundry lava flows have been geochemically correlated to the Wai Subgroup of the Deccan Traps, poor precision associated with previous radioisotopic age constraints has prevented detailed comparison with potential climate effects. In this study, we use new40Ar/39Ar dates, paleomagnetic and volcanological analyses, and biostratigraphic constraints for the Rajahmundry lava flows to ascertain the timing and style of their emplacement. We find that the lower and middle flows (65.92 ± 0.25 and 65.67 ± 0.08 Ma, ±1σsystematic uncertainty) were erupted within magnetochron C29r and were a part of the Ambenali Formation of the Deccan Traps. By contrast, the uppermost flow (65.27 ± 0.08 Ma) was erupted in C29n as part of the Mahabaleshwar Formation. Given these age constraints, the Rajahmundry flows were not involved in the end‐Cretaceous extinction as previously hypothesized. To determine whether the emplacement of the Rajahmundry flows could have affected global climate, we estimated their eruptive CO2release and corresponding climate change using scalings from the LOSCAR carbon cycle model. We find that the eruptive gas emissions of these flows were insufficient to directly cause multi‐degree warming; hence, a causal relationship with significant climate warming requires additional Earth system feedbacks.more » « less
-
Abstract We report40Ar‐39Ar step‐heating ages of Paleocene‐Eocene (P‐E) boundary impact spherules from Atlantic Margin coastal plain and open ocean sites. We test the hypothesis that the P‐E spherules are reworked from an earlier event (e.g., K‐Pg impact at ~66 Ma), which predicts a cooling age discordant from their depositional age of 55.93 ± 0.05 Ma at the P‐E boundary. Isochrons from the step‐heating analysis yield40Ar‐36Ar intercepts in excess of the modern in most cases, indicating that the spherules have excess radiogenic Ar (40Ar*), typical of impact glasses incompletely degassed before solidification. The weighted mean of the isochron‐corrected plateau age is 54.2 ± 2.5 Ma (1σ), and their isochron age is 55.4 ± 4.0 Ma, both indistinguishable from their P‐E depositional age, not supporting the K‐Pg reworking hypothesis. This is consistent with all other stratigraphic and geochemical evidence for an impact at the P‐E boundary and ejecta distribution by air fall.more » « less
An official website of the United States government
