Has Earth ever been ice-free? Implications for glacio-eustasy in the Cretaceous greenhouse age using high-resolution sequence stratigraphy

2020 ◽  
Vol 133 (1-2) ◽  
pp. 243-252 ◽  
Author(s):  
Wen Lin ◽  
Janok P. Bhattacharya ◽  
Brian R. Jicha ◽  
Brad S. Singer ◽  
William Matthews

Abstract Controls on high-frequency sequences formed during super-greenhouse conditions in the Late Cretaceous Western Interior Seaway remain equivocal because of the active foreland basin tectonic setting and the lack of direct evidence of polar glaciations to support a glacio-eustatic origin. This paper quantifies eustatic sea-level changes based on high-resolution sequence stratigraphic analysis and improved chronometry of shallow marine deposits of the Late Cretaceous Gallup Sandstone in New Mexico, USA. Backstripping techniques remove tectonic and compactional subsidence and enable quantification of the magnitude of eustatic sea-level change, that allow evaluation of the dominant controls on the high-frequency sequences to resolve the role of orbitally controlled, climate-driven eustasy versus tectonics. Sixty-five parasequences, constituting 29 parasequence sets and 12 sequences are identified in the ∼1.2 m.y. duration of the Late Cretaceous Gallup system. New 40Ar/39Ar dating of bentonites constrains the durations of the individual parasequences, parasequence sets, and sequences, and that these match Milankovitch periodicity, indicating an orbital climate control. The magnitudes of sea-level changes between parasequences range between −28 m and +22 m, which are compatible with hypotheses of both aquifer and glacio-eustasy. Aquifer-eustasy predicts a reciprocal relationship between floodplain cycles and shallow marine sequences, such that aquifer drawdown and falling water tables should correlate to rising sea levels (highstands), whereas increased aquifer storage and rising water tables should correlate to falling sea levels (lowstands). Our preliminary observations show synchronous, versus reciprocal, relationships that may be more compatible with a glacio-eustatic origin. The results of this study support the hypothesis that the Cretaceous greenhouse was marked by high-frequency, low-amplitude glaciations driven by orbital climate cycles, but further work is required to evaluate the contribution of aquifer-eustasy.

2021 ◽  
Author(s):  
◽  
Glenn Richard Hughes

<p>The convergent tectonic setting of New Zealand has lead to the development of a series of anticlines and troughs resulting from folding and faulting of basement greywacke in southwest North Island. The most extensive of these is the Kairanga Trough spreading from the Horowhenua to the Manawatu, which lies between the uplifting Tararua Range and subsiding South Wanganui Basin. This trough was a major depocentre for fluvial and shallow marine strata during the Quaternary. By utilising a 280m deep borehole from the Kairanga Trough, this thesis investigates how climate and sea level variations affected sedimentation in the north Horowhenua District.   This borehole has recorded a near continuous record of climate and sea level change for the last 340ka. The lower part of the core is a marine sequence representing progressive infilling of the Kairanga Trough during 5th order (c.100ka) glacioeustatic fluctuations, which consequently produced 4 marine cyclothems. Transgressions and subsequent highstand periods are represented by shallow marine sediment, which were followed by fluvial aggradation during lowstand periods, then marine planation during subsequent transgressions. Cycle 1 developed during OIS 9 (340-300ka). Cycles 2 and 3 both formed during OIS 7 as a result of two closely spaced highstands centred around 245ka (OIS 7c) and 200ka (OIS 7a), which were separated by a period of lower sea level around 225ka (OIS 7b) that produced a disconformity. Cycle 4 formed during the Last Interglacial transgression (OIS 5e) and represents an incised valley fill. Progradation of a coastal strandplain and alluvial plain representing the latter stages of infilling of the Kairanga Trough with coastal and terrigenous sediment during the mid to late Last Interglacial and Glacial Periods is recorded in the sediment composing the top part of the borehole.</p>


2014 ◽  
Vol 152 (3) ◽  
pp. 400-428 ◽  
Author(s):  
HANNA MATYJA ◽  
KATARZYNA SOBIEŃ ◽  
LESZEK MARYNOWSKI ◽  
MARZENA STEMPIEŃ-SAŁEK ◽  
KRZYSZTOF MAŁKOWSKI

AbstractThe uppermost Famennian – lowermost Tournaisian interval has been analysed in detail using biostratigraphy, sedimentology, magnetic susceptibility and geochemistry in a reference section of the relatively shallow carbonate ramp environment within the Pomeranian Basin. High-resolution biostratigraphic study, based on miospores, allows recognition of the standard western Europeanlepidophyta–nitidus(LN) andverrucosus–incohatus(VI) zones, as well as theConvolutispora majorZone, a local Pomeranian equivalent of the European standardhibernicus–distinctus(HD) Zone. The sedimentary succession and specific phenomena recognized close to the Devonian/Carboniferous boundary, such as fluctuations in water column euxinia, wildfire evidence, relative sea-level changes and perturbations of the carbon cycle reflected by positive carbon excursions, display a pattern partly similar to that observed in many areas in Europe during the Hangenberg Event, although the Hangenberg Black Shale horizon is not developed here. These important microscale environmental perturbations were observed not only within the Famennian LN miospore Zone but in a wide interval between the LN and the lowermost localConvolutispora majormiospore zones ( = lower part of HD standard miospore Zone). It is still uncertain whether the recognized event(s) were connected solely with the Hangenberg Event, which was possibly complex and multi-phased as is sometimes suggested, or whether they represent a succession of regionally limited, post-Hangenberg events. This question needs to be further investigated on broader stratigraphic and geographical scales.


2021 ◽  
Author(s):  
◽  
Glenn Richard Hughes

<p>The convergent tectonic setting of New Zealand has lead to the development of a series of anticlines and troughs resulting from folding and faulting of basement greywacke in southwest North Island. The most extensive of these is the Kairanga Trough spreading from the Horowhenua to the Manawatu, which lies between the uplifting Tararua Range and subsiding South Wanganui Basin. This trough was a major depocentre for fluvial and shallow marine strata during the Quaternary. By utilising a 280m deep borehole from the Kairanga Trough, this thesis investigates how climate and sea level variations affected sedimentation in the north Horowhenua District.   This borehole has recorded a near continuous record of climate and sea level change for the last 340ka. The lower part of the core is a marine sequence representing progressive infilling of the Kairanga Trough during 5th order (c.100ka) glacioeustatic fluctuations, which consequently produced 4 marine cyclothems. Transgressions and subsequent highstand periods are represented by shallow marine sediment, which were followed by fluvial aggradation during lowstand periods, then marine planation during subsequent transgressions. Cycle 1 developed during OIS 9 (340-300ka). Cycles 2 and 3 both formed during OIS 7 as a result of two closely spaced highstands centred around 245ka (OIS 7c) and 200ka (OIS 7a), which were separated by a period of lower sea level around 225ka (OIS 7b) that produced a disconformity. Cycle 4 formed during the Last Interglacial transgression (OIS 5e) and represents an incised valley fill. Progradation of a coastal strandplain and alluvial plain representing the latter stages of infilling of the Kairanga Trough with coastal and terrigenous sediment during the mid to late Last Interglacial and Glacial Periods is recorded in the sediment composing the top part of the borehole.</p>


2009 ◽  
Vol 46 (6) ◽  
pp. 403-423 ◽  
Author(s):  
Karem Azmy ◽  
Denis Lavoie

The Lower Ordovician St. George Group of western Newfoundland consists mainly of shallow-marine-platform carbonates (∼500 m thick). It is formed, from bottom to top, of the Watts Bight, Boat Harbour, Catoche, and Aguathuna formations. The top boundary of the group is marked by the regional St. George Unconformity. Outcrops and a few cores from western Newfoundland were sampled at high resolution and the extracted micritic materials were investigated for their petrographic and geochemical criteria to evaluate their degree of preservation. The δ13C and δ18O values of well-preserved micrite microsamples range from –4.2‰ to 0‰ (VPDB) and from –11.3‰ to –2.9‰ (VPDB), respectively. The δ13Ccarb profile of the St. George Group carbonates reveals several negative shifts, which vary between ∼2‰ and 3‰ and are generally associated with unconformities–disconformities or thin shale interbeds, thus reflecting the effect of or link with significant sea-level changes. The St. George Unconformity is associated with a negative δ13Ccarb shift (∼2‰) on the profile and correlated with major lowstand (around the end of Arenig) on the local sea-level reconstruction and also on those from the Baltic region and central Australia, thus suggesting that the St. George Group Unconformity might have likely had an eustatic component that contributed to the development–enhancement of the paleomargin. Other similar δ13Ccarb shifts have been recorded on the St. George profile, but it is hard to evaluate their global extension due to the low resolution of the documented global Lower Ordovician (Tremadoc – middle Arenig) δ13Ccarb profile.


2021 ◽  
Author(s):  
Krešimir Ruić ◽  
Jadranka Šepić ◽  
Maja Karlović ◽  
Iva Međugorac

&lt;p&gt;Extreme sea levels are known to hit the Adriatic Sea and to occasionally cause floods that produce severe material damage. Whereas the contribution of longer-period (T &gt; 2 h) sea-level oscillations to the phenomena has been well researched, the contribution of the shorter period (T &lt;&amp;#160;2 h) oscillations is yet to be determined. With this aim, data of 1-min sampling resolution were collected for 20 tide gauges, 10 located at the Italian (north and west) and 10 at the Croatian (east) Adriatic coast. Analyses were done on time series of 3 to 15 years length, with the latest data coming from 2020, and with longer data series available for the Croatian coast. Sea level data were thoroughly checked, and spurious data were removed.&amp;#160;&lt;/p&gt;&lt;p&gt;For each station, extreme sea levels were defined as events during which sea level surpasses its 99.9 percentile value. The contribution of short-period oscillations to extremes was then estimated from corresponding high-frequency (T &lt; 2 h) series. Additionally, for four Croatian tide gauge stations (Rovinj, Bakar, Split, and Dubrovnik), for period of 1956-2004, extreme sea levels were also determined from the hourly sea level time series, with the contribution of short-period oscillations visually estimated from the original tide gauge charts.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Spatial and temporal distribution of contribution of short-period sea-level oscillations to the extreme sea level in the Adriatic were estimated. It was shown that short-period sea-level oscillation can significantly contribute to the overall extremes and should be considered when estimating flooding levels.&amp;#160;&lt;/p&gt;


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