Modèle de sédimentation au passage Cénomanien/Turonien pour la formation Bahloul en Tunisie

 Mohamed Soua a,*, Nicolas Tribovillard b

Soua & Tribovillard, 2007.pdf

 

a. Entreprise tunisienne d’activités pétrolières, ETAP–CRDP, 4, rue des Entrepreneurs, La Charguia II, 2035, Tunisie

b. UMR 8110 et FR1818, Sciences de la Terre, université Lille-1, bâtiment SN5, 59655 Villeneuve-d’Ascq cedex, France

  

Résumé

Plusieurs études multidisciplinaires ont été effectuées sur les couches riches en matière organique (MO) de la formation Bahloul. Nos études de terrain et les synthèses géologiques, géochimiques, isotopiques et minéralogiques disponibles ont permis d’apporter des précisions nouvelles d’ordre paléogéographique et paléocéanographique. Ces données ont contribué à l’élaboration d’un modèle de dépôt sous une zone à minimum d’oxygène (ZMO) dans des bassins marins profonds et subsidents de type bathyal, où se sont accumulées et préservées d’importantes quantités de MO (jusqu’à 18,7 % de COT). Le présent modèle a permis la corrélation de la formation Bahloul à d’autres coupes de référence à l’échelle globale, ce qui permet de mettre en évidence que le  d13 C mesuré sur MO serait un meilleur outil de corrélation que le  d13 C mesuré sur carbonates pour reconnaître la limite Cénomanien/Turonien.

Abstract

Several multidisciplinary studies were undertaken on the Cenomanian/Turonian organic-rich Bahloul Formation. These studies, as well as our new data, led to some new palaeogeographic and palaeoceanographic interpretations. Based on these data, a depositional model was elaborated, pointing out that at the C/T transition an oxygen minimum zone (OMZ) impinged onto the South Tethyan margin through the Tunisian intrashelf basins formed during Early Cretaceous. This model allows correlating the Bahloul Fm. to other OAE-2 formations throughout the world. It also indicates that the  d13Corganic carbon seems to be a better correlation tool than d13Ccarbonate

LES RÉPONSES BIOTIQUES DES RADIOLAIRES À L’ÉVÉNEMENT ANOXIQUE DU CÉNOMANIEN SUPÉRIEUR DANS LA MARGE SUD TÉTHYSIENNE (TUNISIE)

 

Mohamed Soua 1; Dalila Zaghbib-Turki 2; Luis O’Dogherty 3

Soua et al., 2006.pdf

1.Entreprise Tunisienne d'Activités Pétrolières, Tunisie

2. Faculté des Sciences de Tunis, Tunisie

3. Université de Cadiz, Espagne

 

 

RÉSUMÉ

Pour la première fois en Tunisie, la Formation Bahloul d’âge Cénomanien supérieur – Turonien inférieur est étudiée pour son contenu en radiolaires dans la région de Bargou. Cette Formation présente à la fois un faciès laminé riche en matière organique et en silice. La microfaune observée est d’une diversité faible, avec un maximum de dix huit espèces par échantillon. Vingt-cinq espèces ont été déterminées au total. Les assemblages sont représentés par des nassellaires à test sphérique cryptothoracique / cryptocéphalique et à test multisegmenté, durant tout le Cénomanien supérieur, notamment les représentants des genres Stichomitra, Pseudodictyomitra et Rhopalosyringium. Au Turonien inférieur, la dominance des spumellaires est observée. La préservation des radiolaires (ou indice de préservation PI) déterminée dans cette étude est relativement faible, ce qui suggère une influence d’altérations diagénétiques. En se basant sur la courbe de d 13Corg, cet intervalle correspondant à l’événement anoxique du Cénomanien-Turonien (EAO-2) a été identifié dans la série étudiée. Deux zones de radiolaires ont été reconnues pour cet intervalle. La rareté d’échantillons ayant livré des radiolaires au sein de l’EAO-2 indiquerait une productivité primaire élevée avec des répercussions de conditions chimiques défavorables pour la prolifération de ce groupe durant tout l’intervalle.

Mots clés : radiolaires ; Cénomanien-Turonien ; Foraminifères planctoniques ; Formation Bahloul ; EAO-2.

ABSTRACT

The late Cenomanian-early Turonian Bahloul Formation is investigated for the first time in Tunisia for its radiolarian content. It includes a characteristic interval of organic-rich black laminated and siliceous shales. These deposits yielded twenty five radiolarian species. These assemblages are composed of spherical cryptothoracic / cryptocephalic and multisegmented nassellarians during the whole late Cenomanian interval, represented mainly by Stichomitra and Pseudodictyomitra species. Preservation Index (PI) identified in this study is relatively moderate to poor reflecting some diagenetic alteration influence. Based on the d 13Corg curve, the OAE-2 was recognized inside the Bahloul Formation. Two radiolarian zones are identified in this paper. The scarcity of radiolarian samples along the OAE-2 may indicate a high primary productivity with unfavourable chemical conditions influx for the thriving of this group.

Keywords: radiolarians; Cenomanian-Turonian; planktonic foraminifera; Bahloul Formation; OAE-2

 

HIGH-RESOLUTION BIOTIC RECORDS OF THE LATEST CENOMANIAN - EARLY TURONIAN BAHLOUL FORMATION (OAE-2,) IN CENTRAL TUNISIA

 Mohamed SOUA

1,2

Soua, 2004.pdf

 

1. Département de Géologie Faculté des Sciences de Tunis, 2092 Campus Universitaire El Manar, Tunisie

2. UMR 8110 CNRS-USTL Processus et Bilans des Domaines Sédimentaires, Batiment SN5 59655, Lille1, France

ABSTRACT

The major episode of Corg-rich black shales known as the Bahloul Formation (latestCenomanian - earliest Turonian) and corresponding to the OAE-2 was studied for its calcareous and siliceous planktonic content, in two key localities, in order to clarify the biotic changes associated to this extreme paleoceanographic environment. The Bahloul coincides with a major turnover within the radiolarians and the extinction of the most specialized planktonic foraminifers, the keeled rotaliporids, whereas the opportunists  Heterohelix and  Guembelitria proliferate. These black shales show some common features : (1) the selected decrease in diversity within the radiolarians, whose assemblages in the lower to middle portion of the Bahloul comprise only Nassellaria, interpreted as possible deep dwelling taxa by analogy with the modern forms; (2) although planktonic foraminifers are the most susceptible to dissolution resulting in very scanty records, they also decrease in diversity associated with a relative increase in abundance of  Heterohelicacea and whiteinella. While the decrease in radiolarian diversity occurs within the siliceous black shale levels (Bargou area), (3) the changes, either as turnover or fluctuation in abundance of planktonic foraminifers and, to a minor extent, of radiolarian, occur in the simultaneously with the acme of Corg accumulation.

Depauperate radiolarian assemblages, characterized by the supposed deep-dwelling forms, occur generally in association with maximum organic carbon values (up to 7.5%) and d13Corg positive shif (-22.1‰). The changes of calcareous and siliceous plankton observed within the OAE-2 point to an increase in fertility of surface waters, possibly related to increased upwelling. The intensity of the perturbation during the Bahloul deposition, results in a major turnover in siliceous and calcareous plankton leading to anoxia at the sea- floor.

Structural context of the paleogeography of the Cenomanian-Turonian anoxic event in the eastern Atlas basins of the Maghreb

Mohamed Soua a,*, Oussema Echihi a, Missoum Herkat b, Dalila Zaghbib-Turki c, Jalel Smaoui a, Hela Fakhfakh-Ben Jemia a, Houda Belghaji a

SOUA et al 2009.pdf

a Entreprise tunisienne d’activités pétrolières, ETAP–CRDP, 4, rue des Entrepreneurs, La Charguia II 2035, Tunisia

bUniversité des sciences et de la technologie Houari-Boumediene, BP 32, El Alia, Bab Ezzouar, Alger, Algeria

c Département des sciences de la terre, faculté des sciences de Tunis, université Tunis El Manar, 1060 Tunis, Tunisia

 

Abstract

The regional Cenomanian-Turonian (C/T) structural framework of surface and subsurface coupled with subsidence data inferred from palegeographic and organic-rich C/T isopachus maps, generated in this work, from several basins, wells and outcrops of Tunisia and eastern Algeria were investigated and provide constraints on the structural and sedimentary evolution of this part of the southern Tethyan margin during the C/T times. This period is characterized by the development of extensional structures with tilted blocks and grabens, bounded listric normal faults. Subsidence during C/T time led to the accumulation of a thick sequence of laminated black shales and marls (up to 80 m thick in northwestern Tunisia and about 100 m thick in the Aures-Kef trough in northeastern Algeria). Sharp variations in thickness and facies towards the north and northeast indicate that basin subsidence was driven by regional tectonic movements along NW-SE, NE-SW and east-west trending normal faults issued from Tethyan rifting of the Upper Jurassic-Lower Cretaceous. The reduction of emerged areas since the Cenomanian inferred from the generated palaeogeographic map is demonstrated. The overall evolution is also maintened by halokinesis of Triassic salt creating subsident rim-synclines, where organic-rich facies prevail.

To cite this article: M. Soua et al., C. R. Geoscience xxx (2009). To cite this

article: M. Soua et al., C. R. Geoscience xxx (2009).# 2009 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Keywords:

Cenomanian-Turonian; Tunisia; Algeria; Paleogeography; Halokinesis; Horsts; Grabens

 

Windows !! solution to forgotten password

The tool we’ll be using here is Ophcrack. It is an open-source password finder. The technology it uses to break Windows passwords is called “rainbow tables” and was described by Philippe Oechslin in Making a Faster Cryptanalytic Time-Memory Trade-Off. A rough way to describe this technique is to say that tables of possible hashes are precomputed so that you can iteratively compare the windows hashes to precomputed bits and piece together the hash and its value more quickly than brute-force guessing.

 Please note that we try to find a solution to a forgotten password and this is not a piracy!! Federal law prohibits the possession of unauthorized access codes to computer systems. If you want to try cracking passwords, please obtain hashes from your own machine, or use the example hashes provided here.

 

1) Setting up shop

 The first thing you need is the software and rainbow table sets. You can download Ophcrack 2.2 from Sourceforge, and then browse to LASEC to download the SSTIC04-5k rainbow table. You’ll need a significant amount of memory to load this rainbow table. If you have less than 1 GB of RAM, try the smaller table.

 The installation of Ophcrack 2.2 should go smoothly. Make sure you choose to download the tables seperately:

 You’ll notice a lot of GTK* files being installed–that’s nothing to worry about. GTK is the Graphical Tool Kit, a way for linux programs to create graphical interfaces.

 

2) where’can we find  sam file

Now that you’ve got Ophcrack and rainbow tables installed, you’ll need hashes. There are three places to find them on Windows XP:

  In the folder C:windowssystem32config. This folder is locked to all accounts (including an Administrator account) while running, except the special System account.

In a SAM file from C:windowsrepair if rdisk has ever run 

In the registry, under HKEY_LOCAL_MACHINESAM, which is locked to all accounts

 This doesn’t look good for retreiving the windows hashes! Well, to work around the built-in windows protections, we can recover hashes by the following techniques:

 Boot to linux and copy the file directly from C:windowssystem32config. This is probably too troublesome for most users, but with a liveCD it’s trivial.

Run pwdump2, including in Ophcrack, to trick out the registry values. If you didn’t change any settings, it should be installed in C:Program Filesophcrackwin32_tools.

Naturally, I’ve censored the hashes and the number of users. If you’d like some hashes to play with, here are hashes for users with passwords varying from length from 1 to 7 characters long: test-hashes.txt.

 

3) Here we are, let’s go

Hashes in hand, start up Ophcrack:

 

Then click “load, PWDump file,” and select either the hashes you got from pwdump2, my sample hash file, or some other source of SAM hashes:

 

The last thing we need to do is load our rainbow tables. Click “Tables” and select the location and type of rainbow hash table you’re using, in our case the 5k tables: Now you can click the big “Launch” button and wait. It will first load the tables (0-3 in my case) into memory, a process that takes several minutes. When this is complete, it will begin trying passwords:

 The final screen gives a breakdown on how long it takes to actually find these passwords–some of which are quite hard:

تونس تمنح شركتين رخصة للتنقيب عن النفط

فى غضون عشرين يوم تونس تمنح شركتين رخصة للتنقيب عن النفطا 

  منحت الحكومة التونسية شركتين فرنسية وأسترالية رخصة جديدة للتنقيب عن النفط والغاز فى البلاد،هى الأولى خلال العام الجارى والثانية فى غضون 20 يوماوقال مصدر رسمى السبت إن الشركتين اللتين فازتا بهذه الرخصة هما مؤسسة "بريمول" التابعة للشركة الفرنسية "سوبروديس"،والمؤسسة الأسترالية "اويل زيرتش تونس المحدودة".

ووقّع على اتفاقية هذه الرخصة وزير الصناعة والطاقة التونسى عفيف شلبى الرئيس المدير العام لشركة "بريمول" جون بيار،ومانزونى ومدير تنمية الأعمال بمؤسسة "اويل سيرتيش تونس المحدودة" اندرو لوكان،إلى جانب المدير العام للشركة التونسية للأنشطة البترولية خالد بالشيخ.

وتحمل هذه الرخصة التى رصدت لها استثمارات فى حدود 5 ملايين دولار، إسم "الكاف"،وهى تغطى مساحة 2836 كيلومترا مربعا،وتمتد على محافظتين هما الكاف "171 كيلومترا غربى تونس العاصمة"،وجندوبة "254 كيلومترا شما غرب العاصمة تونس".وستقوم الشركتان الفرنسية والأسترالية بإعداد الدراسات الميدانية، والتنقيب عن المحروقات، لمدة أربع سنوات فى المنطقة المذكورة، إلى جانب حفر بئر استكشافية.
وتأمل السلطات التونسية من وراء هذه التراخيص، التى باتت تغطى أكثر من 70 % من إجمالى مساحة البلاد، تحقيق اكتشافات نفطية جديدة، لاسيما وأن ميزان الطاقة لديها يعانى عجزا متواصلا.