Source, facies, and sedimentary environments of the Middle to Upper Jurassic strata in the Kerman and Tabas areas, east-central Iran [Elektronische Ressource] / vorgelegt von Masoud Zamani Pedram

Masoud Ramani Pedram

Informations

• Publié par: julius-maximilians-universitat_wurzburg
• Publié le: 01 janvier 2011
• Nombre de lectures: 22
• Langue: English
• Poids de l'ouvrage: 110 Mo

Extrait

Source, facies, and sedimentary environments of the
Middle to Upper Jurassic strata in the Kerman and Tabas
areas, east-central Iran
Dissertation zur Erlangung des
Naturwissenschaftlichen Doktorgrades
der Bayerischen Julius-Maximilians-Universität Würzburg
Vorgelegt von
Masoud Zamani Pedram
aus
Tehran in Iran
Würzburg 2011Eingereicht am: …………………….
1. Gutachter: Prof. Dr. F. T. FÜ RSICH
2. Gutachter der Dissertation: M. WILMSEN
1. Prüfer: Prof. Dr. F. T. Fürsich…….………….…………………
2. Prüfer: Prof. Dr. H. De Wall ……..…………………………….
der mündlichen Prüfung
Tag der mündlichen Prüfung: …………………………………..
Doktorurkunde ausgehändigt am:………Contents
1 Introduction 1
2 Methods and material 3
3 Geological setting 5
4 Jurassic stratigraphy of the Tabas Block 7
5 Sections
5.1 Echellon section 10
5.2 Doshakh section 16
5.3 Kamar-e-Mehdi section 24
5.4 Qoleh Nar section 35
5.5 Abdoughi section 42
5.6 Ravar section 45
5.7 Bidou section 60
5.8 Bolboulieh and Mohamadshah sections 70
6 Lithostratigraphy
6.1 Hojedk Formation 92
6.2 Parvadeh Formation 93
6.3 Baghamshah Formation 95
6.4 Gypsum-Pecten Limestone (Kamar-e-Mehdi Formation) 97
6.5 Kamar-e-Mehdi Formation (Nar Limestone Member) 100
6.6 Magu Gypsum Formation 102
6.7 Bidou Formation 104
6.8. Lithostratigraphic correlation 109
7 Macrobenthic fauna
7.1 Parvadeh Formation 112
7.2 Baghamshah Formation 112
7.3 Kamar-e-Mehdi Formation 113
7.4 Bidou Formation 113
8 Ichnotaxonomy 124
9 Sedimentary petrography
9.1 Introduction 133
9.2. Description of grain types, calculated parameters and counted symbols 133
9.3 Siliciclastic rocks with gravel-sized clasts (conglomerate) 136
9.4 Siliciclastic rocks with sand-sized clasts 137
9.5 Siliciclastic rocks with silt- and clay-sized grains 140
9.6 Heavy minerals 141
10 Facies and sedimentary environments
10.1 Braided stream deposits (fluvial channel fill deposits) 148
10.2. Low sinuosity river deposits 149
10.3 Overbank and flood plain deposits 149
10.4. Levee deposits 150
10.5. Lower to upper delta front deposits 150
10.6. Bay/shallow lagoonal? siliciclastic deposits 151
10.7. Storm deposits 152
10.8. Beach deposits 158
10.9. Channel inlet deposits 158
10.10. High-energy shallow marine deposits 16010.11 Lower shoreface to offshore siliciclastic deposits 161
10.12 Low energy, intertidal to supratidal deposits (sabkha) 164
10.13. Low-energy restricted shallow lagoonal deposits 165
10.14. Deep subtidal/lagoonal deposits 168
10.15. Patch reefs 171
10.16. Carbonate platform margin deposits 171
11 Source rocks, palaeogeography and syn-tectonic events
11.1 Source rocks and tectonic context 173
11.2 Palaeogeography 188
12. Conclusions 196
13 Acknowledgments 200
14 References 201
LebenslaufChapter 1 Introduction
1 INTRODUCTION
Middle to Upper Jurassic rocks are widely distributed and superbly exposed on the
western Tabas Block of the central-east Iranian Microplate (CEIM). Based on AGHANABATI
(1977, 1998), the Upper Triassic-Jurassic succession can be subdivided into a numbers of
formations, which can be combined into two groups separated by unconformities related to
tectonic events. The Shemshak Group is intercalated between the Early and the Mid
Cimmerian tectonic event (see also FÜ RSICH et al. 2009) and the Magu Group is sandwiched
between the Mid to Late Cimmerian tectonic event. In the new lithostratigraphic scheme of
WILMSEN et al. (2003, 2009), the Magu Group in the northern part of the Tabas Block is
subdivided into three subgroups, i.e. the Baghamshah, Esfandiar and Garedu subgroups. In
the Zarand-Kerman area, the Magu Group laterally turns into the Bidou Formation. Earlier on,
HUBER & STÖ CKLIN (1954) had introduced the Bidou Series for the Middle-Upper Jurassic
rocks north of Kerman, close to the Hojedk Coal Mine. According to SEYED-EMAMI (1999),
the Bidou Series is composed of the Bidou Formation (Bathonian-Callovian), Pectinid
Limestone (Upper Callovian to Oxfordian and Kimmeridgian) and Ravar Formation
(Kimmeridgian and probably Tithonian). He suggested to use the Bidou Group just for the
non-separated Bidou Series. AGHANABATI (2004, 257) believed the Bidou Group ("Bidou
Series") to be equivalent of the Magu Group (see also WILMSEN et al. 2009). The aim of this
study is to analyse the facies and to reconstruct the palaeoenvironments of the Middle to
Upper Jurassic strata (Magu Group and Bidou Formation) of the western and southern Tabas
Block, combining sedimentary petrography, sedimentology, lithostratigraphy, trace fossils,
macrofossil and heavy mineral analysis in order to trace the evolution of the sedimentary
basin and to elucidate any synsedimentary tectonic events. This approach is used to test the
hypothesis that during the Jurassic, the Tabas Block was a tilted fault block, more or less in its
present position between the neighbouring Yazd and Lut blocks and adjacent to the
Neotethys. Previous studies of the Middle to Upper Jurassic strata were mainly concerned
with mapping (e.g., HUCKRIEDE et al. 1962; STÖ CKLIN et al. 1965; RUTTNER et al. 1968;
SAHANDI et al. 1990; HAJ MOLA ALI 1995; VAHDATI 1995; SHAIKHOLESLAMI, M.R. 1999;
KARIMI-BAVANDPUR et al. 2002; AZHDARI 2004). During last few years, some papers on the
lithostratigraphy attempted to improve and define more precisely a number of formations of the
Magu Group mainly on the northern Tabas Block (Qaleh Dokhtar Formation: SCHAIRER et al. 2000,
FÜ RSICH et al. 2003a; Kamar-e-Mehdi Formation: WILMSEN et al. 2003, 2009; Korond Formation:
1Chapter 1 Introduction
SCHAIRER et al. 2003; Sikhor Formation: FÜ RSICH et al. 2003b; general review of the Middle Jurassic
lithostratigraphy of Iran: SEYED-EMAMI et al. 2001; new evidence on the lithostratigraphy of the
Jurassic system on the northern Tabas Block: SEYED-EMAMI et al. 2005).
2Chapter 2 Methods & Material
2 METHODS AND MATERIAL
Nine sections of the Middle to Upper Jurassic strata were measured bed-by-bed in the
western and southern Tabas Block (Fig. 1) using a modified Jacob Staff (SDZUY &
MONNINGER, 1985). Over 400 outcrop samples were collected. Siliciclastic rocks were
studied by petrographically evaluating mineral composition, texture and diagenetic
characteristics (see Chapter 9). The textural maturity was determined by the grain shape
(TUCKER 1981), roundness of sediment grains (PETTIJOHN et al. 1987; TUCKER 1991), and the
degree of sorting (FOLK 1951; COMPTON 1962). Siliciclastic arenaceous rocks were classified
according to composition (PETTIJOHN et al. 1987). For determination of the grain-size, the
scheme of WENTWORTH (1922) was used. Several samples were collected to determine the
heavy mineral composition as index of the composition of rocks in the source area (BOSWELL
1933). Detrital heavy minerals were studied under a polarized (MANGE & MAURER 1992) and
binocular microscope (DEVISMES 1978). Several samples of fine-grained siliciclastic rocks
(marl, mudstones and shales) were taken in order to analyse the clay-mineral assemblages.
The study of clay-mineral assemblages was carried out by means of X-ray diffraction (XRD)
analysis. To characterize carbonate rocks based on their depositional, biogenic or diagenetic
texture, the classification schemes of DUNHAM (1962), EMBRY & KLOVAN (1972), and
Khosro-Tehrani (2007) were used. To describe skeletal and non-skeletal particles in thin-
sections, ADAMS et al. (1984), ADAMS & MACKENZIE (1998), and FLÜ GEL (2004) were used.
The benthic macrofauna was identified by HOLZAPFEL, 1998, FÜ RSICH (pers. comm. 2007).
Determination of trace fossils was based, for example, on FÜ RSICH (1974), HÄ NTZSCHEL
(1975), and FREY (1975). The rich literature on sedimentary structures (e.g. REINECK & SINGH
1973; POTTER & PETTIJOHN 1977; ALLEN 1984; STOW 2005) has been applied in the field.
3Chapter 2 Methods & Material
Fig. 2.1. Locality map of measured sections indicated by black squares and major structural units (blocks and
block-bounding faults) of east-central Iran.
4Chapter 3 Geological setting
3 GEOLOGICAL SETTING
The concept of a distinct fault-bounded Central-East Iranian Microcontinent, which
consists of three major crustal domains: the Lut Block, Tabas Block and the Yazd Block (e.g.,
ALAVI 1991; FÜ RSICH et al. 2009), was first introduced by TAKIN (1972; Fig. 2). These
blocks, now adjoined from east (Lut Block) to west (Yazd Block), are separated by a series of
intersecting regional-scale faults. Each block features a particular overall deformation style
and pattern of Recent seismicity, distinguishable from those in the adjacent domains
(BERBERIAN 1981). The overall uniformity of the Eocambrian (Late Neo-Proterozoic) and
Palaeozoic platform strata that covered the Zagros, Central Iran and the Main Alborz
provinces led to the predominant notion that all these regions were once part of the undivided
Palaeozoic Arabian-Iranian platform of Gondwanaland (STÖ CKLIN 1968, 1974). The Iran
Plate as a part of the Cimmerian continent collage collided with the Turan Plate during the
Late Triassic (Early Orogeny), either at the Ladinia