کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4690277 | 1636135 | 2009 | 14 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Sedimentology and allostratigraphy of post-240Â ka to pre-26.5Â ka lacustrine terraces at intracaldera Lake Rotorua, Taupo Volcanic Zone, New Zealand
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Sedimentology and allostratigraphy of post-240Â ka to pre-26.5Â ka lacustrine terraces at intracaldera Lake Rotorua, Taupo Volcanic Zone, New Zealand Sedimentology and allostratigraphy of post-240Â ka to pre-26.5Â ka lacustrine terraces at intracaldera Lake Rotorua, Taupo Volcanic Zone, New Zealand](/preview/png/4690277.png)
چکیده انگلیسی
Lake Rotorua partially occupies a nearly circular 20Â km diameter volcano-tectonic depression formed at c. 240Â ka by eruption of the voluminous Mamaku Ignimbrite. Three distinct lacustrine littoral terraces, defined on the basis of contrasting geomorphology and field relations, and separated by tephrostratigraphically dateable unconformities and basin-floor disconformities, fringe much of the lake basin. They are here correlated with former high-stands of the lake which resulted from the blockage and re-establishment of a number of alternative outlets due to tectonic activity and volcanism at both the host and adjacent volcanic centres. The unconformities allow division of the deposits into three allostratigraphic units, each of which is then characterised by elevation and sediment provenance. The <Â 240Â ka, post-Mamaku alloformation comprises the highest terrace (up to 415Â mASL), and represents the high-stand of an intracaldera lake accumulated in the newly created basin after the eruption of the Mamaku Ignimbrite. Considerable uncertainty surrounds the initial direction of overflow from this level, but the lake may have drained southwards for a period through the Hemo Gorge, through the Ngakuru Graben/Kapenga Caldera area and into the Waikato River catchment. The second alloformation, consisting of volcaniclastic sediments forming shoreline and littoral terraces at c. 380Â m elevation developed after the eruption of the 60Â ka Rotoiti/Earthquake Flat pyroclastic flows from the neighbouring Okataina Volcanic Centre blocked northern and southern routes out of the lake basin. A northeasterly outlet subsequently became established at a lower level through tectonic subsidence of the Tikitere Graben, creating a drainage path into the Haroharo caldera from where it flowed into the Bay of Plenty via the Kawerau Canyon. The post-36Â ka Hauparu alloformation forms the third shoreline terrace at elevations up to 349Â mASL. It is the product of a temporary high-stand from blockage of the Tikitere Graben drainage path by pyroclastic debris from the voluminous 36Â ka Hauparu eruption. Subsequently, episodic growth of the Haroharo resurgent dome complex between 25 and 9Â ka in the adjacent Okataina Volcanic Centre forced Lake Rotorua to rise above its post-Hauparu lowstand level to an elevation where it could overtop a drainage divide on the northern rim of Lake Rotoiti and gain access to the catchment of the Kaituna River, hence establishing the current outlet channel.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Sedimentary Geology - Volume 220, Issues 3â4, 15 October 2009, Pages 349-362
Journal: Sedimentary Geology - Volume 220, Issues 3â4, 15 October 2009, Pages 349-362
نویسندگان
R. Marx, J.D.L. White, V. Manville,