Temporal patterns of barren intervals in the Phanerozoic

Paleobiology ◽  
2008 ◽  
Vol 34 (1) ◽  
pp. 155-161 ◽  
Author(s):  
Andrew B. Smith ◽  
A. J. McGowan
Keyword(s):  
Sedimentary Rock ◽  
Western Europe ◽  
Sedimentary Rocks ◽  
Direct Consequence ◽  
Rock Outcrop ◽  
Shallow Marine ◽  
Marine Diversity ◽  
Marine Realm ◽  
Weak Negative Correlation ◽  
Marine Sedimentary Rock

It has recently been argued that barren intervals of marine sedimentary rock are less common in the Cenozoic than in the Paleozoic, and that this arises as a direct consequence of widespread epeiric seas and the prevalence of dysaerobic conditions at such times. We show, using an independent and more direct measure of rock outcrop through time in western Europe, that barren marine sedimentary rocks do become less frequent toward the present, but that this is not linked to any epeiric-seas effect. The proportion of barren to fossiliferous rock outcrop correlates well with the inferred Phanerozoic marine diversity curve (although more so in the Paleozoic than in the post-Paleozoic), and shows no correlation or only a weak negative correlation with area over which the sediments have been deposited. We therefore concluded that the Phanerozoic trend in fossiliferousness most likely records the degree to which space is occupied in the shallow marine realm.

scholarly journals Cyclicity in the fossil record mirrors rock outcrop area

2005 ◽  
Vol 1 (4) ◽  
pp. 443-445 ◽  
Author(s):  
Andrew B Smith ◽  
Alistair J McGowan
Keyword(s):  
Recent Article ◽  
Sedimentary Rock ◽  
Western Europe ◽  
Rock Outcrop ◽  
Marine Diversity ◽  
Marine Fossils ◽  
History Of ◽  
Long Term Trends ◽  
Marine Sedimentary Rock

In a recent article, Rohde & Muller (Rohde & Muller 2005 Nature 434 , 208–210) identified a strong 62 Myr cyclicity in the history of marine diversity through the Phanerozoic. The data they presented were highly convincing, yet they were unable to explain what process might have generated this pattern. A significant correlation between observed genus-level diversity (after removal of long-term trends) and the amount of marine sedimentary rock measured at a surface outcrop in Western Europe is demonstrated. This suggests that cyclicity originates from long-term changes in sedimentary depositional and erosional regimes, and raises the strong possibility that the cyclicity apparent in the record of marine fossils is not a biological signal but a sampling signal.

scholarly journals Marine mammals through time: when less is more in studying palaeodiversity

2008 ◽  
Vol 276 (1658) ◽  
pp. 887-892 ◽  
Author(s):  
Felix G Marx
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
Sedimentary Rock ◽  
Rock Outcrop ◽  
Less Is More ◽  
Apparent Correlation ◽  
Mammal Evolution ◽  
Taxonomic Groups ◽  
Mammal Diversity ◽  
Marine Sedimentary Rock

The validity of biological explanations of patterns of palaeodiversity has been called into question owing to an apparent correlation of diversity with the amount of sedimentary rock preserved. However, this claim has largely been based on comprehensive estimates of global marine Phanerozoic diversity, thus raising the question of whether a similar bias applies to the records of smaller, well-defined taxonomic groups. Here, new data on European Caenozoic marine sedimentary rock outcrop area are presented and compared with European occurrences of three groups of marine mammals (cetaceans, pinnipedimorphs and sirenians). Limited evidence was found for a correlation of outcrop area with marine mammal palaeodiversity. In addition, similar patterns were identified in the cetacean and pinnipedimorph diversity data. This may point to the preservation of a genuine biological signal not overwhelmed by geological biases in the marine mammal diversity data, and opens the door to further analyses of both marine mammal evolution and geological bias in other small and well-defined groups of taxa.

scholarly journals Depositional facies and extent of the late Neogene Sandringham Sandstone in southern Victoria, Australia

2016 ◽  
Vol 128 (2) ◽  
pp. 7 ◽  
Author(s):  
Alfons H.M. VandenBerg
Keyword(s):  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Depositional Facies ◽  
Marine Origin ◽  
Shallow Marine ◽  
The Past ◽  
Late Neogene ◽  
Continuous Sheet ◽  
Southern Fringe ◽  
Western Victoria

The late Neogene sedimentary rocks in the Port Phillip region have in the past been subdivided into a lower shallow marine unit, Black Rock Sandstone, overlain by a fluvial unit, Red Bluff Sandstone. Re-examination of the type section of these units at Sandringham shows that it is entirely of paralic origin, with no evidence for fluvial deposition. Criteria for interpreting a shallow marine origin are sedimentary structures including a planar bedding style and swaley cross-stratification, and highly rounded clasts in conglomerates. Using these criteria it can be demonstrated that all named late Neogene sedimentary rock units in the Port Phillip region are paralic deposits, and that the same applies to the Hanson Plain Sand of the Port Campbell Embayment. Because these were deposited as a continuous sheet, the multiplicity of names used hitherto is not justified and should be unified under the single name Sandringham Sandstone. This formation was deposited on a strandplain that extends across western Victoria to the southern fringe of the Western Uplands. The same lateral continuity applies to the underlying Miocene marl formation, which is unified under the name Gellibrand Marl.

A metasedimentary source of gold in Archean orogenic gold deposits

Geology ◽  
2021 ◽  
Author(s):  
Iain K. Pitcairn ◽  
Nikolaos Leventis ◽  
Georges Beaudoin ◽  
Stephane Faure ◽  
Carl Guilmette ◽  
...  
Keyword(s):  
Sedimentary Rock ◽  
Sedimentary Rocks ◽  
Gold Deposits ◽  
Metamorphic Grade ◽  
Orogenic Gold ◽  
Metal Source ◽  
Main Metal ◽  
Metasedimentary Rocks ◽  
Orogenic Gold Deposits ◽  
Archean Orogenic Gold Deposits

The sources of metals enriched in Archean orogenic gold deposits have long been debated. Metasedimentary rocks, which are generally accepted as the main metal source in Phanerozoic deposits, are less abundant in Archean greenstone belts and commonly discounted as a viable metal source for Archean deposits. We report ultralow-detection-limit gold and trace-element concentrations from a suite of metamorphosed sedimentary rocks from the Abitibi belt and Pontiac subprovince, Superior Province, Canada. Systematic decreases in the Au content with increasing metamorphic grade indicate that Au was mobilized during prograde metamorphism. Mass balance calculations show that over 10 t of Au, 30,000 t of As, and 600 t of Sb were mobilized from 1 km3 of Pontiac subprovince sedimentary rock metamorphosed to the sillimanite metamorphic zone. The total gold resource in orogenic gold deposits in the southern Abitibi belt (7500 t Au) is only 3% of the Au mobilized from the estimated total volume of high-metamorphic-grade Pontiac sedimentary rock in the region (25,000 km3), indicating that sedimentary rocks are a major contributor of metals to the orogenic gold deposits in the southern Abitibi belt.

scholarly journals Vestige of The Ancient Estuarine of Cisaar Valley, Sumedang as One of the Pleistocene Fossil Bearing Site in West Jawa

2019 ◽  
Vol 8 (2) ◽  
pp. 65-80
Author(s):  
Unggul Prasetyo Wibowo ◽  
Anton Ferdianto ◽  
Nurul Laili ◽  
Dida Yurnaldi ◽  
Ruli Setiawan
Keyword(s):  
Depositional Environment ◽  
Sedimentary Rocks ◽  
Estuarine Environment ◽  
Shallow Marine ◽  
East Part ◽  
The Past ◽  
Braided Channel ◽  
Freshwater Mollusk ◽  
Past Data

Cisaar Valley is located on the east part of Sumedang Regency, West Jawa Province. It’s close to the boundary of Sumedang-Majalengka Regency. In this location the sandy and clay dominated sedimentary rocks are well exposed along the outcrops in the Cisaar Valley. These sedimentary rocks is inferred from Pliocene-Pleistocene deposits from Kaliwangu and Citalang Formation. Foraminifera microfossil that commonly used for interpretation of depositional environment is rarely found, whereas freshwater mollusk and vertebrate fossils often found in the sediment rocks of this area.  This condition raises a question, what is the environment of this valley in the past? Data obtained from measured stratigraphic sections along Cisaar river and its tributary rivers in Cibengkung and Cirendang hamlets, Jembarwangi village. There are at least three depositional paleoenvironments which from old to young are: shallow marine, estuarine and fluviatil braided channel depositional paleoenvironment.  Characteristics of the lower, middle and upper of the estuarine environment were found in this Cisaar Valley as the evidences of the oceanic regression processes was happened in the past in this area. 

Effect of rock strength on exhumation and the thermochronologic record: The south-central Colorado example

2021 ◽  
Author(s):  
Sabrina Kainz ◽  
Lon Abbott ◽  
Rebecca Flowers ◽  
James Metcalf
Keyword(s):  
Low Temperature ◽  
Sedimentary Rock ◽  
Rock Strength ◽  
Sedimentary Rocks ◽  
Sedimentary Basins ◽  
Crystalline Basement ◽  
Precambrian Basement ◽  
The West ◽  
South Central ◽  
Sangre De Cristo

<p>Past work has used the Southern Rocky Mountains (SRM) in the U.S. state of Colorado to illustrate the important role that rock strength plays in the histories recorded by the apatite fission track (AFT) and apatite (U-Th)/He (AHe) low-temperature thermochronometers (Flowers & Ehlers, 2018). The SRM were initially raised during the Laramide Orogeny, ca. 70-45 Ma, but consensus exists that the region also experienced a later, post-Laramide exhumation event. Flowers & Ehlers (2018) pointed to the low erosion potential of the Precambrian crystalline basement rocks that crop out in most SRM ranges as a primary reason for the abundance of 55-70 Ma “Laramide” AFT and AHe dates in the region, compared to a paucity of younger dates that would presumably be produced through erosion triggered by the post-Laramide exhumation event. South-central Colorado offers a test of this hypothesis, due to lateral variations in rock erodibility provided by the presence here of both sedimentary and crystalline Laramide ranges and adjacent sedimentary basins. The combination of our ongoing AHe study with previous south-central Colorado AFT and AHe work reveals kilometer-scale post-Laramide (Oligo-Miocene) exhumation has occurred in areas that possess thick sedimentary rock sequences whereas exhumation has been negligible where crystalline basement comprises the land surface. </p><p>South-central Colorado’s Sangre de Cristo Mountains consist of an imbricate stack of thrust sheets composed of Permian sedimentary rock. About 30 km farther east stand the Wet Mountains, another Laramide range – but one composed of Precambrian basement rock. The Raton Basin, a SRM foreland basin filled with 2 km of synorogenic fill underlain by a thick sequence of marine shale, lies south and east of the two ranges. The Wet Mountains thus form a peninsula of strong crystalline rock surrounded by more erodible sedimentary rocks to the west, south, and east. </p><p>Our study and that of Landman (2018) records at least 2 km of erosion in the Raton Basin east and south of the Wet Mountains since 25 Ma. Lindsey et al (1986) obtained 24-15 Ma AFT dates from the Paleozoic sedimentary rocks of the Sangre de Cristo Mountains, demonstrating that kilometer-scale Oligo-Miocene exhumation occurred just west of the Wet Mountains. By contrast, Kelley and Chapin (2004) obtained only pre-Laramide AFT ages between 228-110 Ma for 17 samples of Precambrian basement from the crest of the Wet Mountains. A 32 Ma ash flow tuff unconformably overlies Precambrian basement on Greenhorn Mountain, the Wet Mountains’ highest and southernmost peak. Its presence reinforces the conclusion, based on the AFT dates, that Oligo-Miocene erosion of the Wet Mountain massif has been minimal simultaneous with kilometer-scale exhumation to the west, south, and east. These results illustrate the important role that rock strength plays in determining the dates recorded in low-temperature thermochronologic studies.</p>

3. Sedimentary rocks

2016 ◽  
pp. 29-50
Author(s):  
Jan Zalasiewicz
Keyword(s):  
Sedimentary Rock ◽  
Chemical Weathering ◽  
Sedimentary Rocks ◽  
Chemical Environment ◽  
Combined Effects ◽  
Star System ◽  
The Earth ◽  
Different Types ◽  
Physical And Chemical

The Earth has the greatest abundance and variety of sedimentary strata in our star system, dating back some 3.8 billion years. ‘Sedimentary rocks’ describes the processes that create different types of sedimentary rocks, which form a key guideline in reconstructing Earth’s history. Particles are created by both physical and chemical weathering. These particles are then moved by different modes of transport and sorted by size, which affect the resulting sedimentary rock. Sedimentary layers can remain as soft muds or loose sands for millions of years, but most buried sedimentary layers harden and turn into rock, under the combined effects of increasing heat and pressure, and of changes in chemical environment.

Enigmatic provenance signature of sandstone from the Okwa Group, Botswana

2020 ◽  
Vol 123 (3) ◽  
pp. 331-342
Author(s):  
T. Andersen ◽  
M.A. Elburg ◽  
J. Lehmann
Keyword(s):  
South Africa ◽  
Detrital Zircon ◽  
Sedimentary Rock ◽  
Age Distribution ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Significant Shift ◽  
Zircon Age ◽  
Three Samples ◽  
Isotope Distributions

Abstract Detrital zircon grains from three samples of sandstone from the Tswaane Formation of the Okwa Group of Botswana have been dated by U-Pb and analysed for Hf isotopes by multicollector LA-ICPMS. The detrital zircon age distribution pattern of the detrital zircons is dominated by a mid-Palaeoproterozoic age fraction (2 000 to 2 150 Ma) with minor late Archaean – early Palaeoproterozoic fractions. The 2 000 to 2 150 Ma zircon grains show a range of epsilon Hf from -12 to 0. The observed age and Hf isotope distributions overlap closely with those of sandstones of the Palaeoproterozoic Waterberg Group and Keis Supergroup of South Africa, but are very different from Neoproterozoic deposits in the region, and from the Takatswaane siltstone of the Okwa Group, all of which are dominated by detrital zircon grains younger than 1 950 Ma. The detrital zircon data indicate that the sources of Tswaane Formation sandstones were either Palaeoproterozoic rocks in the basement of the Kaapvaal Craton, or recycled Palaeoproterozoic sedimentary rocks similar to the Waterberg, Elim or Olifantshoek groups of South Africa. This implies a significant shift in provenance regime between the deposition of the Takatswaane and Tswaane formations. However, the detrital zircon data are also compatible with a completely different scenario in which the Tswaane Formation consists of Palaeoproterozoic sedimentary rock in tectonic rather than depositional contact with the other units of the Okwa Group.

Underground Research Laboratories in Japan: What Are the Important Factors for Facilities Design?

2003 ◽  
Author(s):  
T. Sato ◽  
S. Mikake ◽  
M. Sakamaki ◽  
K. Aoki ◽  
S. Yamasaki ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Sedimentary Rock ◽  
Mechanical Stability ◽  
Ventilation System ◽  
Sedimentary Rocks ◽  
Crystalline Rock ◽  
Ventilation Network ◽  
Main Stage ◽  
Middle Stage ◽  
Ventilation Shaft

This paper describes the current status of two Japanese off-site Underground Research Laboratories (URLs) Projects, one for crystalline rock and the other for sedimentary rock. This paper is focused on mechanical stability and ventilation, important factors relevant to the design and construction of deep underground facilities. High-pressure inflow, another important factor, will be included in the URL project for crystalline rock. The site of the URL project for crystalline rock is located in Mizunami, Gifu, in the central part of the main island of Japan. The regional geology consists of the Tertiary and Quaternary sedimentary rocks overlying Cretaceous granitic basement. Surface-based investigations, including geological mapping, a seismic refraction survey and shallow borehole investigations, and site preparation at the MIU (Mizunami Underground Research Laboratory) Project site have started in 2002. Numerical analysis is carried out to understand mechanical stability around the openings. The ventilation system design is based on numerical analysis using a ventilation network model. Grouting against the high-pressure inflow is planned. Conceptual design for the MIU at present is as follows: • Two 1,000 m shafts, a Main Shaft (6.5m φ) and a Ventilation shaft (4.5m φ); • Two experimental levels, the Main Stage at 1,000 m and the Middle Stage, at 500 m depths. The site of the URL project for sedimentary rock is located in Horonobe, Hokkaido, north of the main island of Japan. The geology consists of Tertiary sedimentary rocks. Surface-based investigation phase started in 2001. Numerical analysis is carried out to understand mechanical stability of the openings, and to design support. The numerical analysis using ventilation network model is carried out to design the ventilation system and disaster prevention method. Conceptual design for the Hnb-URL at present is as follows: • Two 500 m shafts and a Ventilation shaft; • Two experimental levels, the Main Stage at 500 m and the Middle Stage at 250 m depths.

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