Clay mineralogy of the Peru continental margin and adjacent Nazca plate: Implications for provenance, sea level changes, and continental accretion

1981 ◽  
pp. 545-568 ◽  
Author(s):  
Victor J. Rosato ◽  
L. D. Kulm
Keyword(s):  
Sea Level ◽  
Continental Margin ◽  
Clay Mineralogy ◽  
Sea Level Changes ◽  
Nazca Plate ◽  
Continental Accretion

Dynamics and evolution of continental margin clinoform systems

2020 ◽  
Author(s):  
Gerben de Jager ◽  
Dicky Harishidayat ◽  
Benjamin Emmel ◽  
Ståle Emil Johansen
Keyword(s):  
Sea Level ◽  
Continental Margin ◽  
Water Depth ◽  
Large Scale ◽  
Barents Sea ◽  
Source Rocks ◽  
Sea Level Changes ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Geological Processes

<p>Clinoforms are aquatic sedimentary features commonly associated with strata prograding from a shallower water depth into a deeper water depth. They are very sensitive to changes in water depth, rapidly moving along the shelf in response to sea level changes.  By reconstructing the initial clinoform geometry of buried clinoforms, an estimate of the paleo water depth (PWD) can be made. When this is done for several subsequent clinoform sets the amounts and rates of bathymetric changes can be calculated.</p><p>Here we present a novel approach to estimate clinoform parameters and depositional depths for continental margin clinoforms using seismic reflections, wellbore and biostratigraphy data. Seismic interpretation of three relatively east-west regional full-stack seismic reflection data from the continental margin of the western Barents Sea revealed twelve Late Cenozoic horizons. The clinoform shapes have been restored by removing the effects of compaction and flexural isostasy (backstripping). This includes the effects of glacial/interglacial scenarios on horizons with strong glaciomarine seismic indications.</p><p>Based on the reconstructed clinoform geometries we use empirical relationships from literature between clinoform geometry and depositional depth to estimate PWD values. In these analyses it is possible to estimate the PWD of the upper rollover point and the toe point by measuring the bottomset height, foreset height and topset height. A sensitivity analysis study has also been done on several different scenarios, varying elastic thickness, decompaction and net to gross ratio. Comparison with biostratigraphic water depth estimates indicate that PWD estimates revealed from clinoform parameters give reliable results.</p><p>Any mismatch between the backstripped PWD values and the PWD values derived from the clinoform geometry can then be attributed to geological processes not included in the backstripping process. Among others, these could be explained by rifting, thermal effects in the lithosphere, faulting or eustatic sea level changes. This allows the quantification of the magnitude of these large-scale crustal processes through time.</p><p>We will demonstrate that this method can further constrain the PWD on the continental margin clinoform system and thus can help to improve the understanding of the interplay between sedimentary processes and large-scale crustal processes. Furthermore, the PWD estimates will be a reliable input for further analysis of source-to-sink and stratigraphic forward modeling studies as well as reservoir and source rocks prediction on the petroleum development and exploration.</p><p> </p>

Cenozoic sea-level and cryospheric evolution from deep-sea geochemical and continental margin records

2020 ◽  
Author(s):  
Kenneth Miller ◽  
James Browning ◽  
W. John Schmelz ◽  
Robert Kopp ◽  
Gregory Mountain ◽  
...  
Keyword(s):  
Sea Level ◽  
Continental Margin ◽  
Ice Sheets ◽  
Late Eocene ◽  
Temperature Record ◽  
Early Eocene ◽  
Last Deglaciation ◽  
Sea Level Changes ◽  
Bottom Water Temperature ◽  
Continental Scale

<p>Cenozoic (past ~66 Myr) sea-level history reflects temperature changes and cryospheric evolution of the Earth from essentially ice-free conditions in the Early Eocene to bipolar ice sheets in the Quaternary. We derived a global mean sea level (GMSL) estimate for the Cenozoic using a new astronomically calibrated Pacific benthic foraminiferal δ<sup>18</sup>O splice from published records and a 2 Myr-smoothed Pacific bottom water temperature record based on published benthic foraminiferal Mg/Ca data. Our GMSL estimates are similar to sea-level estimates derived from “backstripping” (progressively accounting for compaction, loading and thermal subsidence) of cores from the mid-Atlantic U.S. continental margin. Peak global warmth, elevated GMSL, high CO<sub>2</sub>, and largely ice-free conditions occurred during the Early Eocene “Hothouse.” During the Middle-Late Eocene “Cool Greenhouse,” small ice sheets associated with lower atmospheric CO<sub>2</sub> drove sea-level changes. Continental-scale ice sheets began in the Oligocene “Icehouse” (ca. 34 Ma), a permanent East Antarctic ice sheet began in the middle Middle Miocene (ca. 12.8 Ma), and full, bipolar glaciation began in the Quaternary (ca. 2.55 Ma). The Last Glacial Maximum (20-27 ka) was the largest lowering of GMSL (~130 m) of the Mesozoic-Cenozoic and GMSL rise during last deglaciation (ca. 19-10 ka) exceeded 40-45 mm/yr.  Sea-level rise progressively slowed from 10 ka to 2 ka and was then at stillstand until late 19<sup>th</sup> to early 20<sup>th</sup> century when rates began to rise. Despite large uncertainties in proxies, our study reaffirms that throughout the Cenozoic, high long-term (10<sup>7</sup>-year scale) CO<sub>2</sub> was associated with warm climates and high sea levels.  However, sea level-change was dominated by periodic, astronomically controlled (10’s kyr-Myr scale) Milankovitch variations superimposed upon longer-term changes driven by CO<sub>2</sub>.</p>

Numerical modeling of icehouse and greenhouse sea-level changes on a continental margin: Sea-level modulation of deltaic avulsion processes

2020 ◽  
Vol 111 ◽  
pp. 807-814 ◽  
Author(s):  
Ashley D. Harris ◽  
Jacob A. Covault ◽  
Sarah Baumgardner ◽  
Tao Sun ◽  
Didier Granjeon
Keyword(s):  
Numerical Modeling ◽  
Sea Level ◽  
Continental Margin ◽  
Sea Level Changes

Paleozoic Sea-Level Changes in the Appalachian Basin: Washington, D.C., July 20–24, 1989

10.1029/ft354 ◽  
1989 ◽  
Author(s):  
John M. Dennison ◽  
Edwin J. Anderson ◽  
Jack D. Beuthin ◽  
Edward Cotter ◽  
Richard J. Diecchio ◽  
...  
Keyword(s):  
Sea Level ◽  
Appalachian Basin ◽  
Sea Level Changes
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