The variation of the Earth's surface landscape through geological time results from interplay between intrinsic and extrinsic forces. Both are controlled by first-order tectonic plate geodynamics under varying climatic conditions. The latter is significant for understanding the evolution of Earth's surface processes in the geological record and predicting future climate change scenarios. The balance between intrinsic and extrinsic forces triggers the vertical uplift of orogens and connected subsiding basins and the denudation of the built orogen's relief, respectively. Thus, tracking the Earth's past climate change and its interaction with the earth's sub-systems (i.e., geosphere, hydrosphere, atmosphere, and biosphere) from the source to the sink. This should be of paramount interest to better constrain the evolution of Earth's surface processes and their complex interactions with earth's sub-systems through geological time to expect future climate change scenarios (see Tierney et al., 2020).
Nowadays, the scientific community shows worldwide interest in climate change and its impact on the geological record, which may better constrain our knowledge on the topic. Even if the early alpine history during Jurassic of the prominent landform of plate assemblages is well known, little data regarding their climate and related climate-process systems are available. Thus, further research is necessary to enhance our knowledge of the Jurassic climate, mainly in areas belonging to the northern Gondwana boundary (see Price and Sellwood, 1997; Price and Page, 2008; Riccardi, 1991; Podlaha et al., 1998; Price and Gröcke, 2002; Gröcke et al., 2003; Fürsich et al., 2005; Lécuyer and Bucher, 2006; Jenkyns et al., 2012; Alberti et al., 2012a, b, 2013, 2017; 2019).
According to some authors (e.g., Hallam, 1993; Sellwood and Valdes, 2006, 2008; Holz, 2015; Li and al., 2022) the Jurassic climate has been considered warm. While others(e.g.Dromart et al.,2003; Royer 2006; Bodin et al., 2017, Bodin et al.,2020; Krencker et al., 2019; and Scotese et al., 2021)reported the occurrence of “cool modes” middle Jurassic climate, qualified as “Callovian Ice Age” (e.g.Dromart et al., (2003). The climate change during the Jurassic period is of paramount interest for highlighting climate-process systems exclusively in the north boundary of the Gondwana realm which was a wide north western Gondwana passive margin of the Tethysian realm.
The Jurassic is a classical greenhouse period marked by high atmospheric CO2 concentration (Takashima et al., 2006), as an appropriate modern-day analogue to better constrain climate changes through the Earth's history (Dera et al., 2011). The goal of the present work is to contribute to the knowledge of the Earth's climate change through geological time to better understand how and why it has changed and to endeavor to predict future climate change (Tierney et al., 2020, Scotese, 2021; Skea et al. 2022; Burgener et al.2023).
Indeed the middle Jurassic was a critical geological epoch characterized by global geological events in the Earth's history (Dera et al., 2011), such as first-order plate tectonics triggered the Pangea and Gondwana final breakup (e.g., Bartolini and Larson, 2001; Martini and Ortega- Gutierrez, 2018) and subsequent continental rifting, leading to the opening of new seaways and the onset of seafloor spreading in the central Atlantic, the western Tethys and large-scale oceanic corridors (e.g., Labails et al., 2010; Dera et al., 2015; Scotese et al., 2021).These events have occurred coevally with climate fluctuations started from late early Jurassic marked by a shift from late Pliensbachian “cool event” (Korte and Hesselbo, 2011; Korte et al., 2015) to a warm Toarcian Oceanic Anoxic Event (TOAE) (Jenkyns, 1988; Bailey et al., 2003; Rosales et al., 2004; Korte et al., 2015), and back to a cooling event since the early Aalenian (Korte et al., 2015).
An important debate has been raised exclusively for the Jurassic climate during the critical middle-late Jurassic transitional period considered by some authors (Norris and Hallam ,1995; Jacquin et al.,1998; Hallam ,2001; Wierzbowski et al. ,2009) as a global warming event, with a significant sea-level rise (Wierzbowski et al., 2009; Wierzbowski and Rogov, 2011), driven by enhanced volcanic activity, tectonic uplift of oceanic ridges, and the reorganization of the seafloor oceanic spreading which increased greenhouse gases considered as a potential source of the atmospheric CO2 concentration raise during thisperiod (Wierzbowski et al., 2009, 2012), and therefore responsible for the climate warming (Sellwood and Valdes, 2008; Holz et al., 2015).On the other hand, Dromart et al. (2003); Nunn (2009); Price and Rogov (2009); and Donnadieu et al. (2011) supported an opposite hypothesis suggesting that the middle-late Jurassic transitional period (160 Ma) may correspond to a severe “cooling event” simultaneous with an abrupt global-scale fall of sea level suggestive of continental ice formation at this time and due to a global cooling (Scotese et al., 2021).
The main knowledge accumulated on the earth is mainly reported from marine records (e.g., Alberti et al., 2020). Here we are more interested in the middle Jurassic climate of mid-latitude provinces where the seawater temperatures were cool (about 10°C) and which occurred coevally with the northern Sea Dome in the southern part of the Viking Corridor and which was responsible for a large-scale volcanic activity impacting the oceanic circulation by preventing the equatorial warm oceanic current to reach the Northern Polar region (Korte et al., 2015).
Forecasting the earth's surface processes under Jurassic climate change in the northern African passive margin during the Jurassic has been undertaken by combining different geochemical (Major, trace, and rare earth elements) proxies and of clay mineralogy to better assess weathering intensity, chemical variations and sediment supply from continental sources to neighboring oceanic sinks under Jurassic paleoclimatic conditions impacting the sediment and organic matter redistribution in the oceanic sink by the near-surface hydrological source to sink processes.
To better constrain the paleoclimate change within the western edge of the northern Gondwana passive margin and related Intrarif-Mesorif-Prerif sub-domains which could be considered as "paleo-Critical Zone" sensu Nordt et al., (2012) and Ashley et al.(2020), characterized by a complex interplay between the Earth’s subsystems (Hyland and Sheldon, 2016)during the Jurassic time and where some scientific issues are not yet resolved. Thus the main objective of this work is to: i) provide new constraints on paleoclimate, and related earth processes, ii) evaluate chemical weathering and fluxes transfer from source to sink under climate change, iii) assess paleo-redox conditions and related depositional palaeoenvironments and paleoproductivity, iv) better understand the floral landscape and related paleogeography ,and to v) integrate the obtained data within a regional and global framework.