Sources and dispersal patterns of clay minerals in surface sediments from the continental-shelf areas off Alaska
Sources and dispersal patterns of clay minerals in surface sediments from the continental-shelf areas off Alaska
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DOI：
10.1130/0016-7606(1983)94
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发表时间：
1983-07
影响因子：
4.9
通讯作者：
A. Naidu;T. C. Mowatt
中科院分区：
文献类型：
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作者：
A. Naidu;T. C. Mowatt
阿拉斯加湾的三个矿物组被确认。峡湾和东部大陆架的冰海沉积物通常由原生层状硅酸盐、云母和绿泥石组成，在温和的化学风化条件下，这些矿物局部来源于泥质岩、杂砂岩和变质火山岩。在海湾北部，更多的乙二醇可膨胀粘土矿物（GECM）证实了该地区的粘土供应主要来自Yakataga和Poul Creek地层，在较小程度上来自Copper River。北方海湾粘土矿物组被阿拉斯加沿岸流输送到威廉王子湾中部和科迪亚克大陆架东北部。在墨西哥湾西部，毗邻阿拉斯加半岛的粘土矿物主要来自于通过库克湾流入的苏西特纳河，而外大陆架的粘土矿物可能来自于科迪亚克岛和卡特迈火山灰海底存款。在白令海东南部，GECM从65%到11%向西北方向逐渐减少，这是由于阿拉斯加半岛和阿留申群岛的沉积物输出逐渐减少，Kuskokwin河的伊利石可能略有增加。育空地区河是白令海北部的主要粘土来源，这一点可以通过GECM（20%-35%）和高岭石/高岭土比值的突然增加来表示。粘土矿物学表明，楚科奇海中部是育空地区粘土的主要储存库，这表明粘土矿物地层学研究的第四纪古地理的解释“白令吉亚”的影响。在博福特海近岸，不同的河流输入和它们的扩散电流的影响是明确的。外大陆架粘土矿物的分布缺乏明确的模式，可能是由于冰筏漂流和/或冰凿海底造成的沉积物的再加工和再分布造成粘土的偶然迁移。在博福特海内陆架的阿拉斯加部分，沉积物明显向西移动。在科尔维尔三角洲的伊利石/GECM比例明显向海增加暂时归因于再生的退化伊利石云母K +固定在盐水沃茨。在博福特大陆架中部，一个富含可膨胀粘土矿物的孤立沉积区可能是残留物。
The Three mineral suites were recognized in the Gulf of Alaska. The glaciomarine sediments of fjords and the eastern shelf consist typically of the primary phyllosilicates, micas, and chlorites, derived locally from argillite, graywacke, and metavolcanics under conditions of mild chemical weathering. More glycol-expandable clay minerals (GECM) in the north Gulf substantiate clay supply to that region primarily from the Yakataga and Poul Creek Formations, and to a lesser extent from the Copper River. The northern Gulf clay-mineral suite is transported to central Prince William Sound and northeast Kodiak Shelf by the Alaska coastal current. In the western Gulf, clay minerals adjacent to the Alaska Peninsula are derived principally from the Susitna River via Cook Inlet, whereas those of the outer shelf presumably have their provenance in Kodiak Island and the Katmai Ash submarine deposit. In the southeast Bering Sea, a progressive northwestward decrease in GECM, from 65% to 11%, is caused by a gradually decreased sediment export from the Alaska Peninsula and the Aleutians, with a possible minor increase in illite from the Kuskokwin River. The Yukon River is the predominant clay source for the north Bering Sea, as signified by an abrupt increase in that area of GECM (20% to 35%) and of kaolinite/chlorite ratios. Clay mineralogy indicates that the central Chukchi Sea is the major repository of the Yukon clays, suggesting that clay-mineral stratigraphic studies have implications for interpretation of the Quaternary paleogeography of “Beringia.” In the Beaufort Sea nearshore, influence of different fluvial inputs and their dispersals by currents are sharply defined. The lack of a definite pattern to the distribution of clay minerals in the outer continental shelf may be due to haphazard transport of clays by ice rafting and/or reworking and redistribution of sediments resulting from ice gouging of the sea substrate. Movement of sediment to the west in the Alaskan portion of the inner shelf of Beaufort Sea is evident. An apparent seaward increase in illite/GECM ratio in the Colville Delta is tentatively ascribed to regeneration of degraded illite-micas by K + fixation in saline waters. An isolated area of sediment rich in expandable clay minerals in the central Beaufort Shelf presumably is relict.