Non-marine carbon-isotope stratigraphy of the Triassic-Jurassic transition in the Polish Basin and its relationships to organic carbon preservation, pCO2 and palaeotemperature

New carbon-isotope data obtained from homogenous organic material (separated microfossil wood; δCwood) from the upper Rhaetian and entire Lower Jurassic permit chemostratigraphic correlation of these marginal/non-marine deposits with the biostratigraphically well-constrained Llanbedr (Mochras Farm) core in N Wales and other marine profiles, supported by sequence stratigraphic correlation and biostratigraphical markers. Statistically significant (Rs = 0.61) positive exponential correlation between δCwood values and continental TOC (TOCcont) concentrations occurs and can be defined empirically by equation. Changes of δCwood observed in C3 plants depends on δ CO2 of atmosphere and can be modulated by other factors such as pCO2 causing fractionation (enrichment in C) of C isotopes in source C3 plants and, to lesser extent, by soil moisture content. Floral remains occurring in the relatively stable palaeolatitude and climatic zone of the Polish Basin in the time interval studied lend no support for significant precipitation impact on the δC fractionation, although enhanced precipitation could have had a limited impact during the Toarcian Oceanic Anoxic Event (T-OAE). We argue that the observed relation between δCwood values and TOCcont reflects the global carbon cycle forcing. Such correlations may develop because fluxes of of C-enriched methane, mobilized from near-surface carbon sources, lead to global warming, decreased δCwood and enhanced (usually fungally-mediated) decomposition of the terrestrial carbon pool, while subsequent massive burial of organic carbon results in higher δC values in all carbon cycle reservoirs, and the attendant drawdown of atmospheric CO2 leads to global cooling and promotes sequestration of soil organic matter. In turn, this relation can be used as an indirect indicator of atmospheric temperature trends, although organic carbon isotope records are potentially subject to many different influences. Based on the δCwood /TOCcont relationship, an approximate qualitative estimation of general trends in air temperature is suggested for c. 40N paleolatitude and the warm temperate climatic zone. The observed hypothetical trends in temperature are generally in Jo ur na l P re -p ro of Journal Pre-proof

A new and unique geological archive (2050.6 m through the Norian -Rhaetian-Lower Jurassic strata) comes from the Kaszewy 1 borehole (Fig. 1), drilled in central Poland (52˚ 12΄ 00.06˝ N; 19˚ 29΄ 35.38˝ E) by PGE (Polish Energy Group) in order to characterize the potential for carbon capture and storage (CCS) in that area. The entire core has been thoroughly logged and sampled. Samples for geochemical analyses have been taken from similar lithologies (mudstones) in order to avoid lithological bias. The length and continuity of the Kaszewy core (98 % core recovery) is essential in studying continental or marginal-marine deposits by sedimentological methods and allowing application of isotope chemostratigraphy of these facies, supported by sequence stratigraphy and some biostratigraphical markers (Fig. 2). For comparison to Kaszewy we use the new compilation from the biostratigraphically constrained Mochras core (Storm et al, 2020) which covers the entire Early Jurassic, reproducing large-amplitude δ 13 C TOC excursions (>3 ‰) at the Sinemurian-Pliensbachian transition and in the lower Toarcian serpentinum Zone, as well as several previously identified medium-amplitude (~0.5-3 ‰) shifts in the Hettangian to Pliensbachian. In addition, δ 13 C wood (Storm et al, 2020) and δ 13 C carb (Katz et al 2005) data was also obtained (Fig. 2).

Carbon isotopes
Phytoclast samples for analysis were manually picked from HF palynomacerals and subsequently dried, weighed and sealed in tin capsules. Phytoclast samples were run at two laboratories, depending on their mass (Supplementary data 1). At the Research Laboratory for Archaeology and History of Art (RLAHA), University of Oxford, UK, larger samples were run on a Sercon Europa EA-GSL sample converter connected to a Sercon 20-22 stable isotope gas-ratio mass spectrometer running in continuous flow mode with a helium carrier gas with a flow rate of 70 ml per min. Carbon isotope ratios were measured against an internal alanine standard (δ 13 C alanine = -26.9 ± 0.2‰ V-PDB) using a single point calibration. The in-house RLAHA alanine standard is checked weekly against USGS40, USGS41 and IAEA-CH6 international reference materials. At the at the British Geological Survey, Nottingham, UK, smaller samples were analysed by combustion in a Costech Elemental Analyser (EA) on-line to a VG TripleTrap and Optima dual-inlet mass spectrometer, with δ 13 C org values reported relative to V-PDB following a within-run laboratory standard calibration, with NBS-18, NBS-19 and NBS-22. Replicate analysis of well-mixed samples show a reproducibility of ± <0.1‰ (1 SD).

Total Organic Carbon, Rock Eval 6 pyrolysis
Total Organic Carbon (TOC) analyses of 300 samples were performed using the chromatographic, coulometric method (procedure PB -23) using an automated LECO analyser (Supplementary data 1).
A total of 52 naturally carbonate-free mudstone samples (mostly those representing mixed environments -in order to evaluate which ones contain more marine kerogen) were analyzed in the J o u r n a l P r e -p r o o f Rock Eval pyrolysis apparatus -model 6 Turbo (Vinci Technologies), in the laboratory of the Polish Geological Institute (Supplementary data 2). Crushed bulk rock material was thermally decomposed in a helium or nitrogen atmosphere. Every sample was heated to 650°C. The amount of free hydrocarbon (S1) thermally liberated from a rock sample at 300°C is measured using a Flame Ionization Detector (FID). Volatile components released during pyrolysis are separated into two streams. One of them passes through the FID and is registered as peak S2. Another volatile component released during pyrolysis, i.e., carbon dioxide generated from kerogen, is recorded by a thermal conductivity detector as the S3 peak. Repeat analyses of the parameters S1, S2, S3 and TOC agree within ±0.05. The Oxygen Index (OI, in mg CO2/g TOC) is calculated according to the formula (S3*100)/TOC. Hydrogen index (HI) = S2 (mg/g)/TOCx100. Only mudstone was sampled, therefore some parts of profile are sampled more sparsely due to the high sandstone content and sample spacing is heterogeneous. Coals and coaly mudstones were avoided as non-representative. Parts containing marine kerogen were sampled more sparsely. Only samples paired with δ 13 C wood data and of clearly continental origin (dominating kerogen type III and IV, about 80% of all samples) were used for δ 13 wood , TOC cont and temperature interpretation ( Fig. 2; Supplementary data 1, 2).

Stomatal index (SI)
Fifty-one specimens containing fossil plant remains from the Kaszewy core interval 1936.5-1296 m were studied. Only few levels contained well preserved remains with preserved cuticle, belonging mostly to genera Baiera Braun emend Florin and Czekanowskia Herr, on which the SI counting has been performed. Their determination was possible on a genus level only, but that is not a limitation for stomatal index study. Baiera and Czekanowskia are ginkgophytes, which means that all studied remains have the same nearest living equivalent species (NLEs), making ginkgophytes especially suitable for SI calculation (Beerling et al 1998;Xie et al 2006 J o u r n a l P r e -p r o o f

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Standardization was applied after Berner and Kathavala (2001) and SI for the extant Ginkgo biloba was used according to Beerling and Royer (2002a), as 9.1 at 350 ppm. Based on this relationship, palaeoatmospheric CO 2 pressure (pCO 2 ) was estimated, using stomatal parameters of fossil plantsstomatal density (SD) and stomatal index (SI) in relation with parameters of their NLEs, defined as the stomatal ratio (SR) (Beerling and Royer 2002a;Beerling and Royer 2002b;Royer et al 2001) . Plant reaction appears in leaf structure, especially in stomatal density, which is closely associated with fluctuations of atmospheric pCO 2 and displays an inverse correlation to pCO 2 (Woodward 1987;Beerling 1999;Pole and Kürschner 1999;Mosbrugger 1999;Royer et al 2001;Haworth and Raschi 2014). SI may be influenced by many factors that affect plants during their life, but, as has been discussed by many authors Chen et al 2001;Erdei et al 2012), the estimated pCO 2 values are not invalidated (except very young, undeveloped leaves which are not appropriate to SI calculation).

Stratigraphy
The sediments studied yielded very few animal body fossils. Of note is a single find of ammonite Tragophylloceras cf. loscombi (Sowerby) in a 1.5 m thick grey shale at a depth of 1281.5 m (Pieokowski 2015). The stratigraphical range of this species is rather wide, ranging from upper lower Pliensbachian to lower upper Pliensbachian (from the upper part of the ibex Zone/ centaurus Subzone to the upper part of the subnodosus Subzone of the margaritatus Zone (Howarth and Donovan 1964). Other methods, such as sequence stratigraphy (Pieokowski 2004; and carbon isotope chemostratigraphy point to the uppermost part of this ammonite's range, i.e.
subnodosus Subzone. Next, some palynomorphs provide constraints on the Triassic -Jurassic boundary. Of note are common appearances of Ricciisporites tuberculatus Lundblad, a pollen assigned to an enigmatic gymnosperm and known for its common occurrences in the Rhaetian (Lindström et al 2017), with a last occurrence of 1890.2 m. Slightly above (1879 m) there is also the last occurrence of Brachysaccus neomundanus (Leschik) Madler, which was previously described from Rhaetian deposits in NW Poland (Pieokowski et al 2012

J o u r n a l P r e -p r o o f
For chemostratigraphic correlation of the Lower Jurassic succession, the best prospect lies in carbon isotope values obtained from similar material (δ 13 C organic, δ 13 C wood ) because, with the exception of purely pelagic carbonate palaeoenvironments, the carbon-isotope signature of any carbonate present is vulnerable to diagenesis, which is also borne out in the δ 13 C carb curve from Mochras presented by Katz et al (2005). However, comparison between the δ 13 C org, δ 13 C wood and δ 13 C carb curves can still be useful in indicating the most reliable primary CIEs; therefore selected δ 13 C carb curves can also be used, particularly if δ 13 C org curves are not available (Fig. 3). Chemostratigraphical correlation of Mochras and Kaszewy is uniquely valuable, as these two profiles are the most expanded,

Total organic carbon (TOC), kerogen analyses
In the Rhaetian strata, TOC is usually below 1%, except for some darker mudstones interpreted to have been deposited in local ponds and lakes, where TOC content can reach 4% and more. The lowermost part of the Rhaetian strata is represented by red beds yielding very few or no palynomacerals (Supplementary data 1) and these strata are excluded from further considerations concerning TOC and δ 13 C wood as non-representative. In the Hettangian section TOC is in places abundant ( Fig. 2), but most of these intervals contain marine kerogen (Supplementary data 2) occurring mostly in strata coeval with major transgressions of the planorbis and liasicus zones (Pieokowski 2004;. In the upper Sinemurian -lower Pliensbachian section the studied samples usually contain more than 1% (1.14% in average). Moreover, a few beds have TOC up to 3-5 %, and the sample from the lowest part of Pliensbachian (depth of 1462.3 m) contains organic carbon as high as 15.3%. These samples contain marine kerogen associated with the jamesoni-ibex transgression and maximum flooding surface (Pieokowski 2004;. In the upper Pliensbachian -Toarcian section TOC is usually in the range of 0 to 3% (1.0% on average).
In contrast, most of the lower Toarcian is characterized by a low content of TOC (usually below 0.5%).
In order to check the character of the kerogen, 52 mudstone samples from selected sections (based on sedimentological studies) were screened using RockEval 6 pyrolysis and interpreted using the Van Krevelen plot (Supplementary data 2). Kerogen was classified in classical types II, III and IV (type I has not been found), ranged in the order of H/C ratio obtained from the RockEval6 analyses. Type II originated in a shallow marine environment with phytoplanktonic input as the primary source. Type III and IV are found in deltaic/fluvial and coastal settings and derive from higher plant debris, commonly highly reworked and often degraded by fungi (Fig. 6

Carbon isotope -total organic carbon ratio
The cross-plot of the δ 13 C wood to TOC cont ratio (224 Rhaetian  Australian (900 ppm based on araucarialean conifers) material (Steinthorsdottir and Vajda 2015)see Fig. 7 and discussion by Barbacka (2011). Generally, the differences in SI and pCO 2 calculations are not outstanding: pCO 2 values oscillate within certain range and average values are given.
Nevertheless, some inaccuracies are possible, for example pCO 2 can be also influenced by the  (2001). We observe that Czekanowskia and Baiera stomatal density (sensitive to pCO 2 and consequently temperature differences) is generally compatible with δ 13 C wood , while these genera are not themselves specifically related to a strict range of temperature. Their deciduous character is connected with seasonal temperature and precipitation variations (Fig. 7). Both genera commonly occur together among dominant elements of Siberian-Canadian provinces and are known as mesotemperate plants, characteristic of flood plain/delta peatforming assemblages (Rees et al 2000). The interpretation of the relationship between δ 13 C wood and TOC cont must rely on some baseline assumptions. The carbon cycle includes many simultaneous processes with different time scales, involving very complex processes of carbon mass and isotopic fluxes to and out of the oceanatmosphere system. Concerning the carbon cycle, in particular the fluxes into the atmospheric system, we focus here on processes registered in plant matter (Gröcke 2002). Experimental data from plant growth chambers obtained by Schubert and Jahren (2012), further developed by Cui and Schubert (2016) allowed formulation of a simple model (identified as the C3 proxy) in which plant carbon-isotope composition depends on changes in only two atmospheric variables, i.e. source isotopic composition of carbon dioxide (δ 13 CO 2 ) and the pCO 2 . However, for δ 13 C to be used as an accurate and precise method to reconstruct pCO 2 the major requirement is to demonstrate that changes in CO 2 are the main driver of changes in δ 13 C. It should be emphasized that only those experiments which are based on C3 plants can be taken in account for the current study, as C4 plants . Additionally, increasing pCO 2 causes δ 13 C negative fractionation by C3 plants and both caused the negative isotopic signal registered in fossil plants (Hare et al 2018). Similarly, enhanced decomposition of continental carbon pool caused by rising temperature has a short-term, strong feedback effect (Pieokowski et al 2016). The rising pCO 2 was a major factor in raising temperature, and temperature growth led to depletion of TOC cont .
On the other hand, increasing pCO 2 , climate warming and enhanced hydrological cycle (causing enhanced delivery of nutrients to the oceans) lead to increased ocean productivity and increased rate of burial of organic carbon, resulting in drawdown and fall in atmospheric pCO 2 , and positive excursions in both organic and inorganic carbon (Kump and Arthur 1999). The drawdown of atmospheric CO 2 led to global cooling and higher accumulation of TOC cont .
Significant, moderate or strong (Evans 1996) (Figs. 2, 5, 7). If it is assumed that the temperature is the main factor of TOC cont reduction, then we can link the observed relationship between δ 13 C wood and TOC cont to the temperature warming-cooling trends, associated with global carbon cycle. An important point is that J o u r n a l P r e -p r o o f this correlation does not demonstrate δ 13 C wood -temperature direct causation. In this case, the δ 13 C wood , temperature and TOC cont would be responding to another forcing (CO 2 fluxes and C org burial, i.e. carbon cycle -cf. Gröcke et al 1999). Additionally, possible influence of sedimentary and diagenetic factors, reflected also as palynofacies inversions (Pieokowski and Waksmundzka 2009) could alter the TOC cont content. On the other hand, extremely enhanced hydrological cycle at the peaks of T-OAE could have had some impact on the observed δ 13 C wood -TOC cont relation, in that organic matter would have been rapidly removed and delivered to the receiving basin before the decomposition processes had fully taken effect. This could be responsible in slightly reversed δ 13 C wood -TOC cont trend observed in four Toarcian samples with most negative δ 13 C wood values (Fig. 5).
Weaker correlation in the entirely continental Rhaetian section can be explained by much stronger impact of local environmental factors, influencing strongly differentiated TOC cont sequestration that is facies specific in space and time, for example fluvial plain/lacustrine shifts of environments. In (2011) - Fig. 7. The general pCO 2 /temperature trends inferred from SI correspond with the δ 13 C wood changes (Fig. 7).

Variables influencing δ 13 C wood and TOC cont -discussion
The δ 13 C wood of plant matter in the geological record would be generally dependent on the δ 13 C of the palaeoatmosphere (Hasegawa 1997;Hesselbo and Pieokowski 2011;Schubert and  increasing pCO 2 would amplify the observed overall δ 13 wood values, and increased pCO 2 would result in temperature rise and subsequent reduction of TOC cont . Interestingly, there is also a direct positive feedback between elevated atmospheric CO 2 concentrations and soil organic matter decomposition (Wolf et al 2007). Fractionation by different plant organs related to different plant taxa or seasonal precipitation changes should also be considered. However, any sample of wood material analysed herein would also contain averaged isotopic signals spanning tens, hundreds or thousands of yearsaveraging out specific fractionation factor of the originating plant taxon, or the part of the plant from where the wood comes. This conclusion is supported by the common observation of parallel stratigraphic trends in δ 13 C wood values and δ 13 C of bulk marine organic matter (e.g. example of Toarcian of Lusitanian Basin (Hesselbo et al. 2007, Fantasia et al. 2019. It should be also noted that only the Coniferales and Ginkgophyta produced significant amounts of secondary xylem and most of our wood likely came from conifer trees (Morgans 1999;Philippe et al 2006;Pieokowski et al 2016).
The amount of TOC cont could be also controlled by the rates of production, not only degradation.
However, if production rate were the significant controlling factor, then we should expect maximum concentrations of TOC cont during the periods characterized by highest humidity, pCO 2 and, consequently, productivity (e.g. T-OAE - Pieokowski et al. 2016). However, the situation is exactly opposite and TOC cont is very low during T-OAE, most likely due to a rapid decomposition (Figs. 2, 6).
Another factor which could influence TOC concentration is the sedimentation rate -the higher it is, the lower TOC concentration should be. However, the highest overall sedimentation rate occurred in Hettangian, where the average TOC cont content is highest (Fig. 2). Constraints on the late Rhaetian and Early Jurassic environment in Poland based on reconstruction of the hydrological cycle, standing vegetation and clay mineral analysis (Hesselbo and Pieokowski 2011;Braoski 2009Braoski , 2012 J o u r n a l P r e -p r o o f et al 2012, 2014, 2016) does not indicate the presence of dry or semi-dry habitats, except for short periods in the late Rhaetian (these samples were excluded from our δ 13 C wood -TOC cont considerations).
Macrophyte remains in Kaszewy (Fig. 7) and hitherto analysed palynomorphs in the late Rhaetian and  2) shows lack or a minimum content of bryophyte and lycophyte spores through the Toarcian, in particular during the T-OAE. However, data from the Polish basin, located approximately at the same paleolatitude, show prominent and continuous share of spores and megaspores produced by extremely hydrophilic lycophyte (e.g. quill worts) through the T-OAE (Marcinkiewicz 1962(Marcinkiewicz , 1971Pieokowski and Waksmundzka 2009;Hesselbo and Pieokowski 2011;Pieokowski et al 2016). Plant chamber experiments have also revealed relationships between carbon isotope discrimination and changing pO 2 (Porter et al 2017), but this variable in the geological record is interpreted from reconstructions which vary widely, particularly for the Mesozoic and early Cenozoic eras (Glasspool and Scott 2010). In respect to the geological time interval studied herein, these low-J o u r n a l P r e -p r o o f resolution models are often controversial, although they confirm a general rule that high rates of organic carbon burial results in subsequent oxygen production (Krause et al 2018).
The described herein δ 13 C wood /TOC cont relationship is surprising. However, if the correlation is so significant, it follows that there is a natural reason for it. There is also a relationship between terrestrial TOC and temperature from actualistic experimental work. As we wrote above, decomposition of soil labile carbon is highly sensitive to temperature variation and elevated pCO 2 resulting in higher temperature could be conducive for enhanced soil organic matter decomposition (Fang et al 2005;Feng et al 2008;Pieokowski et al 2016;López-Mondéjar 2018). The continental kerogen studied herein had likely been oxidized on land or in rivers and before delivery to the receiving basin -remineralization of TOC cont in a marginal-marine basin was possible, but among different continental types of organic matter, the wood and charcoal was least affected by degradation in the basin (Pieokowski and Waksmundzka 2009). Even the most critical approaches (Davidson and Janssens 2006) admit that despite controversies, the observational data are converging to demonstrate that irrespective of labile or recalcitrant character, the soil carbon pool decomposes with apparent detectable temperature sensitivity (Fang et al 2005;Feng et al 2008). Wood is known to react more to higher temperature changes (kinetic theory), which can explain why the population of samples with more diversified δ 13 C wood and TOC cont values (e.g. Toarcian) shows relatively higher coefficiency in δ 13 C wood / TOC cont function (Fig. 5).
Considering the above arguments, it should be noted that some emerging reports from Lower Jurassic marine sediments (Hesselbo et al 2020b;Ullmann et al 2020) demonstrate a lack of correlation between δ 13 C org and δ 18 O (reflecting in general, although still debatably, sea-water temperature) in some sections, for example the lower Sinemurian in UK or the Toarcian in Iberia.
However, Schöllhorn et al (2020) show good convergence between these two variables in Sinemurian of Dorset (UK), while there are divergences in the lower Pliensbachian. Of note is also the fact that Hesselbo et al. (2020a,b) (Suan et al. 2008;Fantasia et al. 2019). Nevertheless, existing δ 13 C and δ 18 O divergences tend to cast some doubts, at least on universality of δ 13 C org and δ 18 O/temperature relations because one should expect even stronger relationship between these parameters in marine sediments than there is between δ 13 C wood and marine temperature, as the J o u r n a l P r e -p r o o f relationship is more direct. However, there are some inherent uncertainties regarding δ 13 C and δ 18 O results from marine deposits and their interpretation. It is now well established that bulk organic Cisotope records need to be regarded with caution due to the mixing effects of different types of carbon, each with their own δ 13 C signature Suan et al. 2015;Schöllhorn et al. 2020). In Kaszewy these problems are avoided, because the δ 13 C wood values comes from homogenous material. The other question is the possible influence of oceanographic processes, acting (at least partly) independently from global atmospheric pCO 2 and temperature changes.
Opening of the Hispanic corridor in Sinemurian and its widening in Pliensbachian (Porter et al. 2013) impacted oceanic circulation, marine faunal exchange pattern and, very probably, also isotopic and temperature pattern in the Jurassic seaways of the European area.
The current paper supports and extends similar results obtained from the late Pliensbachianearly Toarcian deposits of the Polish basin (Pieokowski et al. 2016) and this is a first attempt to infer a continuous record of air temperature trends through such a long period of geological time.
Independently obtained trends of interpreted palaeotemperatures are juxtaposed with data from stomatal index which are thought to represent changes in pCO 2 . It seems that the proposed relationship works as a temperature signal only for a warm/winter-wet climatic zone. The δ 13 C wood / TOC cont trend observed in the semi-arid climate belt seems to be different, at least during the Late Pliensbachian-early Toarcian interval in the Southern Tethyan and Iberian margin (Rodriguez et al 2019). It is possible that during the T-OAE the Southern Tethyan and Iberian margin was influenced by the adjacent tropical climatic zone, which caused the observed differences. Of note is also modeling of major carbon cycle perturbations around the Triassic-Jurassic boundary, showing coincidence between δ 13 C and pCO 2 changes (Heimdal et al. 2020).

1.
There is an observed highly significant relationship between δ 13 C wood and TOC cont in the Rhaetian/Lower Jurassic from Kaszewy that can be defined by an equation. The premise is that in mid-latitudes, a controlling factor on the relation between δ 13 C wood and preservation of continental total organic carbon (TOC cont ) is the efficiency of terrestrial biodegradation which is pCO 2 and temperature dependent, although there are several factors that control both  13 C wood and TOC cont .

2.
The δ 13 CO 2 of the Rhaetian and Early Jurassic was largely controlled by δ 13 C-depleted fluxes in and out of the ocean-atmosphere system. Likely, there is are non-causal correlations between δ 13 C wood , TOC cont and temperature trends. Such correlations may develop because massive fluxes into the ocean-atmosphere system and subsequent burial of 13 C-depleted organic carbon (flux out of the J o u r n a l P r e -p r o o f ocean-atmosphere system), at a global scale results in global warming and cooling episodes, registered in the continental carbon pool as δ 13 C wood and TOC cont fluctuations.

3.
The relationship between δ 13 C wood and TOC cont can hypothetically be be useful, even if noncausal, for ~25 Myr long latest Rhaetian and Early Jurassic air temperature interpretation at c. 40 o N paleolatitude. However, its utility depends on how strong the carbon cycle signal is, and how many other influences have operated on the system.

4.
Independently obtained trends of interpreted palaeotemperatures were juxtaposed with data from stomatal index which are thought to represent changes in pCO 2 , and results obtained from stomatal index calculations are compatible with the interpreted temperature trends.

5.
In our material, deposits of coastal/deltaic environments are most suitable for studying the relationship between carbon-isotopes, continental TOC, and temperature, because these facies contain more representative, averaged material delivered from a large catchment areas -in contrast to alluvial plains where TOC is dependent on a more localized fluvial setting.

6.
Unique, expanded and continuous cores from Kaszewy and Mochras allowed reliable δ 13 C chemostratigraphic correlation of marine and marginal/non-marine Lower Jurassic deposits.

7.
While this study suggests an overall implication for Earth system studies and offers potentially independent means (registered in the continental carbon pool) to estimate latest Triassic to Early Jurassic atmospheric temperatures, the relationship between TOC cont , δ 13 C wood and temperature should be further tested and treated as still hypothetical because in general organic carbon isotope records are potentially subject to many different influences.  Considering the above reasons, δ 13 C wood correlation and correlations with other profiles (Fig. 3), the first option was adopted as more likely, despite more similar general isotope trends when adopting the second option.    stomatal index and macrofloral data and tentatively on the δ 13 C wood / TOC cont plot (Fig. 5) . Macroflora represents three general assemblages: Czekanowskia-Pseudotorellia (relatively drier-cooler conditions), Baiera-Ginkgoites-Sphenobaiera (relatively warmer and more humid) and Neocalamites-Schizoneura (humid). Climatic trends are indicated with their inferred stratigraphic age.