Sedimentologi & Stratigrafi - Klasifikasi Batuan Sedimen 2021 PDF

05/02/2021 PRODI TEKNIK GEOLOGI FAKULTAS ILMU DAN TEKNOLOGI KEBUMIAN (FITB) INSTITUT TEKNOLOGI BANDUNG (ITB) GL-3053 SEDIMENTOLOGI & STRATIGRAFI KLASIFIKASI BATUAN SEDIMEN 2 (Sedimentary Rocks Classification)...

05/02/2021 PRODI TEKNIK GEOLOGI FAKULTAS ILMU DAN TEKNOLOGI KEBUMIAN (FITB) INSTITUT TEKNOLOGI BANDUNG (ITB) GL-3053 SEDIMENTOLOGI & STRATIGRAFI KLASIFIKASI BATUAN SEDIMEN 2 (Sedimentary Rocks Classification) Dwiharso Nugroho [email protected] ; [email protected] 1 GL-3053 SEDIMENTOLOGI & STRATIGRAFI COURSE CONTENTS/ ISI KULIAH : o INTRODUCTION o SEDIMENTARY ROCKS CLASSIFICATION o TEXTURES OF SEDIMENTARY ROCKS o SEDIMENTARY PROCESSES (CLASTIC ROCKS) BOTTOM TRACTION AND SUSPENSION (GRAVITY) MASS FLOW o DEPOSITIONAL ENVIRONMENT (SILICICLASTIC ROCKS) o CARBONATE ROCKS (SYSTEM, PROCESSES AND EOD) o FACIES, FACIES ASSOCIATION AND CYCLICITY OF SEDIMENTARY ROCKS o CONCEPTS ON STRATIGRAPHY o STRATIGRAPHIC UNIT Photo courtesy of d|nug o STRATIGRAPHIC CORRELATION 2 1  05/02/2021 SEDIMENTARY ROCK CLASSIFICATION o GENETIC CLASSIFICATION: 1. Terrigenous Clastic sediments : sediment transported as solid particles 2. Chemical sediments: sediment that was once in solution 3. Biogenic, Biochemical, and Organic sediments : … 4. Volcaniclastic sediments : … Problems (with this classification) : We Do have Carbonate Clastics rocks. Carbonate Clastics are differ from Terrigenous Clastic in their composition (It’s similar in process) 3 SEDIMENTARY ROCK CLASSIFICATION o MIXED (DESCRIPTIVE AND GENETIC]) CLASSIFICATION: 4 2  05/02/2021 SEDIMENTARY ROCK CLASSIFICATION (GENETIC CLASSIFICATION) 1. Terrigenous clastic sedimentary rocks Sediments are generally loose material while sedimentary rocks are lithified sediment The chief constituents of detrital /terrigenous clastic rocks are grains or aggregates include: Lithic (rocks) fragments Quartz, Feldspars, Micas, and/or other minerals fragments Clay minerals Biogenic particles Authigenic minerals Grain size is used to distinguish among the various types of detrital rocks 5 1. Terrigenous clastic sedimentary rocks Basic of Detrital / Terrigenous clastic Rocks Classification A division on the basis of grain size is used as the starting point to classify and name terrigenous clastic sediments and sedimentary rocks There are a number of ways of providing subdivisions within these categories, but sedimentologists generally use the Wentworth Scale The phi scale is a numerical representation of the Wentworth Scale. The Greek letter ‘f’ (phi) is often used as the unit for this scale. Using the logarithm base two, the grain size can be denoted on the phi scale as :  = -log2 (grain diameter in mm) The negative is used because it is conventional to represent grain sizes on a graph as decreasing from left to right 6 3  05/02/2021 1. Terrigenous clastic sedimentary rocks Breccia & Conglomerate Breksi & Konglomerat 7 1. Terrigenous clastic sedimentary rocks Breccia & Conglomerate 8 4  05/02/2021 1. Terrigenous clastic sedimentary rocks Breccia & Conglomerate 9 1. Terrigenous clastic sedimentary rocks Breccia & Conglomerate 10 5  05/02/2021 1. Terrigenous clastic sedimentary rocks Breccia & Conglomerate 11 1. Terrigenous clastic sedimentary rocks Sandstone Batupasir 12 6  05/02/2021 1. Terrigenous clastic sedimentary rocks Sandstone Photo courtesy of d|nug 13 1. Terrigenous clastic sedimentary rocks Sandstone Photo courtesy of d|nug 14 7  05/02/2021 1. Terrigenous clastic sedimentary rocks Sandstone 15 1. Terrigenous clastic sedimentary rocks Basic of Sandstone classification 16 8  05/02/2021 1. Terrigenous clastic sedimentary rocks Mudrocks : Siltstone & Claystone 17 1. Terrigenous clastic sedimentary rocks Mudrocks : Siltstone & Claystone The general term mudrock is applied to any detrital sediment composed by silt and/or clay. If most of the particles (over 2/3) are clay-sized the rock may then be called claystone and if silt is the dominant size, a siltstone. Mixtures of more than one-third of each component are referred to as mudstone (Folk, 1974; Blatt et al., 1980). Silt is defined as the grain size of material that is 4 - 62 microns in diameter. The coarser grains of silt are just visible (naked eye or with a hand lens). Finer silt is commonly distinguished from clay by touch, as it feels ‘gritty’ while clay feels smooth. Clay is a textural term to define the finest grade of clastic sedimentary particles, those : less than 4 microns (Nichols, 2009), or 2 microns (Hopkins,1899; Burgess, 2006), or 1 microns (Atterberg,1903; Simonson,1999) in diameter. Individual particles are not visible to the naked eye and can only be decided with a high power optical microscope. Clay minerals are a group of phyllosilicate minerals that are the main constituents of clay-sized particles. 18 9  05/02/2021 1. Terrigenous clastic sedimentary rocks Mudrocks : Siltstone & Claystone 19 1. Terrigenous clastic sedimentary rocks Mudrocks : Siltstone & Claystone Photo courtesy of d|nug 20 10  05/02/2021 1. Terrigenous clastic sedimentary rocks Basic of Claystone Classification Clay minerals commonly form as breakdown products of feldspars and other silicate minerals. They are phyllosilicates with a layered crystal structure similar to that of micas and compositionally they are aluminosilicates. The crystal layers are made up of silica with aluminium and magnesium ions, with oxygen atoms linking the sheets 21 1. Terrigenous clastic sedimentary rocks Basic of Claystone Classification 22 11  05/02/2021 1. Terrigenous clastic sedimentary rocks Basic of Claystone Classification There are, at least, two principal techniques to distinguish and observe clay minerals (Tucker 1988): Scanning Electron Microscopy (SEM) is generated from secondary electrons produced by a fine electron beam that scans the surface of the sample. It produces microns across image with much higher resolution than image under an optical microscope X-ray diffraction pattern analysis An X-ray diffractometer (XRD) operates by firing a beam of X-rays at a powder of a mineral or disaggregated clay and determining the angles at which the radiation is diffracted by the crystal lattice. The pattern of intensity of diffracted X-rays at different angles is characteristic of particular minerals and can be used to identify the mineral(s) present. 23 1. Terrigenous clastic sedimentary rocks Basic of Claystone Classification Scanning Electron Microscopy (SEM) 24 12  05/02/2021 1. Terrigenous clastic sedimentary rocks Basic of Claystone Classification X-ray diffraction (XRD) pattern analysis 25 1. Terrigenous clastic sedimentary rocks PROPERTIES OF SOME CLAY MINERALS 26 13  05/02/2021 1. Terrigenous clastic sedimentary rocks Mudrocks (Siltstone & Claystone) → Shale The general term mudrock is applied to any detrital sediment composed by silt and/or clay. If most of the particles (over 2/3) are clay-sized the rock may then be called claystone and if silt is the dominant size, a siltstone. Mixtures of more than one-third of each component are referred to as mudstone (Folk, 1974; Blatt et al., 1980). The term shale is applied to any mudrock (e.g. by drilling engineers) but it is best to use this term only for mudrocks that show a fissility, that tends to break parallel to the bedding plane. (Note: the distinction between shale and slate, which is a term used for fine-grained metamorphic rocks which have cleavage planes.) Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility 27 1. Terrigenous clastic sedimentary rocks CLAY MINERALS SMECTITE ILLITE 28 14  05/02/2021 1. Terrigenous clastic sedimentary rocks Mudrocks (Siltstone & Claystone) → Shale VSH CALCULATION(SINGLE CLAY INDICATOR) a. Log Gamma Ray (GR) IGR= (GR – GRmin)/(GRmax – GRmin) GR = bacaan log GR pada zona interest GR min = bacaan log GR pada zona 100% bersih lempung GR max = bacaan log GR pada zona 100% lempung b. Log Spontaneous Potential (SP) Vsh = (SSP – PSP) / SSP = 1 – (PSP/SSP) SP = bacaan log SP pada zona interest SSP = static spontaneous potential of a thick clean sand or carbonate = the deflection from the shale/base line to the clean line PSP = pseudo static spontaneous potential (SP of shaly formation) = the deflection from the shale/base line to the curve reading 30 31 15  05/02/2021 SEDIMENTARY ROCK CLASSIFICATION (GENETIC CLASSIFICATION) 2. Chemical sedimentary rocks Inorganic processes Consist of precipitated material that was once Chert in solution Made of microcrystalline quartz Precipitation of material occurs in two ways Varieties include flint and jasper (banded form is Inorganic processes called agate) Organic processes (biochemical Evaporites : rock salt, gypsum origin) Evaporation triggers deposition of chemical precipitates Limestone : travertine, oolitic limestone Organic Process Limestone Most abundant chemical rock Composed chiefly of the mineral calcite Marine biochemical limestones form as coral reefs, coquina (broken shells), and chalk (microscopic organisms) Chert 34 2. Chemical sedimentary rocks Some of chert is thought to have a biological origin. It comes from skeletons of diatoms and radiolarians live in the sea water. These organisms have a glassy silica skeleton. Some sponges also produce "spicules" that are composed of silica. When these organisms die, their silica skeletons fall to the bottom and/or dissolve & recrystallize, and might become part of a chert nodule. In some areas the sedimentation rate of these materials is high enough to produce rock layers that are thick and laterally extensive. Chert formed in this way could be considered a biological origin sedimentary rock Photo courtesy of d|nug Photo courtesy of d|nug 35 16  05/02/2021 SEDIMENTARY ROCK CLASSIFICATION (GENETIC CLASSIFICATION) 3. Biogenic sedimentary rocks Biogenic sedimentary rocks are primarily composed of plant and animal remains, and include minerals created by organisms, such as corals, molluscs, diatoms or radiolarian Limestones, cherts, and coal 36 SEDIMENTARY ROCK CLASSIFICATION (GENETIC CLASSIFICATION) 4. Volcaniclastic sediments the products of volcanic eruptions or the result of the breakdown of volcanic rocks. 37 17  05/02/2021 The term "volcaniclastic" is The four main genetic categories of volcaniclastic deposits are: descriptive and applies to 1. autoclastic, - primary volcaniclastic deposits made of deposits composed particles (autoclasts) generated by in situ, non-explosive predominantly of volcanic fragmentation of lava or magma (autobrecciation and particles (Fisher, 1961). quench fragmentation Studies of volcaniclastic deposits, 2. pyroclastic, - primary volcaniclastic deposits made of therefore, require information on: particles (pyroclasts) generated by explosive eruptions 1. the clast-forming and deposited by primary volcanic processes (fallout, processes; flow, surge) 2. the clast transport and 3. resedimented syn-eruptive volcaniclastic, - volcaniclastic depositional processes; deposits from rapid resedimentation of texturally 3. post-emplacement syn- unmodified, freshly erupted pyroclastic or autoclastic volcanic processes particles; (welding, high- 4. volcanogenic sedimentary, - volcaniclastic aggregates temperature containing particles derived by erosion of preexisting devitrification, volcanic deposits and that were subject to significant hydration,vapour-phase reworking prior to final deposition, and/or that were crystallization, diagenetic redeposited long after eruption. (McPhie et. al., 1993) andhydrothermal alteration). (McPhie et. al., 1993) Nichols (2009): autoclastic, pyroclastic, and epiclastic 38 SEDIMENTARY ROCK CLASSIFICATION Carbonate Rocks ? Carbonate rocks are those in which the matrix and framework are composed of greater than 50% carbonate minerals (this definition excludes cement). Carbonate : Biogenic sediments (skeletals origin) Clastic sediments (skeletal and/or non skeletal clasts origin) Chemical sediments ( ) "Carbonate sediments are born, not made.“ (James, 1984) why ? The source for carbonate sediments is almost exclusively biological (Tucker & Wright, 1990) 39 18  05/02/2021 H+ + HCO4- + Ca2+ CaCO3 + H2O + CO2 40 The Carbonate Factory The carbonate factory is defined as the shallow illuminated seafloor, where sediment particles are ‘born’ through crystalization of skeletons or precipitation out of sea water. The carbonate factory is the core of carbonate deposition throughout the world. The carbonate factory is governed by the Goldilocks theory, where the environmental conditions have to be just right. The water can’t be to warm nor to cold to deep nor to shallow, salinitiy is also a key along with the amount of terriginous clastic sediment. 41 19  05/02/2021 Basic Carbonate Facies Autotroph: An organism capable of synthesizing its own food from inorganic substances, using light or chemical energy. Green plants, algae, and certain bacteria are autotrophs. An organism that is unable to synthesize its own organic carbon-based compounds from inorganic sources, hence, feeds on organic matter produced by, or available in, other organisms. 42 43 20  05/02/2021 Limestone components Grains mud pores cements 44 Non-Skeletal Grains Skeletal Grains peloids Sponges ooids Foraminifera Echinoderms pisolites Molluscs composite grains Bryozoans intraclasts Brachiopods oncoids Trilobites lithoclasts Ostracodes Stromatoporoids micritized grains Corals 45 21  05/02/2021 Dunham Classification of Carbonate Sedimentary Rocks The three criteria used to define the original Dunham classification: supporting fabric of the original sediment presence or absence of mud (micrite; the fraction