Research on the Ediacaran and Cambrian of the Anti-Atlas and High Atlas Mountains, Morocco: An historical overview

One of the principal biostratigraphical tools used in the lower Palaeozoic, and especially the Cambrian System, is trilobites. Historically, both polymerids and agnostoids have commonly been included as ‘trilobite’ groups, although currently the question of whether they comprise a monophyletic group or are polyphyletic is unsettled. Beginning in the late 1800s, the base of the Cambrian System was marked by the lowest occurrence of olenelline trilobites. Discovery of a rich pre‐trilobite metazoan record in the mid‐1900s led to significant modification of that concept, but polymerids and especially agnostoids still rank among the leading biostratigraphical and chronostratigraphical guides through much of the Cambrian. Chronostratigraphical sub‐division of the trilobite‐bearing part of the Cambrian System derives largely from biostratigraphical, ecological and evolutionary concepts about agnostoids and polymerids introduced in the 1940s to 1970s by A.H. Westergård, A.R. Palmer and R.A. Robison. Westergård introduced a zonation for Scandinavia that was largely based on agnostoids. Palmer explained the distribution of Cambrian trilobite faunas in terms of restricted and unrestricted access to open oceans. Together, these ideas coalesced in Robison's recognition of separate zonation schemes for restricted‐shelf polymerids, open‐shelf polymerids and open‐shelf (cosmopolitan) agnostoids. Palmer also introduced the concept of biomeres, which placed sharp limits on biostratigraphical intervals recognizable from trilobites. Global correlation in the upper half of the Cambrian today depends to a large extent on the ranges of agnostoids and some polymerids characteristic of open‐shelf to slope areas, ones that facilitate identification of precise intercontinental tie points. Agnostoid and polymerid biostratigraphy is now being integrated with information about coastal onlap and eustatic sea‐level history, geochemical cycling and other data to provide a more complete understanding of the early Palaeozoic biosphere and its complex physico‐chemical context.

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“…; Zhuravleva et al . ; Debrenne & Rozanov ; Rozanov & Sokolov ; Zhuravlev & Repina ; Debrenne , ; Derry et al . ).…”

Section: Cambrian Biostratigraphyunclassified

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Babcock

Shanchi

Ahlberg

2017

LET

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“…Boris' younger brother Georges (1908Georges ( -1986) also made his career as a geologist and spent several decades in Morocco working in leading position for the "Service géologique du Maroc" (Debrenne, 2014). His main emphasize was on the extended outcrops of Proterozoic and Lower Cambrian rocks in southern Morocco (Anti-Atlas belt) and he published several seminal contributions to Precambrian geology (e.g.…”

Section: Boris Choubert (1906-1983)mentioning

confidence: 99%

“…There, two main areas with extensive Precambrian outcrops can be distinguished, the Anti- (see Choubert, 1963 andDebrenne, 2014 for historical accounts). And it was not until the late 1930s and 1940s that the general outlines of Precambrian geology could be unraveled (to a large part due to Boris' brother George).…”

Section: Choubert's Insights Into Precambrian (Mainly African) Regionmentioning

confidence: 99%

A pioneer of Precambrian geology: Boris Choubert’s fit of the continents across the Atlantic (1935) and his insights into the Proterozoic tectonic structure of the West African Craton and adjacent areas

Letsch

2017

Precambrian Research

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Plate tectonics revolutionized the Earth Sciences during the 1960s and led to a fundamentally new view of tectonic processes inside mountain belts. Application of the new theory to pre-Permian and especially Precambrian orogenic belts developed somewhat reluctantly during the 1970s and 1980s. The present article presents and discusses the ideas of Boris Choubert (1906-1983), a French colonial geologist of Russian origin, which he first developed in 1935. He tried to test Wegener's theory of continental displacement (a forerunner of plate tectonics) by applying it to Paleozoic and Precambrian orogenic belts around the Atlantic (a topic altogether neglected by Wegener). To achieve this, he produced a fit of the continents across the Atlantic which is almost identical to the famous 1965 fit of Bullard et al. Starting from this Paleozoic continental configuration, he presented an inter-continental synthesis of Precambrian geology and discussed problems from a wide array of topics, ranging from regional tectonics of the West African Craton, questionable Precambrian fossils, tillites (and cap carbonates) to the supposed origin of detrital diamonds in Gabon and Brazil. He also provided probably the first Precambrian plate reconstruction avant la lettre. After his 1935 paper, Choubert worked for decades in Africa and South America and had opportunity to test and refine his synthesis. His example is a call, addressed to present-day geologists working on Precambrian geology in Africa and other regions, to consult the old colonial literature which contains a wealth of factual information and theoretical inspiration which is still of interest today.

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The Cambrian sedimentology and reservoir properties of the hybrid Abbottabad Formation in the Kotli area, Sub-Himalaya, Pakistan: insights into the Proto-Tethys paleoenvironment

Ali,

Lashari,

Sahito

et al. 2024

Carbonates Evaporites

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Research on the Ediacaran and Cambrian of the Anti-Atlas and High Atlas Mountains, Morocco: An historical overview

Cited by 6 publications

References 10 publications

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

A pioneer of Precambrian geology: Boris Choubert’s fit of the continents across the Atlantic (1935) and his insights into the Proterozoic tectonic structure of the West African Craton and adjacent areas

The Cambrian sedimentology and reservoir properties of the hybrid Abbottabad Formation in the Kotli area, Sub-Himalaya, Pakistan: insights into the Proto-Tethys paleoenvironment

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