ORIGIN OF DIAPIRS/MUD VOLCANOES
http://www.gstt.org/teaching/origin.html
The term "mud-volcano" generally is applied to a more or less violent eruption or surfaces extrusion of watery mud or clay which almost invariably is accompanied by methane gas, and which commonly tends to build up a solid mud or clay deposit around its orifice which may have a conical or volcano-like shape.
The source of a mud volcano commonly may be traced to a substantial subsurface layer or diapir of highly plastic, and probably undercompacted, mud or shale.
Mud volcanoes also commonly appear to be related to lines of fracture, faulting, or sharp folding.
There appears to be a close interrelation between undercompacted (overpressured) muds or shale bodies, mud or shale diapirs, mud lumps, and mud volcanoes; and all degrees of gradation from one to another. Mud volcanoes are one of the most useful surface sources of information on the nature of materials in mud diapirs and undercompacted shale bodies.
The motivating force responsible for a mud volcano is, in part, simply the weight of rock overburden borne by the fluid content of undecompacted shales.
However, mud volcanoes all over the world are associated so invariably with quietly or explosively escaping methane gas that it is reasonable to conclude that the presence of methane gas in the subsurface is also an essential feature of the phenomenon.
The mud of the volcanoes is a mixture of clay and salt water which is kept in the state of a slurry by the boiling or churning activity of escaping methane gas.
Probably the methane gas was derived either directly from organic matter in muds or shales or from secondary accumulations in sand stringers within the source-rock shale or from larger reservoirs just above or just below such shales.
Some liquid oil often, but not always, is associated with the hydrocarbon gases of mud volcanoes.
Commonly the activity of a mud volcano is simply a mild surface upwelling of muddy and usually saline water accompanied by gas bubbles.
However, many ,instances are known of highly explosive eruptions where large masses of rock have been violently blown out hundreds of feet into the air and scattered widely over the countryside.
These intermittent violent eruptions strongly suggest that motive force is not merely weight of gradually increasing overburden but is due to periodic buildup and release of internal pressure from the generation of methane gas within the shale body or diapir.
diagrams taken from : Structural evolution of shale diapirs from reactive rise to mud volcanism: 3D seismic data from the Baram delta, offshore Brueni Darussalam. Van Rensbergen et al. Journal of the Geological Society of London, Vol. 156, 1999, pp 633-650.
Editorial
Mud volcanoes: generalities and proposed mechanisms
Marine and Petroleum Geology
Mazzini
Marine and Petroleum Geology 26 (2009) 1677-1680
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Mud volcanism: Processes and implications
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Editorial Mud volcanism: Processes and implications Mud volcanoes: generalities and proposed mechanisms Mud volcanoes can be large and long lived geological ...
seismo.berkeley.edu/~manga/mazzini2009.pdf
Mud volcanoes generalities and proposed mechanism
Mud volcanoes can be large and long lived geological structures that morphologically resemble magmatic volcanoes.
Because of their capricious behavior and their spectacular morphology and landscapes, mud volcanoes have attracted attention since antiquity.
More recently, mud volcanoes have become the focus of extensive studies for natural science research, including geologists and biologists.
Mud volcanoes can be essentially divided in two groups: those associated with magmatic complexes and those related to petroleum provinces.
Their occurrence is broadly distributed throughout the globe in both passive and predominantly active margins, often situated along faults, fault-related folds, and anticline axes.
These structures act as preferential pathways for deep fluids to gather and ultimately reach the surface. Mud volcanoes episodically experience violent eruptions of large amounts of gas mixed with water, oil, mud and rock fragments forming the so called ‘‘mud breccia’’.
The periodical eruptions can produce volcano-shaped mountains that can reach kilometres in size.
Detailed studies of mud volcanoes have been conducted for decades (e.g. Jakubov et al., 1971; Higgins and Saunders, 1974; Barber et al., 1986; Brown, 1990; Camerlenghi et al., 1992; Kholodov, 2002; Kopf, 2002).
Below I summarize the main findings so far, combined with my own suggested mechanisms (Fig. 1).
The main driving engine of the eruptions is overpressured methane rising from source rocks and hydrocarbon reservoirs at greater depths.
Other known overpressure buildup mechanisms that contribute to the brecciation of the deep sedimentary units include for example the dewatering of thick clay-rich sedimentary units, and geochemical reactions in sedimentary units with high temperature gradients. These fluids overpressured fluids gather along morphological discontinuities and favorable geological structures (e.g. fault planes, anticline axes, preexisting deformations).
During this overpressure buildup a dome or diapir-shaped feature of brecciated sedimentary units forms in the subsurface. The rise of the fluids and the growth if this diaper is partly self-sustained by buoyancy and by the constantly increasing volume of fluids at shallower depth.\ A suggested scenario summarizing the birth of a mud volcano and the eruption mechanisms envisages that when the subsurface overpressure reaches a threshold depth where the overburden weight is exceeded, fracturing and breaching of the uppermost units occur, sometimes facilitated by external factors (e.g. earthquakes).
Brecciated sediments throughout the feeder channel have a reduced cohesion. As breaching of the overburden occurs, the accumulated pressure drops and the lower cohesion media is easily fluidized and ultimately vacuumed to the surface.
This suggested mechanism does no imply significant movement of the brecciated sediments prior to the eruption neither during the growth of the emerging diapir.
An eruption where large rocks rise directly from the roots of the feeder channel all the way up to the surface, is unrealistic to happen. This is especially unlikely when considering basins like the Caspian where some mud volcanoes have root as deep as 15 km.
I suggest that the huge blocks observed at some mud volcano locations and proven to originate from several kilometres of depth, reach the surface after several eruptive cycles, each one contributing to the rise
of the oldest sediments. In this sense, I envisage that the youngest eruptions have a larger amount of old rocks.
The intimate association of petroleum reservoirs and mud volcanoes in sedimentary basins makes such structures interesting for hydrocarbon exploration. However mud volcanoes may also pose a geohazard for drilling and platform constructions due to the potentially violent release of large amounts of hydrocarbons and mud breccia.
Additionally, the eruption of greenhouse gases via mud volcanoes may influence global climate regimes and several attempts to estimate their contribution have been made.
Offshore mud volcanoes are frequently associated with the presence of gas hydrates. As these buried methane reserves are likely to be exploited in the future, mud volcanoes will undoubtedly remain a key part of the geological arena.
The special issue
The idea of a special issue on mud volcanism was suggested by Elsevier after the successful AGU session on ‘‘Mud volcanoes and their eruption dynamics’’ held in San Francisco in December 2007.
Marine and Petroleum Geology Journal was the best choice to gather contributions on mud volcanism investigated both onshore and offshore with constantly updated approaches.
Mud volcanoes represent a relatively young field of study especially when compared with the more popular magmatic volcanoes.
A special issue devoted entirely to mud volcano contexts, processes, and resultant landforms is both relevant and timely not only because the subject is gaining increased attraction within the scientific community but also because a cohesive presentation of the state of research is required to direct avenues of research.
There are several issues that still remain unresolved. For example what are the geochemical reactions that occur during the rise of fluids at dormant stage? Is it possible to predict mud volcano eruptions? What are the possible triggers for the eruptions?
Is there any rise of the brecciated sediments along the conduit prior to an eruption? From what depth are the solids being erupted during a single event? What do the seeping fluids tell us?
This special issue aims to provide an overview of the different settings and disciplines to investigate mud volcanoes and their processes, and to present the state-of-the-art in the most recent ongoing research.
The themes described in this issue (Fig. 2) are divided in five main sections: 1) Onshore mud volcanism, 2) Lusi mud volcano, 3) Offshore mud volcanism, 4) Extraterrestrial mud volcanism, 5) Modelling mud volcano eruptions.
Essentially all offshore and onshore mud volcanoes are studied during their dormant period (intervals between eruptions that are characterized by no seepage, or micro seepage or focused seepage of fluids and sediments). Onshore mud volcano provinces are located throughout the globe mainly in collisional settings. Sampling onshore is facilitated and petrography and geochemical analyses of the seeping sediments and fluids represent the most traditional approach to explore the geometry of
the subsurface plumbing system and the origin of the fluids during the quiescent periods. Using this type of approach, Etiope et al. (2009) and Mazzini et al. (2009) tried to estimate the main geochemical processes ongoing in the feeder channel and in the near subsurface during the dormant activity. New analytical and monitoring approaches (e.g., cyclicity of the eruptions, temperature logging, and penetrometry tests) are also described aiming to understand the mechanisms ongoing during the slow seepage of fluids and to predict the charging of the mud volcano system prior to new eruptions (Deville and Guerlais, 2009; Kopf et al., 2009).
Studies of erupting mud volcanoes are exceptional.
The 29th of May 2006 eruption of the Lusi mud volcano (Indonesia) provided a unique opportunity to experiment with multidisciplinary studies an erupting mud volcano from its birth. This seemingly unstoppable eruption (to date, June 2009) is an ideal event to constrain the mechanisms driving mud volcano eruptions and their association and similarities with magmatic volcanoes. Moreover, the artificial dams built around the crater provide an exceptional setting that allows sampling of fluids from the crater during the eruption.
Lusi represent a real natural laboratory to explore the origin of fluids during eruption events (as opposite to common studies) and to distinguish between the possible triggers and, most importantly, the causes that lead to an eruption. Novel multidisciplinary studies that are described herein include a review of triggering mechanisms complemented with GPS monitoring, SAR interferometry, mathematical and analogue simulations. These are used to
monitor and to understand the Lusi event as well as provide possible alternatives to explain the trigger of Lusi and other mud volcanoes (Fukushima et al., 2009; Istadi et al., 2009; Manga et al., 2009; Mazzini et al., 2009; Sawolo et al., 2009).
Numerous studies of offshore mud volcanoes have been completed during the last decades. This issue describes acoustic, video and sampling techniques from recently discovered mud volcano provinces in the Mediterranean Sea, Gulf of Mexico and Black Sea.
Deep seismic and sides can sonar approaches are used to define the morphology, the history of the activity of volcanoes as well as the internal structure of the feeder channel (Praeg et al., 2009; Savini et al., 2009).
Detailed studies on the near subsurface, including fluid flow rates, thermal anomalies and video-sampling observations, describe the possible link between gas hydrates stability and the eruption dynamics, and give important estimate about the transport of methane to the atmosphere (Feseker et al., 2009; MacDonald and Peccini, 2009; Sahling et al., 2009).
The phenomenon of mud volcanism has been recently suggested for other planets in the solar system and in particular for Mars.
Here, we describe recent studies that review the possible regions where Martian sedimentary basins might fulfil the requirements for mud volcanism and where satellite surveys reveal images similar to those observed in mud volcano provinces on Earth (Skinner and Mazzini, 2009).
Despite the numerous studies, the mechanisms controlling mud volcano eruptions are still debated.
Among the most advanced and innovative approaches are the numerical modeling simulations.
In this special issue are included some examples of revolutionary techniques that help to test hypotheses from the bosom of the Earth exploring the cyclicity and the parameters controlling the blasts (Gisler, 2009; Zoporowski and Miller, 2009).
Fig. 2. Some spectacular examples of onshore, offshore and extraterrestrial mud volcanoes. (A) Tuorogai Mud volcano (Azerbaijan) is considered to be one of the biggest onshore mud volcanoes, with estimated 343 millions cubic meters of mud breccia reaching a size between 2900 and 3200 m and a height of 500 m (Jakubov et al., 1971). (B) Steam-dominated eruption of the Lusi mud volcano where mud was ejected in the air for several tens of meters. Note the trees in the background. Since May 2006 the Lusi mud volcano is erupting mud that is now covering a surface of nearly 7 km2. The flooded area would certainly be much wider without the containment dams that are constantly build around to protect the surrounding villages. Image courtesy of the Lusi Media Center. (C) Inferred mud volcano features on the Martian surface, located in the Galaxias Fossae region.
Note the moat surrounding the conical shape similar to collapse features observed on Earth and the flow towards the south east. Excerpt of THEMIS V19054019, centered at 141.0E, 38.9N,19 m/px. (D) High-resolution 3D seismic data show the internal structure of the Mercator mud volcano and a buried diapir in the Gulf of Cadiz (after Berndt et al., 2007). Horizontal scale ca. 6 km. (E) Historic seismic profile of MSU mud volcano, Black Sea (Ivanov et al., 1992).
JOINT CONVENTION BALI 2007
The 36th IAGI, The 32nd HAGI, and the 29th IATMI
Annual Convention and Exhibition
Bali, 13-16 November 2007
Awang Harun Satyana (BPMIGAS)
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ABSTRACT
Jenggala and Majapahit are two empires of 11th to early 16th centuries located at the Brantas delta, East Java, Indonesia. The growth, rise, and fall of these two empires are more or less related to geological processes undergone by the Brantas delta. The Jenggala empire lasted for only 50 years, fell in 1116 AD, and annexed by the Kediri empire. The Majapahit empire started in 1293 AD, rose successfully during almost the first hundred years, declined, and fell in 1478 AD, became the subordinate to the Demak empire, and ended in 1518 AD.
Based on interpretations of the historical chronicles of the Kitab Pararaton, Serat Kanda, and Babad Tanah Jawi, folklore developing in the Jenggala and Kediri period, geological setting of the area where Jenggala and Majapahit existed, and making an analogue to the present LUSI (Sidoarjo mud) mud volcano eruption which occurred close to the area where the center of the Jenggala empire was; there is a possibility that natural disasters of mud volcanoes eruptions had declined both Jenggala and Majapahit empires before they were annexed by the competing empires.
The hypothesis that the decline of the Jenggala and Majapahit empires was caused by natural disaster is based on and examined by five theses as follows. (1) Thesis of disasters called ”banyu pindah” 1334 AD and ”pagunung anyar” 1374 AD written in the Kitab Pararaton; (2) Thesis of chronowords (“suryasengkala”) explaining the fall of the Majapahit empire : ”sirna ilang krtaning bhumi” meaning 1400 Caka/1478 AD written in the Serat Kanda and Babad Tanah Jawi, which textually and grammatically can be re-defined as “loss by an earthy work” indicating a geological disaster; (3) Thesis of an event called the ”Guntur pawatugunung” in 1403 Caka/1481 AD which has mostly been interpreted as volcanic eruption (could also be mud volcano eruption) and is considerd as related to the “sirna ilang krtaning bhumi” because of their contemporaneity. (4) Thesis of folklore called ”Timun Mas” which developed in the Jenggala/Kediri period; this story perfectly represents the sequences of mud vocano eruption. The story was possibly composed to explain this eruption; (5) Thesis of the geological setting of the areas where Jenggala and Majapahit empires were located; the two empires were located at the eastern part of the Kendeng depression partly covered by the Brantas delta; the Kendeng depression is an elisional basin, a condition required for the occurrence of mud volcano eruption.
The Kendeng depression is an ideal elisonal system characterized by thick young clayey and sandy sediments rapidly deposited into the subsiding basin, not perfectly compacted, mobile, overpressured, intensive smectite to illite transformation; high geothermal gradient due to the southern border of volcanic arc; and strongly compressed forming anticlinorium. A number of mud volcanoes found along the Kendeng depression from Purwodadi to the Madura straits (such as bledug Kuwu, bledug Kesongo, Gunung Anyar, Kalang Anyar, Pulungan, LUSI) prove the effectivity of elisional system of the Kendeng trough which has been active sincethe Plio-Pleistocene.
Based on the geological principle of uniformity (the present is the key to the past) and that LUSI, Jenggala and Majapahit share a same place, it is considered that what is occurring presently on LUSI eruption could also happen during the Jenggala and Majapahit periods as natural disasters which significantly declined the two empires. This consideration is supported by historical chronicles, folklore, and geological analysis. A collaboration of historians, archaeologists, and geologists are required for confirming the hypothesis. The historical chronicles should be deliberately examined to check the treatises on disasters, the archaeological sites of Majapahit and Jenggala should be re-visited, and the areas of expected mud volcanoes during the Majapahit and Jenggala periods indicated in this study should be geologically investigated.
Kerajaan Jenggala dan Kerajaan Majapahit berpusat di delta Brantas, Jawa Timur pada sekitar abad ke-11 sampai awal abad ke-16. Perkembangan, kemajuan, dan keruntuhan kedua kerajaan ini sedikit banyak berkaitan dengan proses-proses geologi yang terjadi pada delta Brantas. Kerajaan Jenggala hanya bertahan sekitar 50 tahun, runtuh pada tahun 1116 M, dan sejak itu wilayahnya menjadi bagian Kerajaan Kediri.
Kerajaan Majapahit berawal pada 1293 M, maju dalam hampir seratus tahun pertama, mundur, runtuh pada 1478 M, menjadi bawahan Kerajaan Demak, dan berakhir pada 1518 M.
Berdasarkan penafsiran beberapa sumber sejarah (Kitab Pararaton, Serat Kanda, Babad Tanah Jawi), cerita rakyat, kondisi geologi wilayah Jenggala dan Majapahit, dan analogi terhadap semburan lumpur panas di Sidoarjo (LUSI) yang berlokasi di dekat pusat kerajaan Jenggala, terbuka kemungkinan bahwa kedua kerajaan tersebut telah mengalami kemunduran yang berarti akibat bencana alam berupa erupsi gunung-gununglumpur sebelum dianeksasi oleh kerajaan-kerajaan pesaingnya.
Hipotesis bencana erupsi gununglumpur pada masa Jenggala dan Majapahit didasarkan dan diteliti melalui lima tesis : (1) tesis bencana ”banyu pindah” 1334 M dan bencana ”pagunung anyar” 1374 M yang tercatat pada Kitab Pararaton; (2) tesis suryasengkala peristiwa keruntuhan Majapahit ”sirna ilang krtaning bhumi” yang berarti tahun1400 Saka/1478 M, tercatat dalam Serat Kanda dan Babad Tanah Jawi, dan secara leksikal dan gramatikal dapat didefinisikan ulang sebagai ”musnah hilang sudah selesai pekerjaan bumi” (berkonotasi kemusnahan akibat bencana kebumian/geologi); (3) tesis peristiwa ”guntur pawatugunung” pada tahun1403 Saka/1481 M yang telah banyak ditafsirkan para ahli sebagai bencana letusan gunungapi (atau dalam hal ini gununglumpur) yang berkaitan dengan ”sirna ilang krtaning bhumi” berdasarkan saat kejadian yang berdekatan atau sebenarnya bersamaan; (4) tesis folklor ”Timun Mas” yang berkembang pada masa Jenggala dan Kediri yang isi ceritanya sangat mirip dengan peristiwa kejadian erupsi gununglumpur, sehingga cerita rakyat ini bernilai dichtung und wahrheit (antara cerita dan kenyataan) untuk menggambarkan proses kejadian alam; dan (5) tesis geologi wilayah Jenggala dan Majapahit yang menunjukkanbahwa kedua kerajaan ini berlokasi di depresi Kendeng bagian timur yang di atasnya
sebagian ditutupi oleh delta Brantas dan bersifat elisional. Suatu sistem elisional akan mendorong terjadinya gejala diapir dan erupsi gununglumpur.
Depresi Kendeng tempat Jenggala dan Majapahit berlokasi merupakan sistem elisional yang ideal yang dicirikan oleh : sedimen lempungan dengan sisipan pasiran sangat tebal yang diendapakan dalam waktu singkat, sehingga tidak terkompaksi sempurna, labil, overpressured, transformasi mineral lempung smektit ke ilit yang intensif; mempunyai gradien geotermal yang tinggi akibat berbatasan dengan jalur gunungapi di sebelah selatan; dan terkompresi kuat sehingga membentuk jalur antiklinorium. Sejumlah gununglumpur yang ditemukan di sepanjang depresi Kendeng dari Purwodadi sampai Selat Madura, di bekas wilayah Majapahit dan Jenggala (misalnya : bledug Kuwu, bledug Kesongo, Gunung Anyar, Kalang Anyar, Pulungan, LUSI) membuktikan efektivitas sistem elisional depresi Kendeng yang telah aktif sejak Plio-Pleistosen.
Berdasarkan asas uniformisme (masa kini adalah kunci ke masa lalu - the present is the key to the past) dan bahwa wilayah Majapahit, Jenggala, dan LUSI berlokasi di wilayah yang sama; maka apa yang sekarang tengah terjadi dengan LUSI, dapat terjadi juga pada masa Jenggala dan Majapahit sebagai bencana yang cukup berarti untuk kemunduran kedua kerajaan tersebut. Data sumber sejarah, cerita rakyat, dan analisis geologi mendukung hal ini.
Diperlukan kerja sama antara ahli sejarah, arkeologi, dan geologi untuk meneliti ulang naskah-naskah lama sumber sejarah, mempelajari kembali situs-situs purbakala Majapahit dan Jenggala, dan melakukan penyelidikan geologi lapangan untuk memeriksa kemungkinan keberadaan endapan gununglumpur di daerah-daerah yang telah diidentifikasi dalam studi ini.